CN114556922A

CN114556922A - Method, apparatus and recording medium for encoding/decoding image by using partition

Info

Publication number: CN114556922A
Application number: CN202080071923.XA
Authority: CN
Inventors: 姜晶媛; 李河贤; 林成昶; 李镇浩; 金晖容; 朴光勋; 金太现; 李大永; 权佑原; 李元俊
Original assignee: Electronics and Telecommunications Research Institute ETRI; Kyung Hee University
Current assignee: Electronics and Telecommunications Research Institute ETRI; Kyung Hee University
Priority date: 2019-08-13
Filing date: 2020-08-13
Publication date: 2022-05-27
Also published as: KR20210019978A

Abstract

A method, apparatus, and recording medium for encoding/decoding an image by using partitions are disclosed. Various prediction methods and prediction modes may be used for prediction for a block. When a block is partitioned, information related to the partition, such as information indicating whether the partition is executed and information specifying the type of the partition, is signaled. Further, when partitions are applied to a block, available prediction methods and available prediction modes may be limited when predicting the block. For optimization of signaling, a plurality of pieces of information related to prediction may be signaled, wherein the plurality of pieces of information may have an interdependent relationship; and in some cases, other pieces of information may be derived as a specific value according to the value of one piece of information, and an operation of signaling the other pieces of information may be omitted. Various methods of efficiently signaling various pieces of information based on the constraints and the interdependent relationships may be provided.

Description

Method, apparatus and recording medium for encoding/decoding image by using partition

The present application claims the benefit of korean patent application No. 10-2019-.

Technical Field

The present disclosure generally relates to a method, apparatus, and storage medium for image encoding/decoding. More particularly, the present disclosure relates to a method, apparatus, and storage medium for image encoding/decoding using partitions.

Background

With the continuous development of the information and communication industry, broadcasting services supporting High Definition (HD) resolution have been popularized throughout the world. Through this popularity, a large number of users have become accustomed to high resolution and high definition images and/or videos.

In order to meet the demand of users for high definition, a large number of mechanisms have accelerated the development of next-generation imaging devices. In addition to high definition TV (hdtv) and Full High Definition (FHD) TV, user interest in UHD TV has also increased, where the resolution of UHD TV is more than four times the resolution of Full High Definition (FHD) TV. With the increase of interest thereof, image encoding/decoding techniques for images with higher resolution and higher definition are now required.

As an image compression technique, there are various techniques (such as an inter-prediction technique, an intra-prediction technique, a transform, a quantization technique, and an entropy coding technique).

The inter prediction technique is a technique for predicting values of pixels included in a current picture using a picture before the current picture and/or a picture after the current picture. The intra prediction technique is a technique for predicting values of pixels included in a current picture using information on the pixels in the current picture. The transform and quantization techniques may be techniques for compressing the energy of the residual image. Entropy coding techniques are techniques for assigning short codewords to frequently occurring values and long codewords to less frequently occurring values.

By utilizing these image compression techniques, data on an image can be efficiently compressed, transmitted, and stored.

Disclosure of Invention

Technical problem

Embodiments are directed to a prediction method for a sub-partition in intra prediction of image coding.

Embodiments are directed to an apparatus and method of configuring a prediction signal for a sub-partition in intra prediction for image coding.

Technical scheme

According to an aspect, there is provided a decoding method comprising: determining a prediction mode for a target block; and performing prediction for the target block using the determined prediction mode.

Advantageous effects

In intra prediction for image coding, a prediction method for sub-partitions is provided.

In intra prediction for image coding, an apparatus and method for configuring prediction information for sub-partitions are provided.

In intra prediction for image encoding, prediction information for efficient intra prediction is configured, and thus encoding efficiency may be improved.

In the implementation of intra prediction for image encoding, prediction information for intra prediction is changed, and thus encoding efficiency may be improved.

By configuration and change of the prediction information, compressibility of image coding can be improved.

Drawings

Fig. 1 is a block diagram showing a configuration of an embodiment of an encoding apparatus to which the present disclosure is applied;

fig. 2 is a block diagram showing a configuration of an embodiment of a decoding apparatus to which the present disclosure is applied;

fig. 3 is a diagram schematically showing a partition structure of an image when the image is encoded and decoded;

fig. 4 is a diagram illustrating a form of a prediction unit that a coding unit can include;

fig. 5 is a diagram showing a form of a transform unit that can be included in an encoding unit;

FIG. 6 illustrates partitioning of blocks according to an example;

FIG. 7 is a diagram for explaining an embodiment of an intra prediction process;

fig. 8 is a diagram illustrating reference samples used in an intra prediction process;

fig. 9 is a diagram for explaining an embodiment of an inter prediction process;

FIG. 10 illustrates spatial candidates according to an embodiment;

fig. 11 illustrates an order of adding motion information of spatial candidates to a merge list according to an embodiment;

FIG. 12 illustrates a transform and quantization process according to an example;

FIG. 13 illustrates a diagonal scan according to an example;

FIG. 14 shows a horizontal scan according to an example;

FIG. 15 shows a vertical scan according to an example;

fig. 16 is a configuration diagram of an encoding device according to an embodiment;

Fig. 17 is a configuration diagram of a decoding apparatus according to an embodiment;

FIG. 18 illustrates an ISP for partitioning a target block into two sub-blocks, according to an example;

FIG. 19 illustrates an ISP for partitioning a target block into four sub-blocks, according to an example;

fig. 20 shows a MIP according to an example;

fig. 21 illustrates available intra prediction modes depending on whether sub-partitions are to be applied or not, according to an example;

fig. 22 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method according to an embodiment;

fig. 23 illustrates a syntax structure for signaling pieces of information related to an intra prediction method according to an example;

fig. 24 illustrates a determination of whether other flags and other indices and values of the other flags and other indices are to be signaled according to values of MIP flags according to an example;

fig. 25 illustrates a method for setting a specific intra prediction mode to be unavailable according to an application of a sub-partition according to an embodiment;

fig. 26 illustrates a method for setting a plane mode to unavailable according to an application of an ISP according to an embodiment;

fig. 27 illustrates a method for setting a DC mode to unavailable according to an application of an ISP according to an embodiment;

fig. 28 illustrates a method for setting a non-directional intra prediction mode to be unavailable according to an application of an ISP according to an embodiment;

Fig. 29 illustrates a method for setting some of a plurality of directional intra-prediction modes, which are specified according to a predefined condition, as unavailable according to an application of an ISP according to an embodiment;

fig. 30 illustrates a method for setting a wide-angle mode to be unavailable according to an application of an ISP according to an embodiment;

fig. 31 illustrates a method for setting a planar mode and a directional intra prediction mode with an odd number as unavailable according to an application of an ISP according to an embodiment;

fig. 32 illustrates a signaling method when a specific intra prediction mode is not available in an ISP according to an embodiment;

fig. 33 illustrates a signaling method when a non-planar token is not used in an ISP according to an embodiment;

fig. 34 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method according to an embodiment;

fig. 35 illustrates a method for preferentially signaling non-planar flags according to an embodiment;

fig. 36 illustrates another method for preferentially signaling non-planar flags according to an embodiment;

fig. 37 illustrates a method for determining whether an operation of signaling information related to an MPM will be performed when a non-planar flag is preferentially signaled, according to an embodiment;

Fig. 38 illustrates another method for determining whether an operation of signaling information related to an MPM will be performed when a non-planar flag is preferentially signaled according to an embodiment;

fig. 39 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when a non-planar flag is preferentially signaled according to an embodiment;

fig. 40 is a flowchart illustrating another method for signaling pieces of information related to an intra prediction method when a non-planar flag is preferentially signaled according to an embodiment;

fig. 41 illustrates a method for signaling information related to a specific intra prediction method according to whether a planar mode will be used when a non-planar flag is preferentially signaled, according to an embodiment;

fig. 42 illustrates a method for signaling MRL-related information according to whether a planar mode will be used when a non-planar flag is preferentially signaled, according to an embodiment;

fig. 43 illustrates a method for signaling information related to an ISP according to whether a planar mode will be used when a non-planar flag is preferentially signaled according to an embodiment;

Fig. 44 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when a non-plane flag is preferentially signaled or when a plane mode is not available in an MRL, according to an embodiment;

fig. 45 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when a non-plane flag is preferentially signaled and a plane mode is not available in an MRL according to an embodiment;

fig. 46 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when an MPM flag is preferentially signaled, according to an embodiment;

fig. 47 illustrates a method for determining whether an operation of signaling MIP-related information will be performed based on a non-planar flag when the non-planar flag is preferentially signaled, according to an embodiment;

fig. 48 illustrates another method for determining whether an operation of signaling MIP-related information will be performed based on a non-planar flag when the non-planar flag is preferentially signaled, according to an embodiment;

fig. 49 illustrates a method for determining whether an operation of signaling MIP-related information will be performed based on an MPM flag when the MPM flag is preferentially signaled, according to an embodiment;

Fig. 50 is a flowchart illustrating a method for signaling information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP will be performed based on a preferentially signaled non-planar flag, according to an embodiment;

fig. 51 is a flowchart illustrating another method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP will be performed based on a non-planar flag that is preferentially signaled according to an embodiment;

fig. 52 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on an MPM flag that is preferentially signaled according to an embodiment;

fig. 53 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on a non-plane flag that is preferentially signaled and a plane mode is not available in an ISP according to an embodiment;

fig. 54 is a flowchart illustrating another method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP will be performed based on a non-plane flag that is preferentially signaled and a plane mode is not available in an ISP, according to an embodiment;

Fig. 55 is a flowchart illustrating still another method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP will be performed based on a non-plane flag that is preferentially signaled and a plane mode is not available in an ISP according to an embodiment;

fig. 56 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP will be performed based on the MPM flag that is preferentially signaled and a plane mode is not available in the ISP, according to an embodiment;

fig. 57 shows a first syntax structure according to an embodiment;

fig. 58 illustrates a second syntax structure according to an embodiment;

FIG. 59 shows a third syntax structure in accordance with an embodiment;

FIG. 60 illustrates a front segment of a fourth syntax structure in accordance with an embodiment;

FIG. 61 illustrates a later section of a fourth syntax structure in accordance with an embodiment;

FIG. 62 illustrates a front segment of a fifth syntax structure according to an embodiment;

FIG. 63 illustrates a later section of a fifth syntax structure in accordance with an embodiment;

FIG. 64 illustrates a front section of a sixth syntax structure according to an embodiment;

FIG. 65 shows a later section of a sixth syntax structure according to an embodiment;

Fig. 66 shows a front section of a seventh syntax structure according to an embodiment;

fig. 67 shows a later section of a seventh syntax structure according to an embodiment;

FIG. 68 shows a front section of an eighth syntax structure in accordance with an embodiment;

FIG. 69 illustrates a back section of an eighth syntax structure in accordance with an embodiment;

FIG. 70 illustrates a front section of a ninth syntax structure in accordance with an embodiment;

FIG. 71 shows a back section of a ninth syntax structure in accordance with an embodiment;

FIG. 72 shows a front section of a tenth syntax structure according to an embodiment;

fig. 73 shows a latter section of a tenth syntax structure according to the embodiment;

FIG. 74 illustrates a front segment of an eleventh syntax structure according to an embodiment;

fig. 75 shows a later section of an eleventh syntax structure according to an embodiment;

FIG. 76 shows a front section of a twelfth syntax structure according to an embodiment;

fig. 77 shows a later section of a twelfth syntax structure according to an embodiment;

fig. 78 shows a front section of a thirteenth syntax structure according to the embodiment;

fig. 79 shows a latter section of a thirteenth syntax structure according to the embodiment;

FIG. 80 illustrates a front section of a fourteenth syntax structure according to an embodiment;

FIG. 81 shows a later section of a fourteenth syntax structure according to an embodiment;

figure 82 shows a first signalling structure according to an embodiment;

Figure 83 shows a second signalling structure according to an embodiment;

figure 84 shows a third signaling structure in accordance with an embodiment;

figure 85 shows a fourth signaling structure in accordance with an embodiment;

fig. 86 illustrates a fifth signaling structure according to an embodiment;

fig. 87 shows a sixth signaling structure according to an embodiment;

fig. 88 shows a seventh signaling structure according to an embodiment;

fig. 89 shows an eighth signaling structure according to an embodiment;

fig. 90 shows a ninth signaling structure according to an embodiment;

fig. 91 shows a tenth signaling structure according to an embodiment;

fig. 92 shows an eleventh signaling structure according to an embodiment;

fig. 93 illustrates a configuration of an intra prediction unit according to an embodiment;

fig. 94 illustrates a configuration of an intra prediction execution unit according to an embodiment;

fig. 95 illustrates a first configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 96 shows a second configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 97 illustrates a third configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 98 illustrates a fourth configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 99 illustrates a fifth configuration of an intra prediction mode information signaling unit according to an embodiment;

Fig. 100 shows a sixth configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 101 shows a seventh configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 102 illustrates an eighth configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 103 illustrates a ninth configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 104 shows a tenth configuration of an intra prediction mode information signaling unit according to the embodiment;

fig. 105 shows an eleventh configuration of an intra prediction mode information signaling unit according to an embodiment;

fig. 106 is a flowchart illustrating a target block prediction method and a bitstream generation method according to an embodiment; and

fig. 107 is a flowchart illustrating a target block prediction method using a bitstream according to an embodiment.

Detailed Description

The present invention may be variously modified and may have various embodiments, and specific embodiments will be described in detail below with reference to the accompanying drawings. It should be understood, however, that these examples are not intended to limit the invention to the particular forms disclosed, but to include all changes, equivalents, and modifications that are within the spirit and scope of the invention.

The following exemplary embodiments will be described in detail with reference to the accompanying drawings showing specific embodiments. These embodiments are described so that those of ordinary skill in the art to which this disclosure pertains will be readily able to practice them. It should be noted that the various embodiments are distinct from one another, but are not necessarily mutually exclusive. For example, particular shapes, structures, and characteristics described herein may be implemented as one embodiment without departing from the spirit and scope of other embodiments associated with the other embodiments. Further, it is to be understood that the location or arrangement of individual components within each disclosed embodiment can be modified without departing from the spirit and scope of the embodiments. Therefore, the appended detailed description is not intended to limit the scope of the disclosure, and the scope of exemplary embodiments is defined only by the appended claims and equivalents thereof, as they are properly described.

In the drawings, like numerals are used to designate the same or similar functions in various respects. The shapes, sizes, and the like of components in the drawings may be exaggerated for clarity of the description.

Terms such as "first" and "second" may be used to describe various components, but the components are not limited by the terms. The terms are only used to distinguish one component from another component. For example, a first component may be termed a second component without departing from the scope of the present description. Similarly, the second component may be referred to as the first component. The term "and/or" may include a combination of multiple related items or any one of multiple related items.

It will be understood that when an element is referred to as being "connected" or "coupled" to another element, the two elements may be directly connected or coupled to each other or intervening elements may be present between the two elements. On the other hand, it will be understood that when components are referred to as being "directly connected or coupled", there are no intervening components between the two components.

Further, components described in the embodiments are independently illustrated to indicate different feature functions, but this does not mean that each component is formed of a separate piece of hardware or software. That is, a plurality of components are individually arranged and included for convenience of description. For example, at least two of the plurality of components may be integrated into a single component. Instead, one component may be divided into a plurality of components. Embodiments in which a plurality of components are integrated or embodiments in which some components are separated are included in the scope of the present specification as long as they do not depart from the essence of the present specification.

Furthermore, in exemplary embodiments, the expression that a component "includes" a specific component means that another component may be included within the scope of practical or technical spirit of the exemplary embodiments, but does not exclude the presence of components other than the specific component.

The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular references include plural references unless the context specifically indicates the contrary. In this specification, it is to be understood that terms such as "including" or "having" are only intended to indicate that there are features, numbers, steps, operations, components, parts, or combinations thereof, and are not intended to preclude the possibility that one or more other features, numbers, steps, operations, components, parts, or combinations thereof will be present or added. That is, in the present invention, the expression that a component described "includes" a specific component means that another component may be included in the scope of the practice of the present invention or the technical spirit of the present invention, but does not exclude the presence of components other than the specific component.

Some components of the present invention are not essential components for performing essential functions but may be optional components only for improving performance. An embodiment may be implemented using only the necessary components to implement the essence of the embodiment. For example, a structure including only necessary components (not including only optional components for improving performance) is also included in the scope of the embodiments.

The embodiments will be described in detail below with reference to the accompanying drawings so that those skilled in the art to which the embodiments pertain can easily implement the embodiments. In the following description of the embodiments, a detailed description of known functions or configurations incorporated herein will be omitted. In addition, the same reference numerals are used to designate the same components throughout the drawings, and repeated description of the same components will be omitted.

Hereinafter, "image" may represent a single picture constituting a video, or may represent the video itself. For example, "encoding and/or decoding of an image" may mean "encoding and/or decoding of a video", and may also mean "encoding and/or decoding of any one of a plurality of images constituting a video".

Hereinafter, the terms "video" and "moving picture" may be used to have the same meaning and may be used interchangeably with each other.

Hereinafter, the target image may be an encoding target image that is a target to be encoded and/or a decoding target image that is a target to be decoded. Further, the target image may be an input image input to the encoding apparatus or an input image input to the decoding apparatus. Also, the target image may be a current image, i.e., a target that is currently to be encoded and/or decoded. For example, the terms "target image" and "current image" may be used to have the same meaning and may be used interchangeably with each other.

Hereinafter, the terms "image", "picture", "frame", and "screen" may be used to have the same meaning and may be used interchangeably with each other.

Hereinafter, the target block may be an encoding target block (i.e., a target to be encoded) and/or a decoding target block (i.e., a target to be decoded). Furthermore, the target block may be a current block, i.e. a target that is currently to be encoded and/or decoded. Here, the terms "target block" and "current block" may be used to have the same meaning and may be used interchangeably with each other. The current block may represent an encoding target block that is an encoding target during encoding and/or a decoding target block that is a decoding target during decoding. Further, the current block may be at least one of an encoding block, a prediction block, a residual block, and a transform block.

Hereinafter, the terms "block" and "unit" may be used to have the same meaning and may be used interchangeably with each other. Alternatively, a "block" may represent a particular unit.

Hereinafter, the terms "region" and "fragment" are used interchangeably with each other.

In the following embodiments, particular information, data, flags, indices, elements, and attributes may have their respective values. A value of "0" corresponding to each of the information, data, flags, indices, elements, and attributes may indicate false, logical false, or a first predefined value. In other words, the values "0", false, logical false, and the first predefined value may be used interchangeably with each other. A value of "1" corresponding to each of the information, data, flags, indices, elements, and attributes may indicate true, logically true, or a second predefined value. In other words, the values "1", true, logically true, and second predefined values may be used interchangeably with each other.

When a variable such as i or j is used to indicate a row, column, or index, the value i may be an integer 0 or an integer greater than 0, or may be an integer 1 or an integer greater than 1. In other words, in embodiments, each of the rows, columns, and indices may count from 0, or may count from 1.

In embodiments, the term "one or more" or the term "at least one" may mean the term "a plurality". The term "one or more" or the term "at least one" may be used interchangeably with "plurality".

Hereinafter, terms to be used in the embodiments will be described.

An encoder: the encoder represents an apparatus for performing encoding. That is, the encoder may represent an encoding apparatus.

A decoder: the decoder represents means for performing decoding. That is, the decoder may represent a decoding apparatus.

A unit: the "unit" may represent a unit of image encoding and decoding. The terms "unit" and "block" may be used to have the same meaning and may be used interchangeably with each other.

The cell may be an M × N array of samples. Each of M and N may be a positive integer. The cells may generally represent a two-dimensional form of an array of samples.

During the encoding and decoding of an image, a "unit" may be a region generated by partitioning an image. In other words, a "cell" may be a region designated in one image. A single image may be partitioned into multiple cells. Alternatively, one image may be partitioned into sub-parts, and a unit may represent each partitioned sub-part when encoding or decoding is performed on the partitioned sub-parts.

During the encoding and decoding of the image, a predefined processing may be performed on each unit according to the type of unit.

Unit types may be classified into macro-units, Coding Units (CUs), Prediction Units (PUs), residual units, Transform Units (TUs), etc., according to function. Alternatively, the unit may represent a block, a macroblock, a coding tree unit, a coding tree block, a coding unit, a coding block, a prediction unit, a prediction block, a residual unit, a residual block, a transform unit, a transform block, and the like according to functions. For example, a target unit that is a target of encoding and/or decoding may be at least one of a CU, a PU, a residual unit, and a TU.

The term "unit" may denote information including a luminance (luma) component block, a chrominance (chroma) component block corresponding to the luminance component block, and syntax elements for the respective blocks, such that the unit is designated to be distinguished from the blocks.

The size and shape of the cells can be implemented differently. Further, the cells may have any of a variety of sizes and shapes. Specifically, the shape of the cell may include not only a square but also a geometric shape (such as a rectangle, a trapezoid, a triangle, and a pentagon) that can be represented in two dimensions (2D).

In addition, the unit information may include one or more of a type of the unit, a size of the unit, a depth of the unit, an encoding order of the unit, a decoding order of the unit, and the like. For example, the type of the unit may indicate one of a CU, a PU, a residual unit, and a TU.

A unit may be partitioned into sub-units, each sub-unit having a size smaller than the size of the associated unit.

Depth: depth may represent the degree to which a cell is partitioned. Further, the depth of a cell may indicate a level at which the corresponding cell exists when the cell is represented by the tree structure.

The unit partition information may comprise a depth indicating a depth of the unit. The depth may indicate the number of times a cell is partitioned and/or the extent to which the cell is partitioned.

In the tree structure, the depth of the root node can be considered to be the smallest and the depth of the leaf nodes the largest. The root node may be the highest (top) node. The leaf node may be the lowest node.

A single unit may be hierarchically partitioned into a plurality of sub-units, while the single unit has tree structure based depth information. In other words, a unit and a child unit generated by partitioning the unit may correspond to a node and a child node of the node, respectively. Each partitioned sub-unit may have a unit depth. Since the depth indicates the number of times the unit is partitioned and/or the degree to which the unit is partitioned, the partition information of the sub-unit may include information on the size of the sub-unit.

In the tree structure, the top node may correspond to the initial node before partitioning. The top node may be referred to as the "root node". Further, the root node may have the smallest depth value. Here, the depth of the top node may be level "0".

A node with a depth of level "1" may represent a unit generated when an initial unit is partitioned once. A node with a depth of level "2" may represent a unit generated when an initial unit is partitioned twice.

A leaf node with a depth of level "n" may represent a unit generated when an initial unit is partitioned n times.

A leaf node may be the bottom node that cannot be partitioned further. The depth of a leaf node may be a maximum level. For example, the predefined value for the maximum level may be 3.

the-QT depth may represent the depth for a quad-partition. BT depth may represent depth for a bipartite partition. The TT depth may represent a depth for a tri-partition.

-sampling points: the samples may be elementary units that constitute a block. Available from 0 to 2 according to the bit depth (Bd)^Bd-a value of 1 to represent a sample point.

The samples may be pixels or pixel values.

In the following, the terms "pixel" and "sample" may be used with the same meaning and may be used interchangeably with each other.

Code Tree Unit (CTU): a CTU may be composed of a single luma component (Y) coding tree block and two chroma component (Cb, Cr) coding tree blocks associated with the luma component coding tree block. Further, the CTU may represent information including the above-described blocks and syntax elements for each block.

-each Coding Tree Unit (CTU) may be partitioned using one or more partitioning methods, such as Quadtree (QT), Binary Tree (BT) and Ternary Tree (TT), in order to configure sub-units, such as coding units, prediction units and transform units. The quadtree may represent a quadtree. Further, each coding tree unit may be partitioned using a multi-type tree (MTT) using one or more partitioning methods.

"CTU" may be used as a term designating a pixel block as a processing unit in an image decoding and encoding process, such as in the case of partitioning an input image.

Coded Tree Block (CTB): "CTB" may be used as a term designating any one of a Y coding tree block, a Cb coding tree block, and a Cr coding tree block.

Adjacent blocks: the neighboring blocks (or neighboring blocks) may represent blocks adjacent to the target block. The neighboring blocks may represent reconstructed neighboring blocks.

Hereinafter, the terms "adjacent block" and "adjacent block" may be used to have the same meaning and may be used interchangeably with each other.

The neighboring blocks may represent reconstructed neighboring blocks.

Spatially adjacent blocks: the spatially neighboring block may be a block spatially adjacent to the target block. The neighboring blocks may include spatially neighboring blocks.

The target block and the spatially neighboring blocks may be comprised in the target picture.

Spatially neighboring blocks may represent blocks whose boundaries are in contact with the target block or blocks which are located within a predetermined distance from the target block.

The spatially neighboring blocks may represent blocks adjacent to the vertex of the target block. Here, the blocks adjacent to the vertex of the target block may represent blocks vertically adjacent to an adjacent block horizontally adjacent to the target block or blocks horizontally adjacent to an adjacent block vertically adjacent to the target block.

Temporal neighboring blocks: the temporally adjacent block may be a block temporally adjacent to the target block. The neighboring blocks may include temporally neighboring blocks.

The temporally adjacent blocks may comprise co-located blocks (col blocks).

A col block may be a block in a previously reconstructed co-located picture (col picture). The location of the col block in the col picture may correspond to the location of the target block in the target picture. Alternatively, the location of the col block in the col picture may be equal to the location of the target block in the target picture. The col picture may be a picture included in the reference picture list.

The temporal neighboring blocks may be blocks temporally adjacent to spatially neighboring blocks of the target block.

Prediction mode: the prediction mode may be information indicating a mode in which encoding and/or decoding is performed for intra prediction or a mode in which encoding and/or decoding is performed for inter prediction.

A prediction unit: the prediction unit may be a basic unit for prediction such as inter prediction, intra prediction, inter compensation, intra compensation, and motion compensation.

A single prediction unit may be divided into multiple partitions or sub-prediction units of smaller size. The plurality of partitions may also be basic units in performing prediction or compensation. The partition generated by dividing the prediction unit may also be the prediction unit.

Prediction unit partitioning: the prediction unit partition may be a shape into which the prediction unit is divided.

Reconstructed neighboring cells: the reconstructed neighboring cell may be a cell that is neighboring the target cell and has been decoded and reconstructed.

The reconstructed neighboring cells may be cells that are spatially adjacent to the target cell or temporally adjacent to the target cell.

The reconstructed spatially neighboring units may be units comprised in the target picture that have been reconstructed by encoding and/or decoding.

The reconstructed temporal neighboring cells may be cells comprised in the reference image that have been reconstructed by encoding and/or decoding. The position of the reconstructed temporally neighboring cell in the reference image may be the same as the position of the target cell in the target picture or may correspond to the position of the target cell in the target picture. Further, the reconstructed temporal neighboring cell may be a block neighboring the corresponding block in the reference image. Here, the position of the corresponding block in the reference image may correspond to the position of the target block in the target image. Here, the fact that the positions of the blocks correspond to each other may mean that the positions of the blocks are the same as each other, may mean that one block is included in another block, or may mean that one block occupies a specific position in another block.

And (3) sub-picture: a picture may be divided into one or more sub-pictures. A sprite may be composed of one or more parallel block rows and one or more parallel block columns.

A sprite may be a region in a picture that has a square or rectangular (i.e., non-square, rectangular) shape. Further, a sprite may include one or more CTUs.

A single sprite may comprise one or more parallel blocks, one or more tiles (swick) and/or one or more stripes.

A parallel block: a parallel block may be a region in a picture having a square or rectangular (i.e., non-square, rectangular) shape.

A parallel block may comprise one or more CTUs.

A parallel block may be partitioned into one or more partitions.

Partitioning: a block may represent one or more rows of CTUs in a parallel block.

A parallel block may be partitioned into one or more partitions. Each partition may include one or more rows of CTUs.

Parallel blocks that are not partitioned into two parts may also represent partitions.

Strip: a stripe may comprise one or more parallel blocks in a picture. Optionally, a stripe may comprise one or more partitions of parallel blocks.

Parameter set: the parameter set may correspond to header information in an internal structure of the bitstream.

The parameter set may include at least one of a Video Parameter Set (VPS), a Sequence Parameter Set (SPS), a Picture Parameter Set (PPS), an Adaptive Parameter Set (APS), a Decoding Parameter Set (DPS), and the like.

The information signaled by each parameter set may be applied to a picture referring to the corresponding parameter set. For example, information in the VPS may be applied to pictures that reference the VPS. Information in the SPS may be applied to pictures that reference the SPS. Information in the PPS may be applied to pictures that reference the PPS.

Each parameter set may refer to a higher parameter set. For example, a PPS may reference an SPS. SPS may refer to VPS.

Further, the parameter set may include a parallel block group, slice header information, and parallel block header information. The parallel block group may be a group including a plurality of parallel blocks. Further, the meaning of "parallel block group" may be the same as that of "stripe".

And (3) rate distortion optimization: an encoding device may use rate-distortion optimization to provide high encoding efficiency by utilizing a combination of: a size of a Coding Unit (CU), a prediction mode, a size of a Prediction Unit (PU), motion information, and a size of a Transform Unit (TU).

The rate-distortion optimization scheme may calculate the rate-distortion cost of each combination to select the optimal combination from the combinations. The rate-distortion cost may be calculated using the equation "D + λ R". In general, the combination that minimizes the rate-distortion cost may be selected as the optimal combination under the rate-distortion optimization scheme.

D may represent distortion. D may be the average of the squares of the differences between the original transform coefficients and the reconstructed transform coefficients in the transform unit (i.e., the mean square error).

-R may represent the rate, which may represent the bit rate using the relevant context information.

- λ represents the lagrange multiplier. R may include not only coding parameter information such as a prediction mode, motion information, and a coding block flag, but also bits generated as a result of coding transform coefficients.

The coding device may perform processes such as inter-and/or intra-prediction, transformation, quantization, entropy coding, inverse quantization (dequantization) and/or inverse transformation in order to calculate the exact D and R. These processes can add significant complexity to the encoding device.

Bit stream: the bitstream may represent a stream of bits including encoded image information.

And (3) analysis: parsing may be a decision on the value of a syntax element made by performing entropy decoding on the bitstream. Alternatively, the term "parsing" may denote such entropy decoding itself.

Symbol: the symbol may be at least one of a syntax element, an encoding parameter, and a transform coefficient of the encoding target unit and/or the decoding target unit. Further, the symbol may be a target of entropy encoding or a result of entropy decoding.

Reference picture: the reference picture may be an image that is unit-referenced in order to perform inter prediction or motion compensation. Alternatively, the reference picture may be an image including a reference unit that is referred to by the target unit in order to perform inter prediction or motion compensation.

Hereinafter, the terms "reference picture" and "reference image" may be used to have the same meaning and may be used interchangeably with each other.

Reference picture list: the reference picture list may be a list including one or more reference pictures used for inter prediction or motion compensation.

Types of the reference picture list may include a combination List (LC), list 0(L0), list 1(L1), list 2(L3), list 3(L3), and the like.

For inter prediction, one or more reference picture lists may be used.

Inter prediction indicator: the inter prediction indicator may indicate an inter prediction direction for the target unit. The inter prediction may be one of unidirectional prediction and bidirectional prediction. Alternatively, the inter prediction indicator may represent the number of reference pictures used to generate the prediction unit of the target unit. Alternatively, the inter prediction indicator may represent the number of prediction blocks used for inter prediction or motion compensation of the target unit.

Prediction list utilization flag: the prediction list utilization flag may indicate whether at least one reference picture in a particular reference picture list is used to generate a prediction unit.

-deriving the inter prediction indicator using the prediction list utilization flag. Instead, the prediction list utilization flag may be derived using the inter prediction indicator. For example, a case where the prediction list indicates "0" (as a first value) with the flag may indicate that, for the target unit, the reference picture in the reference picture list is not used to generate the prediction block. The case where the prediction list indicates "1" (as a second value) with the flag may indicate that, for the target unit, the prediction unit is generated using the reference picture list.

Reference picture index: the reference picture index may be an index indicating a specific reference picture in the reference picture list.

Picture Order Count (POC): the POC value of a picture may represent an order in which the corresponding picture is displayed.

Motion Vector (MV): the motion vector may be a 2D vector for inter prediction or motion compensation. The motion vector may represent an offset between the target image and the reference image.

For example, may be represented by a symbol such as (mv)_x，mv_y) Represents the MV. mv_xCan indicate the horizontal component, mv_yA vertical component may be indicated.

The search range is as follows: the search range may be a 2D region in which a search for MVs is performed during inter prediction. For example, the size of the search range may be M × N. M and N may be positive integers, respectively.

Motion vector candidates: the motion vector candidate may be a block that is a prediction candidate when the motion vector is predicted or a motion vector of a block that is a prediction candidate.

The motion vector candidate may be comprised in a motion vector candidate list.

Motion vector candidate list: the motion vector candidate list may be a list configured using one or more motion vector candidates.

Motion vector candidate index: the motion vector candidate index may be an indicator for indicating a motion vector candidate in the motion vector candidate list. Alternatively, the motion vector candidate index may be an index of a motion vector predictor.

Motion information: the motion information may be information including at least one of a reference picture list, a reference picture, a motion vector candidate index, a merge candidate, and a merge index, and a motion vector, a reference picture index, and an inter prediction indicator.

Merging the candidate lists: the merge candidate list may be a list using one or more merge candidate configurations.

Merging candidates: the merge candidate may be a spatial merge candidate, a temporal merge candidate, a combined bi-predictive merge candidate, a history-based candidate, a candidate based on an average of the two candidates, a zero merge candidate, etc. The merge candidate may include an inter prediction indicator, and may include motion information such as prediction type information, a reference picture index for each list, a motion vector, a prediction list utilization flag, and an inter prediction indicator.

Merging indexes: the merge index may be an indicator for indicating a merge candidate in the merge candidate list.

The merging index may indicate a reconstruction unit used for deriving the merging candidate among reconstruction units spatially neighboring the target unit and reconstruction units temporally neighboring the target unit.

The merge index may indicate at least one of pieces of motion information of the merge candidates.

A transformation unit: the transform unit may be a basic unit of residual signal encoding and/or residual signal decoding, such as transform, inverse transform, quantization, inverse quantization, transform coefficient encoding, and transform coefficient decoding. A single transform unit may be partitioned into multiple sub-transform units having smaller sizes. Here, the transform may include one or more of a primary transform and a secondary transform, and the inverse transform may include one or more of a primary inverse transform and a secondary inverse transform.

Zooming: scaling may refer to the process of multiplying a factor by a transform coefficient level.

-as a result of scaling the transform coefficient level, transform coefficients may be generated. Scaling may also be referred to as "inverse quantization".

Quantization Parameter (QP): the quantization parameter may be a value used to generate a transform coefficient level for a transform coefficient in quantization. Alternatively, the quantization parameter may also be a value used to generate a transform coefficient by scaling the transform coefficient level in inverse quantization. Alternatively, the quantization parameter may be a value mapped to a quantization step.

Delta (Delta) quantization parameter: the delta quantization parameter may represent a difference between the quantization parameter of the target unit and the predicted quantization parameter.

Scanning: scanning may refer to a method of arranging the order of coefficients in a cell, block, or matrix. For example, a method for arranging a 2D array in the form of a one-dimensional (1D) array may be referred to as "scanning". Alternatively, the method for arranging the 1D array in the form of a 2D array may also be referred to as "scanning" or "inverse scanning".

Transform coefficients: the transform coefficient may be a coefficient value generated when the encoding apparatus performs the transform. Alternatively, the transform coefficient may be a coefficient value generated when the decoding apparatus performs at least one of entropy decoding and inverse quantization.

Quantized levels generated by applying quantization to the transform coefficients or the residual signal or quantized transform coefficient levels may also be included in the meaning of the term "transform coefficients".

Level of quantization: the level of quantization may be a value generated when the encoding apparatus performs quantization on the transform coefficient or the residual signal. Alternatively, the quantized level may be a value that is a target of inverse quantization when the decoding apparatus performs inverse quantization.

The quantized transform coefficient levels as a result of the transform and quantization may also be included in the meaning of quantized levels.

Non-zero transform coefficients: the non-zero transform coefficient may be a transform coefficient having a value other than 0, or may be a transform coefficient level having a value other than 0. Alternatively, the non-zero transform coefficient may be a transform coefficient whose value is not 0 in magnitude, or may be a transform coefficient level whose value is not 0 in magnitude.

Quantization matrix: the quantization matrix may be a matrix used in a quantization process or an inverse quantization process in order to improve subjective image quality or objective image quality of an image. The quantization matrix may also be referred to as a "scaling list".

Quantization matrix coefficients: the quantization matrix coefficient may be each element in the quantization matrix. The quantized matrix coefficients may also be referred to as "matrix coefficients".

Default matrix: the default matrix may be a quantization matrix predefined by the encoding device and the decoding device.

Non-default matrix: the non-default matrix may be a quantization matrix that is not predefined by the encoding device and the decoding device. The non-default matrix may represent a quantization matrix signaled by a user from an encoding device to a decoding device.

Most Probable Mode (MPM): the MPM may represent an intra prediction mode in which a high probability is used for intra prediction for the target block.

The encoding apparatus and the decoding apparatus may determine one or more MPMs based on the encoding parameters related to the target block and the attributes of the entity related to the target block.

The encoding device and the decoding device may determine the one or more MPMs based on an intra prediction mode of the reference block. The reference block may include a plurality of reference blocks. The plurality of reference blocks may include a spatially neighboring block adjacent to the left side of the target block and a spatially neighboring block adjacent to the upper side of the target block. In other words, one or more different MPMs may be determined according to which intra prediction modes have been used for the reference block.

One or more MPMs can be determined in the same way in both the encoding device and the decoding device. That is, the encoding apparatus and the decoding apparatus may share the same MPM list including one or more MPMs.

MPM List: the MPM list may be a list including one or more MPMs. The number of one or more MPMs in the MPM list may be predefined.

MPM indicator: the MPM indicator may indicate an MPM to be used for intra prediction for the target block among one or more MPMs in the MPM list. For example, the MPM indicator may be an index for an MPM list.

Since the MPM list is determined in the same manner in both the encoding device and the decoding device, it may not be necessary to transmit the MPM list itself from the encoding device to the decoding device.

The MPM indicator may be signaled from the encoding device to the decoding device. Since the MPM indicator is signaled, the decoding apparatus may determine an MPM to be used for intra prediction for the target block among MPMs in the MPM list.

MPM usage indicator: the MPM usage indicator may indicate whether an MPM usage mode is to be used for prediction for the target block. The MPM use mode may be a mode that determines an MPM to be used for intra prediction for the target block using the MPM list.

The MPM usage indicator may be signaled from the encoding device to the decoding device.

Signaling: "signaling" may mean that information is sent from an encoding device to a decoding device. Alternatively, "signaling" may mean that information is included in a bitstream or a recording medium. The information signaled by the encoding device may be used by the decoding device.

The encoding device may generate the encoded information by performing an encoding of the information to be signaled. The encoded information may be transmitted from the encoding device to the decoding device. The decoding apparatus may obtain the information by decoding the transmitted encoded information. Here, the encoding may be entropy encoding, and the decoding may be entropy decoding.

And (3) statistical value: variables, coding parameters, constants, etc. may have calculable values. The statistical value may be a value generated by performing calculation (operation) on a value specifying a target. For example, the statistical value may indicate one or more of an average, a weighted sum, a minimum, a maximum, a mode, a median, and an interpolation of values of a particular variable, a particular encoding parameter, a particular constant, and the like.

Fig. 1 is a block diagram showing a configuration of an embodiment of an encoding apparatus to which the present disclosure is applied.

The encoding device 100 may be an encoder, a video encoding device, or an image encoding device. A video may comprise one or more images (pictures). The encoding apparatus 100 may sequentially encode one or more images of a video.

Referring to fig. 1, the encoding apparatus 100 includes an inter prediction unit 110, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, an entropy encoding unit 150, an inverse quantization (inverse quantization) unit 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.

The encoding apparatus 100 may perform encoding on a target image using an intra mode and/or an inter mode. In other words, the prediction mode of the target block may be one of an intra mode and an inter mode.

Hereinafter, the terms "intra mode", "intra prediction mode", "intra mode", and "intra prediction mode" may be used to have the same meaning and may be used interchangeably with each other.

Hereinafter, the terms "inter mode", "inter prediction mode", "inter mode", and "inter prediction mode" may be used to have the same meaning and may be used interchangeably with each other.

Hereinafter, the term "image" may indicate only a partial image, or may indicate a block. Further, the processing of an "image" may indicate sequential processing of a plurality of blocks.

Further, the encoding apparatus 100 may generate a bitstream including encoded information by encoding the target image, and may output and store the generated bitstream. The generated bitstream may be stored in a computer-readable storage medium and may be streamed over a wired and/or wireless transmission medium.

When the intra mode is used as the prediction mode, the switch 115 may switch to the intra mode. When the inter mode is used as the prediction mode, the switch 115 may switch to the inter mode.

The encoding apparatus 100 may generate a prediction block of a target block. Also, after the prediction block has been generated, the encoding apparatus 100 may encode a residual block for the target block using a residual between the target block and the prediction block.

When the prediction mode is the intra mode, the intra prediction unit 120 may use pixels of a previously encoded/decoded neighboring block adjacent to the target block as reference samples. The intra prediction unit 120 may perform spatial prediction on the target block using the reference sampling points, and may generate prediction sampling points for the target block via the spatial prediction. The prediction samples may represent samples in a prediction block.

The inter prediction unit 110 may include a motion prediction unit and a motion compensation unit.

When the prediction mode is the inter mode, the motion prediction unit may search for a region that best matches the target block in the reference image in the motion prediction process, and may derive a motion vector for the target block and the found region based on the found region. Here, the motion prediction unit may use the search range as a target region for the search.

The reference image may be stored in the reference picture buffer 190. More specifically, when encoding and/or decoding of a reference image has been processed, the encoded and/or decoded reference image may be stored in the reference picture buffer 190.

The reference picture buffer 190 may be a Decoded Picture Buffer (DPB) since decoded pictures are stored.

The motion compensation unit may generate the prediction block for the target block by performing motion compensation using the motion vector. Here, the motion vector may be a two-dimensional (2D) vector for inter prediction. Further, the motion vector may indicate an offset between the target image and the reference image.

When the motion vector has a value other than an integer, the motion prediction unit and the motion compensation unit may generate the prediction block by applying an interpolation filter to a partial region of the reference image. To perform inter prediction or motion compensation, it may be determined which one of a skip mode, a merge mode, an Advanced Motion Vector Prediction (AMVP) mode, and a current picture reference mode corresponds to a method for predicting and compensating for motion of a PU included in a CU based on the CU, and the inter prediction or motion compensation may be performed according to the mode.

The subtractor 125 may generate a residual block, wherein the residual block is a difference between the target block and the prediction block. The residual block may also be referred to as a "residual signal".

The residual signal may be the difference between the original signal and the predicted signal. Alternatively, the residual signal may be a signal generated by transforming or quantizing the difference between the original signal and the prediction signal or a signal generated by transforming and quantizing the difference. The residual block may be a residual signal for a block unit.

The transform unit 130 may generate a transform coefficient by transforming the residual block, and may output the generated transform coefficient. Here, the transform coefficient may be a coefficient value generated by transforming the residual block.

The transformation unit 130 may use one of a plurality of predefined transformation methods when performing the transformation.

The plurality of predefined transform methods may include Discrete Cosine Transform (DCT), Discrete Sine Transform (DST), Karhunen-Loeve transform (KLT), and the like.

The transform method for transforming the residual block may be determined according to at least one of the encoding parameters for the target block and/or the neighboring blocks. For example, the transform method may be determined based on at least one of an inter prediction mode for the PU, an intra prediction mode for the PU, a size of the TU, and a shape of the TU. Alternatively, transform information indicating a transform method may be signaled from the encoding apparatus 100 to the decoding apparatus 200.

When the transform skip mode is used, the transform unit 130 may omit an operation of transforming the residual block.

By performing quantization on the transform coefficients, quantized transform coefficient levels or quantized levels may be generated. Hereinafter, in the embodiment, each of the quantized transform coefficient level and the quantized level may also be referred to as a "transform coefficient".

The quantization unit 140 may generate a quantized transform coefficient level (i.e., a quantized level or a quantized coefficient) by quantizing the transform coefficient according to a quantization parameter. The quantization unit 140 may output the generated quantized transform coefficient levels. In this case, the quantization unit 140 may quantize the transform coefficient using a quantization matrix.

The entropy encoding unit 150 may generate a bitstream by performing probability distribution-based entropy encoding based on the values calculated by the quantization unit 140 and/or the encoding parameter values calculated in the encoding process. The entropy encoding unit 150 may output the generated bitstream.

The entropy encoding unit 150 may perform entropy encoding on information about pixels of an image and information required for decoding the image. For example, information required for decoding an image may include syntax elements and the like.

When entropy coding is applied, fewer bits may be allocated to more frequently occurring symbols and more bits may be allocated to less frequently occurring symbols. Since the symbols are represented by this allocation, the size of the bit string for the target symbol to be encoded can be reduced. Accordingly, the compression performance of video encoding can be improved by entropy encoding.

Also, in order to perform entropy encoding, the entropy encoding unit 150 may use an encoding method such as exponential golomb, Context Adaptive Variable Length Coding (CAVLC), or Context Adaptive Binary Arithmetic Coding (CABAC). For example, entropy encoding unit 150 may perform entropy encoding using a variable length coding/code (VLC) table. For example, the entropy encoding unit 150 may derive a binarization method for the target symbol. Furthermore, entropy encoding unit 150 may derive a probability model for the target symbol/bin. The entropy encoding unit 150 may perform arithmetic encoding using the derived binarization method, probability model, and context model.

The entropy encoding unit 150 may transform the coefficients in the form of 2D blocks into the form of 1D vectors by a transform coefficient scanning method so as to encode the quantized transform coefficient levels.

The encoding parameter may be information required for encoding and/or decoding. The encoding parameter may include information encoded by the encoding apparatus 100 and transmitted from the encoding apparatus 100 to the decoding apparatus, and may also include information that may be derived in an encoding or decoding process. For example, the information sent to the decoding device may include syntax elements.

The encoding parameters may include not only information (or flags or indexes) such as syntax elements encoded by the encoding apparatus and signaled by the encoding apparatus to the decoding apparatus, but also information derived in the encoding or decoding process. In addition, the encoding parameters may include information required to encode or decode the image. For example, the encoding parameters may include at least one of the following, a combination of the following, or statistics: a size of the unit/block, a shape/form of the unit/block, a depth of the unit/block, partition information of the unit/block, a partition structure of the unit/block, information indicating whether the unit/block is partitioned in a quad-tree structure, information indicating whether the unit/block is partitioned in a binary-tree structure, a partition direction of the binary-tree structure (horizontal direction or vertical direction), a partition form of the binary-tree structure (symmetric partition or asymmetric partition), information indicating whether the unit/block is partitioned in a ternary-tree structure, a partition direction of the ternary-tree structure (horizontal direction or vertical direction), a partition form of the ternary-tree structure (symmetric partition or asymmetric partition, etc.), information indicating whether the unit/block is partitioned in a multi-type tree structure, a combination and direction of partitions of the multi-type tree structure (horizontal direction or vertical direction, etc.), and, Partition form of partitions of multi-type tree structure (symmetric partition or asymmetric partition, etc.), partition tree of multi-type tree form (binary tree or ternary tree), prediction type (intra prediction or inter prediction), intra prediction mode/direction, intra luma prediction mode/direction, intra chroma prediction mode/direction, intra partition information, inter partition information, coding block partition flag, prediction block partition flag, transform block partition flag, reference sample filtering method, reference sample filter tap, reference sample filter coefficient, prediction block filtering method, prediction block filter tap, prediction block filter coefficient, prediction block boundary filtering method, prediction block boundary filter tap, prediction block boundary filter coefficient, inter prediction mode, motion information, motion vector difference, reference picture index, etc., prediction block boundary filter coefficient, inter prediction mode, motion information, motion vector difference, reference picture index, motion vector, and/or motion vector, Inter prediction direction, inter prediction indicator, prediction list utilization flag, reference picture list, reference picture, POC, motion vector predictor, motion vector prediction index, motion vector prediction candidate, motion vector candidate list, information indicating whether merge mode is used, merge index, merge candidate list, information indicating whether skip mode is used, type of interpolation filter, tap of interpolation filter, filter coefficient of interpolation filter, size of motion vector, accuracy of motion vector representation, transform type, transform size, information indicating whether first transform is used, information indicating whether additional (second) transform is used, first transform selection information (or first transform index), second transform selection information (or second transform index), information indicating presence or absence of residual signal, motion vector prediction index, and motion vector prediction index, A coding block pattern, a coding block flag, a quantization parameter, a residual quantization parameter, a quantization matrix, information on an in-loop filter, information indicating whether an in-loop filter is applied, a coefficient of an in-loop filter, a tap of an in-loop filter, a shape/form of an in-loop filter, information indicating whether a deblocking filter is applied, a coefficient of a deblocking filter, a tap of a deblocking filter, a deblocking filter strength, a shape/form of a deblocking filter, information indicating whether an adaptive sample offset is applied, a value of an adaptive sample offset, a class of an adaptive sample offset, a type of an adaptive sample offset, information indicating whether an adaptive loop filter is applied, a coefficient of an adaptive loop filter, a tap of an adaptive loop filter, a shape/form of an adaptive loop filter, a binarization/inverse binarization method, a computer program, and a computer-readable storage medium, Context model, context model deciding method, context model updating method, information indicating whether normal mode is executed or not, information indicating whether bypass (bypass) mode is executed or not, significant coefficient flag, last significant coefficient flag, coding flag of coefficient group, position of last significant coefficient, information indicating whether value of coefficient is greater than 1, information indicating whether value of coefficient is greater than 2, information indicating whether value of coefficient is greater than 3, residual coefficient value information, sign information, reconstructed luma sample, re-quantized chroma sample, context binary, bypass binary, residual luma sample, residual chroma sample, transform coefficient, luma transform coefficient, chroma transform coefficient, quantized level, luma quantized level, chroma quantized level, transform coefficient level scanning method, size of motion vector search area on decoding apparatus side, and method of decoding apparatus, A shape/form of a motion vector search region on a decoding apparatus side, a number of motion vector searches on the decoding apparatus side, a size of a CTU, a minimum block size, a maximum block depth, a minimum block depth, an image display/output order, slice identification information, a slice type, slice partition information, parallel block group identification information, a parallel block group type, parallel block group partition information, parallel block identification information, a parallel block type, parallel block partition information, a picture type, a bit depth, an input sample bit depth, a reconstructed sample bit depth, a residual sample bit depth, a transform coefficient bit depth, a quantized level bit depth, information on a luminance signal, information on a chrominance signal, a color space of a target block, and a color space of a residual block. In addition, the above-described encoding parameter-related information may also be included in the encoding parameter. Information for calculating and/or deriving the above-described encoding parameters may also be included in the encoding parameters. Information calculated or derived using the above-described encoding parameters may also be included in the encoding parameters.

The prediction scheme may represent one of an intra prediction mode and an inter prediction mode.

The first transform selection information may indicate a first transform applied to the target block.

The second transform selection information may indicate a second transform applied to the target block.

The residual signal may represent the difference between the original signal and the predicted signal. Alternatively, the residual signal may be a signal generated by transforming a difference between the original signal and the prediction signal. Alternatively, the residual signal may be a signal generated by transforming and quantizing the difference between the original signal and the prediction signal. The residual block may be a residual signal for the block.

Here, signaling the information may indicate that the encoding apparatus 100 includes entropy-encoded information generated by performing entropy encoding on the flag or the index in the bitstream, and may indicate that the decoding apparatus 200 acquires the information by performing entropy decoding on the entropy-encoded information extracted from the bitstream. Here, the information may include a flag, an index, and the like.

The signal may represent information to be signaled. Hereinafter, information on the image and the block may be referred to as a "signal". Also, hereinafter, the terms "information" and "signal" may be used to have the same meaning and may be used interchangeably with each other. For example, the specific signal may be a signal representing a specific block. The original signal may be a signal representing the target block. The prediction signal may be a signal representing a prediction block. The residual signal may be a signal representing a residual block.

The bitstream may include information based on a specific syntax. The encoding apparatus 100 may generate a bitstream including information according to a specific syntax. The decoding apparatus 200 may acquire information from the bitstream according to a specific syntax.

Since the encoding apparatus 100 performs encoding via inter prediction, the encoded target image can be used as a reference image for another image to be subsequently processed. Accordingly, the encoding apparatus 100 may reconstruct or decode the encoded target image and store the reconstructed or decoded image as a reference image in the reference picture buffer 190. For decoding, inverse quantization and inverse transformation of the encoded target image may be performed.

The quantized levels may be inverse quantized by the inverse quantization unit 160 and inverse transformed by the inverse transformation unit 170. The inverse quantization unit 160 may generate inverse quantized coefficients by performing an inverse transform on the quantized levels. The inverse transform unit 170 may generate the inverse quantized and inverse transformed coefficients by performing an inverse transform on the inverse quantized coefficients.

The inverse quantized and inverse transformed coefficients may be added to the prediction block by adder 175. The inverse quantized and inverse transformed coefficients and the prediction block are added, and then a reconstructed block may be generated. Here, the inverse quantized and/or inverse transformed coefficients may represent coefficients on which one or more of inverse quantization and inverse transformation are performed, and may also represent a reconstructed residual block. Here, the reconstructed block may represent a restored block or a decoded block.

The reconstructed block may be filtered by the filter unit 180. Filter unit 180 may apply one or more of a deblocking filter, a Sample Adaptive Offset (SAO) filter, an Adaptive Loop Filter (ALF), and a non-local filter (NLF) to the reconstructed samples, reconstructed blocks, or reconstructed pictures. The filter unit 180 may also be referred to as a "loop filter".

The deblocking filter may remove block distortion occurring at the boundary between blocks. In order to determine whether to apply the deblocking filter, it may be decided to be included in the block and include the number of columns or lines of pixels on which to determine whether to apply the deblocking filter to the target block.

When the deblocking filter is applied to the target block, the applied filter may be different according to the strength of the deblocking filtering required. In other words, among different filters, a filter decided in consideration of the strength of the deblocking filtering may be applied to the target block. When the deblocking filter is applied to the target block, a filter corresponding to any one of the strong filter and the weak filter may be applied to the target block according to the strength of the required deblocking filter.

Further, when vertical filtering and horizontal filtering are performed on the target block, the horizontal filtering and the vertical filtering may be performed in parallel.

The SAO may add appropriate offsets to the pixel values to compensate for the coding error. The SAO may perform a correction on the image to which the deblocking is applied on a pixel basis, wherein the correction uses an offset of a difference between the original image and the image to which the deblocking is applied. In order to perform offset correction for an image, a method for dividing pixels included in the image into a certain number of regions, determining a region to which an offset is to be applied among the divided regions, and applying the offset to the determined region may be used, and a method for applying the offset in consideration of edge information of each pixel may also be used.

ALF may perform filtering based on values obtained by comparing a reconstructed image with an original image. After pixels included in an image have been divided into a predetermined number of groups, a filter to be applied to each group may be determined, and filtering may be performed differently for the respective groups. Information about whether to apply the adaptive loop filter may be signaled for each CU. Such information may be signaled for a luminance signal. The shape and filter coefficients of the ALF to be applied to each block may be different for each block. Alternatively, ALF having a fixed form may be applied to a block regardless of the characteristics of the block.

The non-local filter may perform filtering based on a reconstructed block similar to the target block. A region similar to the target block may be selected from the reconstructed picture, and filtering of the target block may be performed using statistical properties of the selected similar region. Information about whether to apply a non-local filter may be signaled for a Coding Unit (CU). Further, the shape and filter coefficients of the non-local filter to be applied to a block may be different according to the block.

The reconstructed block or the reconstructed image filtered by the filter unit 180 may be stored as a reference picture in the reference picture buffer 190. The reconstructed block filtered by the filter unit 180 may be a portion of a reference picture. In other words, the reference picture may be a reconstructed picture composed of the reconstructed block filtered by the filter unit 180. The stored reference pictures can then be used for inter prediction or motion compensation.

Fig. 2 is a block diagram showing a configuration of an embodiment of a decoding apparatus to which the present disclosure is applied.

The decoding apparatus 200 may be a decoder, a video decoding apparatus, or an image decoding apparatus.

Referring to fig. 2, the decoding apparatus 200 may include an entropy decoding unit 210, an inverse quantization (inverse quantization) unit 220, an inverse transformation unit 230, an intra prediction unit 240, an inter prediction unit 250, a switch 245, an adder 255, a filter unit 260, and a reference picture buffer 270.

The decoding apparatus 200 may receive the bitstream output from the encoding apparatus 100. The decoding apparatus 200 may receive a bit stream stored in a computer-readable storage medium and may receive a bit stream transmitted through a wired/wireless transmission medium stream.

The decoding apparatus 200 may perform decoding on the bitstream in an intra mode and/or an inter mode. Further, the decoding apparatus 200 may generate a reconstructed image or a decoded image through decoding, and may output the reconstructed image or the decoded image.

For example, an operation of switching to an intra mode or an inter mode based on a prediction mode for decoding may be performed by the switch 245. When the prediction mode for decoding is intra mode, switch 245 may be operated to switch to intra mode. When the prediction mode for decoding is an inter mode, switch 245 may be operated to switch to the inter mode.

The decoding apparatus 200 may acquire a reconstructed residual block by decoding an input bitstream and may generate a prediction block. When the reconstructed residual block and the prediction block are acquired, the decoding apparatus 200 may generate a reconstructed block, which is a target to be decoded, by adding the reconstructed residual block to the prediction block.

The entropy decoding unit 210 may generate symbols by performing entropy decoding on the bitstream based on the probability distribution of the bitstream. The generated symbols may comprise symbols in the form of quantized transform coefficient levels (i.e. quantized levels or quantized coefficients). Here, the entropy decoding method may be similar to the entropy encoding method described above. That is, the entropy decoding method may be the inverse process of the entropy encoding method described above.

The entropy decoding unit 210 may change coefficients having a one-dimensional (1D) vector form into a 2D block shape by a transform coefficient scanning method in order to decode quantized transform coefficient levels.

For example, the coefficients of a block may be changed to a 2D block shape by scanning the block coefficients using an upper right diagonal scan. Alternatively, which one of the upper right diagonal scan, the vertical scan, and the horizontal scan is to be used may be determined according to the size of the corresponding block and/or the intra prediction mode.

The quantized coefficients may be inverse quantized by the inverse quantization unit 220. The inverse quantization unit 220 may generate inverse quantized coefficients by performing inverse quantization on the quantized coefficients. Also, the inverse quantized coefficients may be inverse transformed by the inverse transform unit 230. The inverse transform unit 230 may generate a reconstructed residual block by performing an inverse transform on the inversely quantized coefficients. As a result of inverse quantization and inverse transformation performed on the quantized coefficients, a reconstructed residual block may be generated. Here, when generating the reconstructed residual block, the inverse quantization unit 220 may apply a quantization matrix to the quantized coefficients.

When using the intra mode, the intra prediction unit 240 may generate a prediction block by performing spatial prediction on a target block, wherein the spatial prediction uses pixel values of previously decoded neighboring blocks adjacent to the target block.

The inter prediction unit 250 may include a motion compensation unit. Alternatively, the inter prediction unit 250 may be designated as a "motion compensation unit".

When the inter mode is used, the motion compensation unit 250 may generate a prediction block by performing motion compensation for the target block, wherein the motion compensation uses the reference image stored in the reference picture buffer 270 and the motion vector.

The motion compensation unit may apply an interpolation filter to a partial region of the reference image when the motion vector has a value other than an integer, and may generate the prediction block using the reference image to which the interpolation filter is applied. To perform motion compensation, the motion compensation unit may determine which one of a skip mode, a merge mode, an Advanced Motion Vector Prediction (AMVP) mode, and a current picture reference mode corresponds to a motion compensation method for a PU included in the CU based on the CU, and may perform motion compensation according to the determined mode.

The reconstructed residual block and the prediction block may be added to each other by the adder 255. The adder 255 may generate a reconstructed block by adding the reconstructed residual block and the predicted block.

The reconstructed block may be filtered by the filter unit 260. Filter unit 260 may apply at least one of a deblocking filter, SAO filter, ALF, and NLF to the reconstructed block or the reconstructed image. The reconstructed image may be a picture including the reconstructed block.

The filter unit may output a reconstructed image.

The reconstructed image and/or reconstructed block filtered by the filter unit 260 may be stored as a reference picture in the reference picture buffer 270. The reconstructed block filtered by the filter unit 260 may be a portion of a reference picture. In other words, the reference picture may be an image composed of the reconstructed block filtered by the filter unit 260. The stored reference pictures can then be used for inter prediction or motion compensation.

Fig. 3 is a diagram schematically showing a partition structure of an image when the image is encoded and decoded.

Fig. 3 may schematically illustrate an example in which a single cell is partitioned into a plurality of sub-cells.

In order to efficiently partition an image, a Coding Unit (CU) may be used in encoding and decoding. The term "unit" may be used to collectively specify 1) a block comprising image samples and 2) syntax elements. For example, "partition of a unit" may represent "partition of a block corresponding to the unit".

A CU can be used as a basic unit for image encoding/decoding. A CU can be used as a unit to which one mode selected from an intra mode and an inter mode is applied in image encoding/decoding. In other words, in image encoding/decoding, it may be determined which one of an intra mode and an inter mode is to be applied to each CU.

Also, a CU may be a basic unit that predicts, transforms, quantizes, inversely transforms, inversely quantizes, and encodes/decodes transform coefficients.

Referring to fig. 3, a picture 300 may be sequentially partitioned into units corresponding to maximum coding units (LCUs), and a partition structure may be determined for each LCU. Here, the LCU may be used to have the same meaning as a Coding Tree Unit (CTU).

Partitioning a unit may mean partitioning a block corresponding to the unit. The block partition information may include depth information regarding a depth of the unit. The depth information may indicate a number of times the unit is partitioned and/or a degree to which the unit is partitioned. A single unit may be hierarchically partitioned into a plurality of sub-units while the single unit has depth information based on a tree structure.

Each partitioned sub-unit may have depth information. The depth information may be information indicating a size of the CU. Depth information may be stored for each CU.

Each CU may have depth information. When a CU is partitioned, the depth of the CU generated from the partition may be increased by 1 from the depth of the partitioned CU.

The partition structure may represent the distribution of Coding Units (CUs) in the LCU 310 for efficient encoding of images. Such a distribution may be determined according to whether a single CU is to be partitioned into multiple CUs. The number of CUs generated by partitioning may be a positive integer of 2 or more, including 2, 3, 4, 8, 16, etc.

According to the number of CUs generated by performing partitioning, the horizontal size and the vertical size of each CU generated by performing partitioning may be smaller than those of the CUs before being partitioned. For example, the horizontal and vertical dimensions of each CU generated by partitioning may be half the horizontal and vertical dimensions of the CU before partitioning.

Each partitioned CU may be recursively partitioned into four CUs in the same manner. At least one of a horizontal size and a vertical size of each partitioned CU may be reduced via recursive partitioning compared to at least one of a horizontal size and a vertical size of a CU before being partitioned.

Partitioning of CUs may be performed recursively until a predefined depth or a predefined size.

For example, the depth of a CU may have a value ranging from 0 to 3. The size of a CU may range from a size of 64 × 64 to a size of 8 × 8, depending on the depth of the CU.

For example, the depth of the LCU 310 may be 0 and the depth of the minimum coding unit (SCU) may be a predefined maximum depth. Here, as described above, the LCU may be a CU having a maximum coding unit size, and the SCU may be a CU having a minimum coding unit size.

Partitioning may begin at LCU 310, and the depth of a CU may increase by 1 each time the horizontal and/or vertical dimensions of the CU are reduced by partitioning.

For example, for each depth, a CU that is not partitioned may have a size of 2N × 2N. Further, in the case where CUs are partitioned, CUs of a size of 2N × 2N may be partitioned into four CUs each of a size of N × N. The value of N may be halved each time the depth is increased by 1.

Referring to fig. 3, an LCU having a depth of 0 may have 64 × 64 pixels or 64 × 64 blocks. 0 may be a minimum depth. An SCU of depth 3 may have 8 × 8 pixels or 8 × 8 blocks. 3 may be the maximum depth. Here, a CU having 64 × 64 blocks as an LCU may be represented by depth 0. A CU with 32 x 32 blocks may be represented with depth 1. A CU with 16 x 16 blocks may be represented with depth 2. A CU with 8 x 8 blocks as SCU can be represented by depth 3.

The information on whether the corresponding CU is partitioned may be represented by partition information of the CU. The partition information may be 1-bit information. All CUs except the SCU may include partition information. For example, the value of the partition information of the CU that is not partitioned may be the first value. The value of the partition information of the partitioned CU may be the second value. When the partition information indicates whether the CU is partitioned, the first value may be "0" and the second value may be "1".

For example, when a single CU is partitioned into four CUs, the horizontal and vertical sizes of each of the four CUs generated by partitioning may be half the horizontal and vertical sizes of the CU before being partitioned. When a CU having a size of 32 × 32 is partitioned into four CUs, the size of each of the partitioned four CUs may be 16 × 16. When a single CU is partitioned into four CUs, the CUs may be considered to have been partitioned in a quadtree structure. In other words, the quadtree partition may be considered to have been applied to the CU.

For example, when a single CU is partitioned into two CUs, the horizontal size or the vertical size of each of the two CUs generated by partitioning may be half the horizontal size or the vertical size of the CU before being partitioned. When a CU having a size of 32 × 32 is vertically partitioned into two CUs, the size of each of the partitioned two CUs may be 16 × 32. When a CU having a size of 32 × 32 is horizontally partitioned into two CUs, the size of each of the partitioned two CUs may be 32 × 16. When a single CU is partitioned into two CUs, the CUs may be considered to have been partitioned in a binary tree structure. In other words, the binary tree partition may be considered to have been applied to the CU.

For example, when a single CU is partitioned (or divided) into three CUs, the original CU before being partitioned is partitioned such that its horizontal or vertical size is 1: 2: the ratio of 1 is divided, thus enabling generation of three sub-CUs. For example, when a CU of size 16 × 32 is horizontally partitioned into three sub-CUs, the three sub-CUs generated by the partitioning may have sizes of 16 × 8, 16 × 16, and 16 × 8, respectively, in the direction from top to bottom. For example, when a CU of size 32 × 32 is vertically partitioned into three sub-CUs, the three sub-CUs generated by the partitioning may have sizes of 8 × 32, 16 × 32, and 8 × 32, respectively, in the left-to-right direction. When a single CU is partitioned into three CUs, the CUs may be considered to be partitioned in a ternary tree. In other words, a ternary tree partition may be considered to have been applied to a CU.

Both quad tree and binary tree partitioning are applied to LCU310 of fig. 3.

In the encoding apparatus 100, a Coding Tree Unit (CTU) having a size of 64 × 64 may be partitioned into a plurality of smaller CUs by a recursive quad-tree structure. A single CU may be partitioned into four CUs having the same size. Each CU may be recursively partitioned and may have a quadtree structure.

By recursive partitioning of CUs, the optimal partitioning method that results in the smallest rate-distortion cost can be selected.

The Coding Tree Unit (CTU)320 in fig. 3 is an example of a CTU to which a quad tree partition, a binary tree partition, and a ternary tree partition are all applied.

As described above, in order to partition the CTU, at least one of the quadtree partition, the binary tree partition, and the ternary tree partition may be applied to the CTU. Partitions may be applied based on a particular priority.

For example, quadtree partitioning may be preferentially applied to CTUs. CUs that cannot be further partitioned in a quadtree fashion may correspond to leaf nodes of the quadtree. CUs corresponding to leaf nodes of a quadtree may be root nodes of a binary tree and/or a ternary tree. That is, CUs corresponding to leaf nodes of a quadtree may be partitioned in binary or ternary tree form, or may not be further partitioned. In this case, each CU generated by applying binary tree partitioning or ternary tree partitioning to CUs corresponding to leaf nodes of the quadtree is prevented from being partitioned again by the quadtree, thereby efficiently performing partitioning of blocks and/or signaling of block partition information.

The partition of the CU corresponding to each node of the quadtree may be signaled using the four-partition information. The four-partition information having a first value (e.g., "1") may indicate that the corresponding CU is partitioned in a quadtree form. The four-partition information having a second value (e.g., "0") may indicate that the corresponding CU is not partitioned in a quadtree form. The quad-partition information may be a flag having a specific length (e.g., 1 bit).

There may not be a priority between the binary tree partition and the ternary tree partition. That is, CUs corresponding to leaf nodes of a quadtree may be partitioned in a binary tree form or a ternary tree form. Furthermore, CUs generated by binary tree partitioning or ternary tree partitioning may or may not be further partitioned in binary tree form or ternary tree form.

Partitions that are executed when there is no priority between a binary tree partition and a ternary tree partition may be referred to as "multi-type tree partitions". That is, a CU corresponding to a leaf node of a quadtree may be a root node of a multi-type tree. The partition of the CU corresponding to each node of the multi-type tree may be signaled using at least one of information indicating whether the CU is partitioned by the multi-type tree, partition direction information, and partition tree information. For the partition of the CU corresponding to each node of the multi-type tree, information indicating whether or not the partition by the multi-type tree is performed, partition direction information, and partition tree information may be sequentially signaled.

For example, the information indicating whether a CU is partitioned in a multi-type tree and has a first value (e.g., "1") may indicate that the corresponding CU is partitioned in a multi-type tree form. The information indicating whether the CU is partitioned by the multi-type tree and has a second value (e.g., "0") may indicate that the corresponding CU is not partitioned in the multi-type tree form.

When a CU corresponding to each node of the multi-type tree is partitioned in the multi-type tree form, the corresponding CU may further include partition direction information.

The partition direction information may indicate a partition direction of the multi-type tree partition. The partition direction information having a first value (e.g., "1") may indicate that the corresponding CU is partitioned in the vertical direction. The partition direction information having the second value (e.g., "0") may indicate that the corresponding CU is partitioned in the horizontal direction.

When a CU corresponding to each node of the multi-type tree is partitioned in the multi-type tree form, the corresponding CU may further include partition tree information. The partition tree information may indicate a tree that is used for multi-type tree partitioning.

For example, partition tree information having a first value (e.g., "1") may indicate that the corresponding CU is partitioned in binary tree form. The partition tree information having the second value (e.g., "0") may indicate that the corresponding CU is partitioned in a ternary tree form.

Here, each of the above-described information indicating whether partitioning by the multi-type tree is performed, the partition tree information, and the partition direction information may be a flag having a specific length (e.g., 1 bit).

At least one of the above-described four partition information, information indicating whether or not partitioning is performed per multi-type tree, partition direction information, and partition tree information may be entropy-encoded and/or entropy-decoded. To perform entropy encoding/decoding of such information, information of neighboring CUs adjacent to the target CU may be used.

For example, it may be considered that there is a high probability that the partition form (i.e., partition/non-partition, partition tree, and/or partition direction) of the left-side CU and/or the upper CU and the partition form of the target CU may be similar to each other. Thus, based on the information of neighboring CUs, context information for entropy encoding and/or entropy decoding of the information of the target CU may be derived. Here, the information of the neighboring CU may include at least one of: 1) four partition information of neighboring CUs, 2) information indicating whether the neighboring CUs are partitioned by a multi-type tree, 3) partition direction information of the neighboring CUs, and 4) partition tree information of the neighboring CUs.

In another embodiment of binary tree partitioning and ternary tree partitioning, binary tree partitioning may be performed preferentially. That is, binary tree partitioning may be applied first, and then CUs corresponding to leaf nodes of the binary tree may be set as root nodes of the ternary tree. In this case, the quadtree partitioning or the binary tree partitioning may not be performed on CUs corresponding to the nodes of the ternary tree.

CUs that are not further partitioned by quadtree partitioning, binary tree partitioning, and/or ternary tree partitioning may be units of coding, prediction, and/or transformation. That is, a CU may not be further partitioned for prediction and/or transform. Accordingly, a partition structure for partitioning a CU into Prediction Units (PUs)/or Transform Units (TUs), partition information thereof, and the like may not exist in a bitstream.

However, when the size of a CU, which is a unit of partitioning, is larger than the size of the largest transform block, the CU may be recursively partitioned until the size of the CU becomes smaller than or equal to the size of the largest transform block. For example, when the size of a CU is 64 × 64 and the size of the largest transform block is 32 × 32, the CU may be partitioned into four 32 × 32 blocks in order to perform the transform. For example, when the size of a CU is 32 × 64 and the size of the largest transform block is 32 × 32, the CU may be partitioned into two 32 × 32 blocks.

In this case, the information indicating whether a CU is partitioned for transformation may not be separately signaled. Without signaling, it may be determined whether a CU is partitioned via a comparison between the horizontal size (and/or vertical size) of the CU and the horizontal size (and/or vertical size) of the largest transform block. For example, a CU may be vertically halved when the horizontal size of the CU is larger than the horizontal size of the largest transform block. Furthermore, when the vertical size of a CU is larger than the vertical size of the largest transform block, the CU may be horizontally halved.

The information on the maximum size and/or the minimum size of the CU and the information on the maximum size and/or the minimum size of the transform block may be signaled or determined at a level higher than the level of the CU. For example, the higher level may be a sequence level, a picture level, a parallel block group level, or a stripe level. For example, the minimum size of a CU may be set to 4 × 4. For example, the maximum size of the transform block may be set to 64 × 64. For example, the maximum size of the transform block may be set to 4 × 4.

Information about a minimum size of a CU corresponding to a leaf node of the quadtree (i.e., the minimum size of the quadtree) and/or information about a maximum depth of a path from a root node of the multi-type tree to the leaf node (i.e., the maximum depth of the multi-type tree) may be signaled or determined at a level higher than that of the CU. For example, the higher level may be a sequence level, a picture level, a stripe level, a parallel block group level, or a parallel block level. Information regarding a minimum size of the quadtree and/or information regarding a maximum depth of the multi-type tree may be separately signaled or determined at each of the intra-stripe level and the inter-stripe level.

Information about the difference between the size of the CTU and the maximum size of the transform block may be signaled or determined at a level higher than the level of the CU. For example, the higher level may be a sequence level, a picture level, a slice level, a parallel block group level, or a parallel block level. Information about the maximum size of the CU corresponding to each node of the binary tree (i.e., the maximum size of the binary tree) may be determined based on the size of the CTU and the information of the difference. The maximum size of the CU corresponding to each node of the ternary tree (i.e., the maximum size of the ternary tree) may have different values according to the type of the strip. For example, the maximum size of the ternary tree at the intra-stripe level may be 32 × 32. For example, the maximum size of the tri-ary tree at the inter-band level may be 128 × 128. For example, the minimum size of the CU corresponding to each node of the binary tree (i.e., the minimum size of the binary tree) and/or the minimum size of the CU corresponding to each node of the ternary tree (i.e., the minimum size of the ternary tree) may be set to the minimum size of the CU.

In another example, the maximum size of the binary tree and/or the maximum size of the ternary tree may be signaled or determined at the slice level. Further, a minimum size of the binary tree and/or a minimum size of the ternary tree may be signaled or determined at the slice level.

Information indicating whether partitioning by the multi-type tree is performed, partition tree information, and/or partition direction information may or may not exist in the bitstream based on the various block sizes and depths, the four-partition information, as described above.

For example, when the size of the CU is not greater than the minimum size of the quadtree, the CU may not include the four-partition information, and the four-partition information of the CU may be inferred to be a second value.

For example, when the size (horizontal size and vertical size) of a CU corresponding to each node of the multi-type tree is larger than the maximum size (horizontal size and vertical size) of the binary tree and/or the maximum size (horizontal size and vertical size) of the ternary tree, the CU may not be partitioned in the binary tree form and/or the ternary tree form. By this determination, information indicating whether partitioning is performed per multi-type tree may not be signaled, but may be inferred as a second value.

Alternatively, a CU may not be partitioned in binary tree form and/or ternary tree form when the size (horizontal size and vertical size) of the CU corresponding to each node of the multi-type tree is equal to the minimum size (horizontal size and vertical size) of the binary tree, or when the size (horizontal size and vertical size) of the CU is equal to twice the minimum size (horizontal size and vertical size) of the ternary tree. By this determination, information indicating whether partitioning is performed per multi-type tree may be signaled but may be inferred as a second value. The reason for this is that when a CU is partitioned in binary tree form and/or ternary tree form, a CU smaller than the minimum size of the binary tree and/or the minimum size of the ternary tree is generated.

Alternatively, the binary tree partition or the ternary tree partition may be restricted based on the size of the virtual pipeline data unit (i.e., the size of the pipeline buffer). For example, binary or ternary tree partitioning may be limited when a CU is partitioned into sub-CUs that do not fit the size of the pipeline buffer by binary or ternary tree partitioning. The size of the pipeline buffer may be equal to the maximum size of the transform block (e.g., 64 x 64).

For example, when the size of the pipeline buffer is 64 × 64, the following partitions may be restricted.

Ternary tree partitioning for nxm CU (where N and/or M are 128)

Horizontal binary tree partitioning for 128 × N CUs (where N < ═ 64)

Vertical binary tree partitioning for nx128 CU (where N < ═ 64)

Alternatively, a CU may not be partitioned in binary and/or ternary tree form when the depth of the CU corresponding to each node of the multi-type tree is equal to the maximum depth of the multi-type tree. By this determination, information indicating whether partitioning is performed per multi-type tree may be signaled but may be inferred as a second value.

Alternatively, the information indicating whether partitioning per multi-type tree is performed may be signaled only when at least one of the vertical binary tree partition, the horizontal binary tree partition, the vertical ternary tree partition, and the horizontal ternary tree partition is possible for a CU corresponding to each node of the multi-type tree. Otherwise, the CU may not be partitioned in binary tree form and/or ternary tree form. By this determination, information indicating whether partitioning is performed per multi-type tree may not be signaled, but may be inferred as a second value.

Alternatively, for a CU corresponding to each node of the multi-type tree, the partition direction information may be signaled only when both vertical and horizontal binary tree partitions are feasible or only when both vertical and horizontal ternary tree partitions are feasible. Otherwise, partition direction information may be not signaled, but may be inferred as a value indicating the direction in which the CU may be partitioned.

Alternatively, for a CU corresponding to each node of the multi-type tree, partition tree information may be signaled only when both vertical binary tree partitioning and vertical ternary tree partitioning are feasible, or only when both horizontal binary tree partitioning and horizontal ternary tree partitioning are feasible. Otherwise, partition tree information may be not signaled, but may be inferred as a value indicating a tree applicable to the partitions of the CU.

Fig. 4 is a diagram illustrating a form of a prediction unit that a coding unit can include.

Among CUs partitioned from the LCU, CUs that are no longer partitioned may be divided into one or more Prediction Units (PUs). This division is also referred to as "partitioning".

A PU may be the basic unit for prediction. The PU may be encoded and decoded in any one of a skip mode, an inter mode, and an intra mode. The PU may be partitioned into various shapes according to various modes. For example, the target block described above with reference to fig. 1 and the target block described above with reference to fig. 2 may both be PUs.

A CU may not be partitioned into PUs. When a CU is not divided into PUs, the size of the CU and the size of the PU may be equal to each other.

In skip mode, there may be no partition in a CU. In the skip mode, the 2N × 2N mode 410 may be supported without partitioning, wherein the size of the PU and the size of the CU are the same as each other in the 2N × 2N mode 410.

In inter mode, there may be 8 types of partition shapes in a CU. For example, in the inter mode, a 2N × 2N mode 410, a 2N × N mode 415, an N × 2N mode 420, an N × N mode 425, a 2N × nU mode 430, a 2N × nD mode 435, an nL × 2N mode 440, and an nR × 2N mode 445 may be supported.

In intra mode, a 2N × 2N mode 410 and an N × N mode 425 may be supported.

In the 2N × 2N mode 410, PUs of size 2N × 2N may be encoded. A PU of size 2N × 2N may represent a PU of the same size as the CU. For example, a PU of size 2N × 2N may have a size 64 × 64, 32 × 32, 16 × 16, or 8 × 8.

In the nxn mode 425, PUs of size nxn may be encoded.

For example, in intra prediction, when the size of a PU is 8 × 8, four partitioned PUs may be encoded. The size of each partitioned PU may be 4 x 4.

When a PU is encoded in intra mode, the PU may be encoded using any one of a plurality of intra prediction modes. For example, High Efficiency Video Coding (HEVC) techniques may provide 35 intra prediction modes, a PU may be encoded in any one of the 35 intra prediction modes.

Which of the 2 nx 2N mode 410 and the nxn mode 425 is to be used to encode the PU may be determined based on a rate-distortion cost.

The encoding apparatus 100 may perform an encoding operation on PUs having a size of 2N × 2N. Here, the encoding operation may be an operation of encoding the PU in each of a plurality of intra prediction modes that can be used by the encoding apparatus 100. Through the encoding operation, the optimal intra prediction mode for a PU of size 2N × 2N may be derived. The optimal intra prediction mode may be an intra prediction mode in which a minimum rate-distortion cost occurs when a PU having a size of 2N × 2N is encoded, among a plurality of intra prediction modes that can be used by the encoding apparatus 100.

Further, the encoding apparatus 100 may sequentially perform an encoding operation on the respective PUs obtained by performing the N × N partitioning. Here, the encoding operation may be an operation of encoding the PU in each of a plurality of intra prediction modes that can be used by the encoding apparatus 100. Through the encoding operation, the optimal intra prediction mode for a PU of size N × N may be derived. The optimal intra prediction mode may be an intra prediction mode in which a minimum rate-distortion cost occurs when a PU having a size of N × N is encoded, among a plurality of intra prediction modes that can be used by the encoding apparatus 100.

The encoding apparatus 100 may determine which one of a PU of size 2N × 2N and a PU of size N × N is to be encoded based on a comparison between rate-distortion costs of PUs of size 2N × 2N and rate-distortion costs of PUs of size N × N.

A single CU may be partitioned into one or more PUs, and a PU may be partitioned into multiple PUs.

For example, when a single PU is partitioned into four PUs, the horizontal and vertical dimensions of each of the four PUs generated by the partitioning may be half the horizontal and vertical dimensions of the PU before being partitioned. When a PU of size 32 x 32 is partitioned into four PUs, the size of each of the four partitioned PUs may be 16 x 16. When a single PU is partitioned into four PUs, the PUs may be considered to have been partitioned in a quad-tree structure.

For example, when a single PU is partitioned into two PUs, the horizontal or vertical size of each of the two PUs generated by the partitioning may be half the horizontal or vertical size of the PU before being partitioned. When a PU of size 32 x 32 is vertically partitioned into two PUs, the size of each of the two partitioned PUs may be 16 x 32. When a PU of size 32 x 32 is horizontally partitioned into two PUs, the size of each of the two partitioned PUs may be 32 x 16. When a single PU is partitioned into two PUs, the PUs may be considered to have been partitioned in a binary tree structure.

Fig. 5 is a diagram illustrating a form of a transform unit that can be included in a coding unit.

A Transform Unit (TU) may be a basic unit used in a CU for processes such as transform, quantization, inverse transform, inverse quantization, entropy coding, and entropy decoding.

The TU may have a square shape or a rectangular shape. The shape of a TU may be determined based on the size and/or shape of the CU.

Among CUs partitioned from an LCU, CUs that are no longer partitioned as CUs may be partitioned into one or more TUs. Here, the partition structure of the TU may be a quad-tree structure. For example, as shown in fig. 5, a single CU 510 may be partitioned one or more times according to a quadtree structure. With such partitioning, a single CU 510 may be composed of TUs having various sizes.

A CU may be considered to be recursively divided when a single CU is divided two or more times. By the division, a single CU may be composed of Transform Units (TUs) having various sizes.

Alternatively, a single CU may be divided into one or more TUs based on the number of vertical and/or horizontal lines dividing the CU.

A CU may be divided into symmetric TUs or asymmetric TUs. For the division into asymmetric TUs, information regarding the size and/or shape of each TU may be signaled from the encoding apparatus 100 to the decoding apparatus 200. Alternatively, the size and/or shape of each TU may be derived from information on the size and/or shape of the CU.

A CU may not be divided into TUs. When a CU is not divided into TUs, the size of the CU and the size of the TU may be equal to each other.

A single CU may be partitioned into one or more TUs, and a TU may be partitioned into multiple TUs.

For example, when a single TU is partitioned into four TUs, the horizontal size and the vertical size of each of the four TUs generated by the partitioning may be half of those of the TU before being partitioned. When a TU having a size of 32 × 32 is partitioned into four TUs, the size of each of the four partitioned TUs may be 16 × 16. When a single TU is partitioned into four TUs, the TUs may be considered to have been partitioned in a quadtree structure.

For example, when a single TU is partitioned into two TUs, the horizontal size or the vertical size of each of the two TUs generated by the partitioning may be half of the horizontal size or the vertical size of the TU before being partitioned. When a TU of a size of 32 × 32 is vertically partitioned into two TUs, each of the two partitioned TUs may be of a size of 16 × 32. When a TU having a size of 32 × 32 is horizontally partitioned into two TUs, the size of each of the two partitioned TUs may be 32 × 16. When a single TU is partitioned into two TUs, the TUs may be considered to have been partitioned in a binary tree structure.

A CU may be partitioned in a different manner than shown in fig. 5.

For example, a single CU may be divided into three CUs. The horizontal sizes or vertical sizes of the three CUs generated by the division may be 1/4, 1/2, and 1/4 of the horizontal size or vertical size of the original CU before being divided, respectively.

For example, when a CU having a size of 32 × 32 is vertically divided into three CUs, the sizes of the three CUs generated by the division may be 8 × 32, 16 × 32, and 8 × 32, respectively. In this way, when a single CU is divided into three CUs, the CU can be considered to be divided in a form of a ternary tree.

One of exemplary division forms (i.e., quadtree division, binary tree division, and ternary tree division) may be applied to the division of the CU, and a variety of division schemes may be combined and used together for the division of the CU. Here, a case where a plurality of division schemes are combined and used together may be referred to as "composite tree-like division".

Fig. 6 illustrates partitioning of blocks according to an example.

In the video encoding and/or decoding process, as shown in fig. 6, the target block may be divided. For example, the target block may be a CU.

For the division of the target block, an indicator indicating division information may be signaled from the encoding apparatus 100 to the decoding apparatus 200. The partition information may be information indicating how the target block is partitioned.

The partition information may be one or more of a partition flag (hereinafter, referred to as "split _ flag"), a quad-binary flag (hereinafter, referred to as "QB _ flag"), a quad-tree flag (hereinafter, referred to as "quadtree _ flag"), a binary tree flag (hereinafter, referred to as "binytree _ flag"), and a binary type flag (hereinafter, referred to as "Btype _ flag").

The "split _ flag" may be a flag indicating whether the block is divided. For example, a split _ flag value of 1 may indicate that the corresponding block is divided. A split _ flag value of 0 may indicate that the corresponding block is not divided.

"QB _ flag" may be a flag indicating which of the quad tree form and the binary tree form corresponds to the shape in which the block is divided. For example, a QB _ flag value of 0 may indicate that the block is divided in a quad tree form. A QB _ flag value of 1 may indicate that the block is divided in a binary tree form. Alternatively, the QB _ flag value of 0 may indicate that the block is divided in a binary tree form. A QB _ flag value of 1 may indicate that the block is divided in a quad tree form.

"quadtree _ flag" may be a flag indicating whether a block is divided in a quad-tree form. For example, a value of quadtree _ flag of 1 may indicate that the block is divided in a quad-tree form. A quadtree _ flag value of 0 may indicate that the block is not divided in a quadtree form.

"binarytree _ flag" may be a flag indicating whether a block is divided in a binary tree form. For example, a binarytree _ flag value of 1 may indicate that the block is divided in a binary tree form. A binarytree _ flag value of 0 may indicate that the block is not divided in a binary tree form.

"Btype _ flag" may be a flag indicating which one of the vertical division and the horizontal division corresponds to the division direction when the block is divided in the binary tree form. For example, a Btype _ flag value of 0 may indicate that the block is divided in the horizontal direction. A Btype _ flag value of 1 may indicate that the block is divided in the vertical direction. Alternatively, a Btype _ flag value of 0 may indicate that the block is divided in the vertical direction. A Btype _ flag value of 1 may indicate that the block is divided in the horizontal direction.

For example, the partition information of the block in fig. 6 may be derived by signaling at least one of quadtree _ flag, binytree _ flag, and Btype _ flag, as shown in table 1 below.

TABLE 1

For example, the partition information of the block in fig. 6 may be derived by signaling at least one of split _ flag, QB _ flag, and Btype _ flag, as shown in table 2 below.

TABLE 2

The partitioning method may be limited to only a quad tree or a binary tree depending on the size and/or shape of the block. When this restriction is applied, the split _ flag may be a flag indicating whether the block is divided in a quad tree form or a flag indicating whether the block is divided in a binary tree form. The size and shape of the block may be derived from the depth information of the block, and the depth information may be signaled from the encoding apparatus 100 to the decoding apparatus 200.

When the size of the block falls within a certain range, it is possible to perform division only in the form of a quad tree. For example, the specific range may be defined by at least one of a maximum block size and a minimum block size that can be divided only in a quad-tree form.

Information indicating the maximum block size and the minimum block size that can be divided only in the form of a quadtree may be signaled from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. Further, this information may be signaled for at least one of units such as video, sequences, pictures, parameters, parallel block groups, and stripes (or slices).

Alternatively, the maximum block size and/or the minimum block size may be a fixed size predefined by the encoding apparatus 100 and the decoding apparatus 200. For example, when the size of the block is larger than 64 × 64 and smaller than 256 × 256, only the division in the form of a quad tree is possible. In this case, split _ flag may be a flag indicating whether to perform partitioning in the form of a quad tree.

When the size of the block is larger than the maximum size of the transform block, only partitioning in the form of a quadtree is possible. Here, the sub-block generated by the partition may be at least one of a CU and a TU.

In this case, the split _ flag may be a flag indicating whether partitioning in the form of a quad-tree is performed.

When the size of the block falls within a specific range, division in only a binary tree form or a ternary tree form is possible. For example, the specific range may be defined by at least one of a maximum block size and a minimum block size that can be divided only in a binary tree form or a ternary tree form.

Information indicating the maximum block size and/or the minimum block size that can be divided only in a binary tree form or in a ternary tree form may be signaled from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. Further, this information may be signaled for at least one of the units such as sequence, picture, and slice (or slice).

Alternatively, the maximum block size and/or the minimum block size may be a fixed size predefined by the encoding apparatus 100 and the decoding apparatus 200. For example, when the size of the block is larger than 8 × 8 and smaller than 16 × 16, only division in a binary tree form is possible. In this case, split _ flag may be a flag indicating whether to perform partitioning in a binary tree form or a ternary tree form.

The above description of partitioning in a quadtree format can be equally applied to a binary tree format and/or a ternary tree format.

The partitioning of a block may be limited by previous partitions. For example, when a block is partitioned in a specific binary tree form and a plurality of sub-blocks are generated from the partition, each sub-block may be additionally partitioned only in a specific tree form. Here, the specific tree form may be at least one of a binary tree form, a ternary tree form, and a quaternary tree form.

The indicator may not be signaled when the horizontal size or the vertical size of the partition block is a size that cannot be further divided.

Fig. 7 is a diagram for explaining an embodiment of an intra prediction process.

The arrows extending radially from the center of the graph in fig. 7 indicate the prediction directions of the directional intra prediction modes. Further, numbers appearing near the arrows indicate examples of mode values assigned to the intra prediction mode or the prediction direction of the intra prediction mode.

In fig. 7, the number "0" may represent a planar mode as a non-directional intra prediction mode. The number "1" may represent a DC mode as a non-directional intra prediction mode.

Intra-coding and/or decoding may be performed using reference samples of neighboring units of the target block. The neighboring blocks may be reconstructed neighboring blocks. The reference samples may represent neighboring samples.

For example, intra encoding and/or decoding may be performed using values of reference samples included in the reconstructed neighboring blocks or encoding parameters of the reconstructed neighboring blocks.

The encoding apparatus 100 and/or the decoding apparatus 200 may generate the prediction block by performing intra prediction on the target block based on the information on the sampling point in the target image. When the intra prediction is performed, the encoding apparatus 100 and/or the decoding apparatus 200 may generate a prediction block for the target block by performing the intra prediction based on the information on the sampling points in the target image. When the intra prediction is performed, the encoding apparatus 100 and/or the decoding apparatus 200 may perform directional prediction and/or non-directional prediction based on the at least one reconstructed reference sample.

The prediction block may be a block generated as a result of performing intra prediction. The prediction block may correspond to at least one of a CU, a PU, and a TU.

The units of the prediction block may have a size corresponding to at least one of the CU, the PU, and the TU. The prediction block may have a square shape with a size of 2N × 2N or N × N. The size N × N may include sizes 4 × 4, 8 × 8, 16 × 16, 32 × 32, 64 × 64, and so on.

Alternatively, the prediction block may be a square block having a size of 2 × 2, 4 × 4, 8 × 8, 16 × 16, 32 × 32, 64 × 64, or the like or a rectangular block having a size of 2 × 8, 4 × 8, 2 × 16, 4 × 16, 8 × 16, or the like.

The intra prediction may be performed in consideration of an intra prediction mode for the target block. The number of intra prediction modes that the target block may have may be a predefined fixed value, and may be a value differently determined according to the properties of the prediction block. For example, the properties of the prediction block may include the size of the prediction block, the type of prediction block, and the like. Furthermore, the properties of the prediction block may indicate the coding parameters used for the prediction block.

For example, the number of intra prediction modes may be fixed to N regardless of the size of the prediction block. Alternatively, the number of intra prediction modes may be, for example, 3, 5, 9, 17, 34, 35, 36, 65, 67, or 95.

The intra prediction mode may be a non-directional mode or a directional mode.

For example, the intra prediction modes may include two non-directional modes and 65 directional modes corresponding to numbers 0 to 66 shown in fig. 7.

For example, in the case of using a specific intra prediction method, the intra prediction modes may include two non-directional modes corresponding to numbers-14 to 80 shown in fig. 7 and 93 directional modes.

The two non-directional modes may include a DC mode and a planar mode.

The directional mode may be a prediction mode having a specific direction or a specific angle. The directional mode may also be referred to as an "angular mode".

The intra prediction mode may be represented by at least one of a mode number, a mode value, a mode angle, and a mode direction. In other words, the terms "a (mode) number of an intra prediction mode", "a (mode) value of an intra prediction mode", "a (mode) angle of an intra prediction mode", and "a (mode) direction of an intra prediction mode" may be used to have the same meaning, and may be used interchangeably with each other.

The number of intra prediction modes may be M. The value of M may be 1 or greater. In other words, the number of intra prediction modes may be M, where M includes the number of non-directional modes and the number of directional modes.

The number of intra prediction modes may be fixed to M regardless of the size and/or color components of the block. For example, the number of intra prediction modes may be fixed to any one of 35 and 67 regardless of the size of the block.

Alternatively, the number of intra prediction modes may be different according to the shape, size, and/or type of color component of the block.

For example, in fig. 7, the directional prediction mode as shown by the dotted line may be applied only to prediction for non-square blocks.

For example, the larger the size of the block, the larger the number of intra prediction modes. Alternatively, the larger the size of the block, the smaller the number of intra prediction modes. When the size of the block is 4 × 4 or 8 × 8, the number of intra prediction modes may be 67. When the size of the block is 16 × 16, the number of intra prediction modes may be 35. When the size of the block is 32 × 32, the number of intra prediction modes may be 19. When the size of the block is 64 × 64, the number of intra prediction modes may be 7.

For example, the number of intra prediction modes may be different according to whether a color component is a luminance signal or a chrominance signal. Alternatively, the number of intra prediction modes corresponding to the luminance component block may be greater than the number of intra prediction modes corresponding to the chrominance component block.

For example, in the vertical mode having a mode value of 50, prediction may be performed in the vertical direction based on the pixel value of the reference sampling point. For example, in the horizontal mode with the mode value of 18, prediction may be performed in the horizontal direction based on the pixel value of the reference sampling point.

Even in a directional mode other than the above-described modes, the encoding apparatus 100 and the decoding apparatus 200 may perform intra prediction on a target unit using reference samples according to an angle corresponding to the directional mode.

The intra prediction mode located on the right side with respect to the vertical mode may be referred to as a "vertical-right mode". The intra prediction mode located below the horizontal mode may be referred to as a "horizontal-below mode". For example, in fig. 7, the intra prediction mode having one of the mode values 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, and 66 may be a vertical-right mode. The intra prediction mode having a mode value of one of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, and 17 may be a horizontal-lower mode.

The non-directional mode may include a DC mode and a planar mode. For example, the value of the DC mode may be 1. The value of the planar mode may be 0.

The directional pattern may include an angular pattern. Among the plurality of intra prediction modes, the remaining modes other than the DC mode and the planar mode may be directional modes.

When the intra prediction mode is the DC mode, the prediction block may be generated based on an average value of pixel values of the plurality of reference pixels. For example, the values of the pixels of the prediction block may be determined based on an average of pixel values of a plurality of reference pixels.

The number of intra prediction modes and the mode values of the respective intra prediction modes described above are merely exemplary. The number of intra prediction modes described above and the mode values of the respective intra prediction modes may be defined differently according to embodiments, implementations, and/or requirements.

In order to perform intra prediction on the target block, a step of checking whether or not a sample included in the reconstructed neighboring block can be used as a reference sample of the target block may be performed. When there are samples that cannot be used as reference samples of the target block among samples in the neighboring block, a value generated via interpolation and/or duplication using at least one sample value among samples included in the reconstructed neighboring block may replace sample values of samples that cannot be used as reference samples. When a value generated via replication and/or interpolation replaces a sample value of an existing sample, the sample may be used as a reference sample for the target block.

When intra prediction is used, a filter may be applied to at least one of the reference sampling point and the prediction sampling point based on at least one of an intra prediction mode and a size of the target block.

The type of the filter to be applied to at least one of the reference samples and the prediction samples may be different according to at least one of an intra prediction mode of the target block, a size of the target block, and a shape of the target block. The type of filter may be classified according to one or more of the length of the filter tap, the value of the filter coefficient, and the filter strength. The length of the filter taps may represent the number of filter taps. Further, the number of filter taps may represent the length of the filter.

When the intra prediction mode is the planar mode, the sample value of the prediction target block may be generated using a weighted sum of the upper reference sample of the target block, the left reference sample of the target block, the upper right reference sample of the target block, and the lower left reference sample of the target block according to the position of the prediction target sample in the prediction block when generating the prediction block of the target block.

When the intra prediction mode is the DC mode, an average value of the reference samples above the target block and the reference samples to the left of the target block may be used in generating the prediction block of the target block. Further, filtering using the value of the reference sampling point may be performed on a specific row or a specific column in the target block. The particular row may be one or more upper rows adjacent to the reference sample point. The particular column may be one or more left-hand columns adjacent to the reference sample point.

When the intra prediction mode is a directional mode, a prediction block may be generated using an upper reference sample, a left reference sample, an upper right reference sample, and/or a lower left reference sample of the target block.

To generate the predicted samples described above, real number based interpolation may be performed.

The intra prediction mode of the target block may be predicted from intra prediction modes of neighboring blocks adjacent to the target block, and information for prediction may be entropy-encoded/entropy-decoded.

For example, when the intra prediction modes of the target block and the neighboring block are identical to each other, the intra prediction modes of the target block and the neighboring block may be signaled to be identical using a predefined flag.

For example, an indicator indicating the same intra prediction mode as that of the target block among the intra prediction modes of the plurality of neighboring blocks may be signaled.

When the intra prediction modes of the target block and the neighboring block are different from each other, information regarding the intra prediction mode of the target block may be encoded and/or decoded using entropy encoding and/or entropy decoding.

Fig. 8 is a diagram illustrating reference samples used in an intra prediction process.

The reconstructed reference samples for intra prediction of the target block may include a lower left reference sample, a left reference sample, an upper right reference sample, and an upper right reference sample.

For example, the left reference sample point may represent a reconstructed reference pixel adjacent to the left side of the target block. The upper reference sample point may represent a reconstructed reference pixel adjacent to the top of the target block. The upper left reference sample point may represent a reconstructed reference pixel located at the upper left corner of the target block. The lower-left reference sampling point may represent a reference sampling point located below a left side sampling point line composed of the left reference sampling points among sampling points located on the same line as the left side sampling point line. The upper right reference sampling point may represent a reference sampling point located at the right side of an upper sampling point line composed of the upper reference sampling points among sampling points located on the same line as the upper sampling point line.

When the size of the target block is N × N, the numbers of the lower-left reference samples, the upper reference samples, and the upper-right reference samples may all be N.

By performing intra prediction on the target block, a prediction block may be generated. The process of generating the prediction block may include determining values of pixels in the prediction block. The sizes of the target block and the prediction block may be the same.

The reference sampling point used for intra prediction of the target block may be changed according to the intra prediction mode of the target block. The direction of the intra prediction mode may represent a dependency between the reference samples and the pixels of the prediction block. For example, a value specifying a reference sample may be used as a value of one or more specified pixels in the prediction block. In this case, the specified reference samples and the one or more specified pixels in the prediction block may be samples and pixels located on a straight line along a direction of the intra prediction mode. In other words, the value of the specified reference sample point may be copied as the value of the pixel located in the direction opposite to the direction of the intra prediction mode. Alternatively, the value of a pixel in the prediction block may be a value of a reference sample point located in the direction of the intra prediction mode with respect to the position of the pixel.

In an example, when the intra prediction mode of the target block is a vertical mode, the upper reference sampling point may be used for intra prediction. When the intra prediction mode is a vertical mode, the value of a pixel in the prediction block may be a value of a reference sample point vertically located above the position of the pixel. Therefore, the upper reference samples adjacent to the top of the target block may be used for intra prediction. In addition, the values of pixels in a row of the prediction block may be the same as those of the pixels of the upper reference sample point.

In an example, when the intra prediction mode of the target block is a horizontal mode, the left reference sample may be used for intra prediction. When the intra prediction mode is a horizontal mode, the value of a pixel in the prediction block may be a value of a reference sample horizontally located to the left of the position of the pixel. Therefore, the left reference samples adjacent to the left side of the target block may be used for intra prediction. Furthermore, the values of pixels in a column of the prediction block may be the same as the values of pixels of the left reference sample point.

In an example, when a mode value of an intra prediction mode of the current block is 34, at least some of the left reference samples, the upper-left corner reference samples, and at least some of the upper reference samples may be used for intra prediction. When the mode value of the intra prediction mode is 18, the value of a pixel in the prediction block may be a value of a reference sample point located diagonally at an upper left corner of the pixel.

Further, in the case of an intra prediction mode in which the mode value is a value ranging from 52 to 66, at least a portion of the upper-right reference samples may be used for intra prediction.

Further, in the case of an intra prediction mode in which the mode value is a value ranging from 2 to 17, at least a portion of the lower left reference samples may be used for intra prediction.

Further, in the case of an intra prediction mode in which the mode value is a value ranging from 19 to 49, the upper left reference sample may be used for intra prediction.

The number of reference samples used to determine the pixel value of one pixel in the prediction block may be 1 or 2 or more.

As described above, the pixel values of the pixels in the prediction block may be determined according to the positions of the pixels and the positions of the reference samples indicated by the direction of the intra prediction mode. When the position of the pixel and the position of the reference sample point indicated by the direction of the intra prediction mode are integer positions, the value of one reference sample point indicated by the integer position may be used to determine the pixel value of the pixel in the prediction block.

When the position of the pixel and the position of the reference sample point indicated by the direction of the intra prediction mode are not integer positions, an interpolated reference sample point based on two reference sample points closest to the position of the reference sample point may be generated. The values of the interpolated reference samples may be used to determine pixel values for pixels in the prediction block. In other words, when the position of the pixel in the prediction block and the position of the reference sample point indicated by the direction of the intra prediction mode indicate a position between two reference sample points, an interpolation based on the values of the two sample points may be generated.

The prediction block generated via prediction may be different from the original target block. In other words, there may be a prediction error, which is a difference between the target block and the prediction block, and there may also be a prediction error between pixels of the target block and pixels of the prediction block.

Hereinafter, the terms "difference", "error" and "residual" may be used to have the same meaning and may be used interchangeably with each other.

For example, in the case of directional intra prediction, the longer the distance between the pixels of the predicted block and the reference sample point is, the larger the prediction error that may occur. Such a prediction error may cause discontinuity between the generated prediction block and the neighboring block.

To reduce the prediction error, a filtering operation for the prediction block may be used. The filtering operation may be configured to adaptively apply a filter to a region in the prediction block that is considered to have a large prediction error. For example, a region considered to have a large prediction error may be a boundary of a prediction block. In addition, regions that are considered to have a large prediction error in a prediction block may be different according to an intra prediction mode, and characteristics of a filter may also be different according to the intra prediction mode.

As shown in fig. 8, for intra prediction of a target block, at least one of reference line 0 to reference line 3 may be used. Each reference line may indicate a reference sample line. When the number of reference lines is smaller, reference sample line closer to the target block may be indicated.

The samples in segment a and segment F may be obtained by padding using the samples in segment B and segment E that are closest to the target block, rather than from reconstructed neighboring blocks.

Index information indicating a reference sample line to be used for intra prediction of a target block may be signaled. The index information may indicate a reference sample line of the plurality of reference sample lines to be used for intra prediction of the target block. For example, the index information may have a value corresponding to any one of 0 to 3.

When the upper boundary of the target block is the boundary of the CTU, only the reference sample line 0 may be available. Therefore, in this case, the index information may not be signaled. When an additional reference sample line other than the reference sample line 0 is used, filtering of a prediction block, which will be described later, may not be performed.

In the case of inter-color intra prediction, a prediction block of a target block of a second color component may be generated based on a corresponding reconstructed block of a first color component.

For example, the first color component may be a luminance component and the second color component may be a chrominance component.

To perform inter-color intra prediction, parameters of a linear model between the first color component and the second color component may be derived based on the template.

The template may include reference samples (upper reference samples) above the target block and/or reference samples (left reference samples) to the left of the target block, and may include upper reference samples and/or left reference samples of a reconstructed block of the first color component corresponding to the reference samples.

For example, the following values may be used to derive the parameters of the linear model: 1) a value of a sample point of a first color component having a maximum value among sample points in the template, 2) a value of a sample point of a second color component corresponding to a sample point of the first color component, 3) a value of a sample point of a first color component having a minimum value among sample points in the template, and 4) a value of a sample point of a second color component corresponding to a sample point of the first color component.

When the parameters of the linear model are derived, the prediction block of the target block may be generated by applying the corresponding reconstructed block to the linear model.

According to the image format, subsampling may be performed on samples adjacent to the reconstructed block of the first color component and the corresponding reconstructed block of the first color component. For example, when one sampling point of the second color component corresponds to four sampling points of the first color component, one corresponding sampling point may be calculated by performing sub-sampling on the four sampling points of the first color component. When performing sub-sampling, derivation of parameters of the linear model and inter-color intra prediction may be performed based on the sub-sampled corresponding sampling points.

Information regarding whether to perform inter-color intra prediction and/or the range of templates may be signaled in intra prediction mode.

The target block may be partitioned into two or four sub-blocks in the horizontal direction and/or the vertical direction.

The sub-blocks generated by the partitioning may be sequentially reconstructed. That is, when intra prediction is performed on each sub-block, sub-prediction blocks of the sub-block may be generated. Further, when inverse quantization (inverse quantization) and/or inverse transformation is performed on each sub-block, a sub-residual block for the corresponding sub-block may be generated. The reconstructed sub-block may be generated by adding the sub-prediction block to the sub-residual block. The reconstructed sub-block may be used as a reference sample point for intra prediction of a sub-block having a next priority.

A sub-block may be a block that includes a certain number (e.g., 16) or more samples. For example, when the target block is an 8 × 4 block or a 4 × 8 block, the target block may be partitioned into two sub-blocks. Further, when the target block is a 4 × 4 block, the target block cannot be partitioned into sub-blocks. When the target block has another size, the target block may be partitioned into four sub-blocks.

Information on whether to perform intra prediction based on the sub-blocks and/or information on a partition direction (horizontal direction or vertical direction) may be signaled.

Such sub-block based intra prediction may be restricted such that it is performed only when the reference sample line 0 is used. When the sub-block-based intra prediction is performed, filtering of a prediction block, which will be described below, may not be performed.

The final prediction block may be generated by performing filtering on the prediction block generated through intra prediction.

The filtering may be performed by applying a specific weight to the filtering target samples, the left reference samples, the upper reference samples, and/or the upper left reference samples, which are targets to be filtered.

The weight for filtering and/or the reference samples (e.g., the range of the reference samples, the location of the reference samples, etc.) may be determined based on at least one of the block size, the intra prediction mode, and the location of the filtering target samples in the prediction block.

For example, the filtering may be performed only in a specific intra prediction mode (e.g., DC mode, planar mode, vertical mode, horizontal mode, diagonal mode, and/or adjacent diagonal mode).

The adjacent diagonal patterns may be patterns having numbers obtained by adding k to the numbers of the diagonal patterns, and may be patterns having numbers obtained by subtracting k from the numbers of the diagonal patterns. In other words, the number of the adjacent diagonal patterns may be the sum of the number of the diagonal patterns and k, or may be the difference between the number of the diagonal patterns and k. For example, k may be a positive integer of 8 or less.

The intra prediction mode of the target block may be derived using intra prediction modes of neighboring blocks existing near the target block, and such derived intra prediction modes may be entropy-encoded and/or entropy-decoded.

For example, when the intra prediction mode of the target block is the same as the intra prediction modes of the neighboring blocks, information indicating that the intra prediction mode of the target block is the same as the intra prediction modes of the neighboring blocks may be signaled using the specific flag information.

Also, for example, indicator information of neighboring blocks of which an intra prediction mode among intra prediction modes of a plurality of neighboring blocks is the same as an intra prediction mode of a target block may be signaled.

For example, when the intra prediction mode of the target block is different from the intra prediction modes of the neighboring blocks, entropy encoding and/or entropy decoding may be performed on information regarding the intra prediction mode of the target block by performing entropy encoding and/or entropy decoding based on the intra prediction modes of the neighboring blocks.

Fig. 9 is a diagram for explaining an embodiment of an inter prediction process.

The rectangle shown in fig. 9 may represent an image (or picture). In addition, in fig. 9, an arrow may indicate a prediction direction. The arrow pointing from the first picture to the second picture indicates that the second picture refers to the first picture. That is, each image may be encoded and/or decoded according to a prediction direction.

Images can be classified into an intra picture (I picture), a mono prediction picture or a predictive coded picture (P picture), and a bi prediction picture or a bi predictive coded picture (B picture) according to coding types. Each picture may be encoded and/or decoded according to its coding type.

When the target image that is the target to be encoded is an I picture, the target image can be encoded using data contained in the image itself without performing inter prediction with reference to other images. For example, an I picture may be encoded via intra prediction only.

When the target image is a P picture, the target image may be encoded via inter prediction using a reference picture existing in one direction. Here, the one direction may be a forward direction or a backward direction.

When the target image is a B picture, the image may be encoded via inter prediction using reference pictures existing in both directions, or may be encoded via inter prediction using reference pictures existing in one of a forward direction and a backward direction. Here, the two directions may be a forward direction and a backward direction.

P-pictures and B-pictures encoded and/or decoded using reference pictures may be considered images using inter prediction.

Hereinafter, inter prediction in the inter mode according to the embodiment will be described in detail.

Inter prediction or motion compensation may be performed using the reference picture and the motion information.

In the inter mode, the encoding apparatus 100 may perform inter prediction and/or motion compensation on the target block. The decoding apparatus 200 may perform inter prediction and/or motion compensation corresponding to the inter prediction and/or motion compensation performed by the encoding apparatus 100 on the target block.

The motion information of the target block may be separately derived by the encoding apparatus 100 and the decoding apparatus 200 during inter prediction. The motion information may be derived using motion information of reconstructed neighboring blocks, motion information of a col block, and/or motion information of blocks adjacent to the col block.

For example, the encoding apparatus 100 or the decoding apparatus 200 may perform prediction and/or motion compensation by using motion information of a spatial candidate and/or a temporal candidate as motion information of a target block. The target block may represent a PU and/or a PU partition.

The spatial candidate may be a reconstructed block spatially adjacent to the target block.

The temporal candidate may be a reconstructed block corresponding to the target block in a previously reconstructed co-located picture (col picture).

In the inter prediction, the encoding apparatus 100 and the decoding apparatus 200 may improve encoding efficiency and decoding efficiency by using motion information of spatial candidates and/or temporal candidates. The motion information of the spatial candidates may be referred to as "spatial motion information". The motion information of the temporal candidates may be referred to as "temporal motion information".

In the following, the motion information of the spatial candidate may be the motion information of the PU including the spatial candidate. The motion information of the temporal candidate may be the motion information of the PU including the temporal candidate. The motion information of the candidate block may be motion information of a PU that includes the candidate block.

Inter prediction may be performed using a reference picture.

The reference picture may be at least one of a picture preceding the target picture and a picture following the target picture. The reference picture may be an image used for prediction of the target block.

In inter prediction, a region in a reference picture may be specified using a reference picture index (or refIdx) indicating the reference picture, a motion vector to be described later, or the like. Here, the area specified in the reference picture may indicate a reference block.

Inter prediction may select a reference picture, and may also select a reference block corresponding to the target block from the reference picture. Further, inter prediction may generate a prediction block for a target block using the selected reference block.

The motion information may be derived by each of the encoding apparatus 100 and the decoding apparatus 200 during inter prediction.

The spatial candidates may be 1) blocks that exist in the target picture that 2) have been previously reconstructed via encoding and/or decoding and 3) are adjacent to the target block or located at corners of the target block. Here, the "block located at a corner of the target block" may be a block vertically adjacent to an adjacent block horizontally adjacent to the target block, or a block horizontally adjacent to an adjacent block vertically adjacent to the target block. Further, "a block located at a corner of the target block" may have the same meaning as "a block adjacent to the corner of the target block". The meaning of "a block located at a corner of a target block" may be included in the meaning of "a block adjacent to the target block".

For example, the spatial candidate may be a reconstructed block located to the left of the target block, a reconstructed block located above the target block, a reconstructed block located in the lower left corner of the target block, a reconstructed block located in the upper right corner of the target block, or a reconstructed block located in the upper left corner of the target block.

Each of the encoding apparatus 100 and the decoding apparatus 200 can identify a block existing in a position spatially corresponding to a target block in a col picture. The position of the target block in the target picture and the position of the identified block in the col picture may correspond to each other.

Each of the encoding apparatus 100 and the decoding apparatus 200 may determine, as a time candidate, a col block existing at a predefined correlation position with respect to the identified block. The predefined relative location may be a location that exists inside and/or outside the identified block.

For example, the col blocks may include a first col block and a second col block. When the coordinates of the identified block are (xP, yP) and the size of the identified block is represented by (nPSW, nPSH), the first col block may be a block located at coordinates (xP + nPSW, yP + nPSH). The second col block may be a block located at coordinates (xP + (nPSW > >1), yP + (nPSH > > 1)). When the first col block is not available, the second col block may be selectively used.

The motion vector of the target block may be determined based on the motion vector of the col block. Each of the encoding apparatus 100 and the decoding apparatus 200 may scale the motion vector of the col block. The scaled motion vector of the col block can be used as the motion vector of the target block. Further, the motion vector of the motion information of the temporal candidate stored in the list may be a scaled motion vector.

The ratio of the motion vector of the target block relative to the motion vector of the col block may be the same as the ratio of the first temporal distance relative to the second temporal distance. The first temporal distance may be a distance between the reference picture and a target picture of the target block. The second temporal distance may be a distance between the reference picture and a col picture of the col block.

The scheme for deriving the motion information may vary according to the inter prediction mode of the target block. For example, as an inter prediction mode applied to inter prediction, there may be an Advanced Motion Vector Predictor (AMVP) mode, a merge mode, a skip mode, a merge mode with a motion vector difference, a sub-block merge mode, a triangle partition mode, an inter-intra combined prediction mode, an affine inter mode, a current picture reference mode, and the like. The merge mode may also be referred to as a "motion merge mode". Each mode will be described in detail below.

1) AMVP mode

When using the AMVP mode, the encoding apparatus 100 may search for similar blocks in the neighborhood of the target block. The encoding apparatus 100 may acquire a prediction block by performing prediction on a target block using motion information of the found similar block. The encoding apparatus 100 may encode a residual block that is a difference between the target block and the prediction block.

1-1) creating a list of predicted motion vector candidates

When the AMVP mode is used as the prediction mode, each of the encoding apparatus 100 and the decoding apparatus 200 may create a list of predicted motion vector candidates using a motion vector of a spatial candidate, a motion vector of a temporal candidate, and a zero vector. The predicted motion vector candidate list may include one or more predicted motion vector candidates. At least one of a motion vector of the spatial candidate, a motion vector of the temporal candidate, and a zero vector may be determined and used as the prediction motion vector candidate.

Hereinafter, the terms "prediction motion vector (candidate)" and "motion vector (candidate)" may be used to have the same meaning and may be used interchangeably with each other.

Hereinafter, the terms "prediction motion vector candidate" and "AMVP candidate" may be used to have the same meaning and may be used interchangeably with each other.

Hereinafter, the terms "predicted motion vector candidate list" and "AMVP candidate list" may be used to have the same meaning and may be used interchangeably with each other.

The spatial candidates may comprise reconstructed spatially neighboring blocks. In other words, the motion vectors of the reconstructed neighboring blocks may be referred to as "spatial prediction motion vector candidates".

The temporal candidates may include a col block and blocks adjacent to the col block. In other words, a motion vector of a col block or a motion vector of a block adjacent to the col block may be referred to as a "temporal prediction motion vector candidate".

The zero vector may be a (0,0) motion vector.

The predicted motion vector candidate may be a motion vector predictor for predicting a motion vector. Further, in the encoding apparatus 100, each predicted motion vector candidate may be an initial search position for a motion vector.

1-2) searching for motion vector using list of predicted motion vector candidates

The encoding apparatus 100 may determine a motion vector to be used for encoding the target block within the search range using the list of predicted motion vector candidates. Further, the encoding apparatus 100 may determine a predicted motion vector candidate to be used as the predicted motion vector of the target block among the predicted motion vector candidates existing in the predicted motion vector candidate list.

The motion vector to be used for encoding the target block may be a motion vector that can be encoded at a minimum cost.

In addition, the encoding apparatus 100 may determine whether to encode the target block using the AMVP mode.

1-3) Transmission of inter-frame prediction information

The encoding apparatus 100 may generate a bitstream including inter prediction information required for inter prediction. The decoding apparatus 200 may perform inter prediction on the target block using inter prediction information of the bitstream.

The inter prediction information may include 1) mode information indicating whether the AMVP mode is used, 2) a prediction motion vector index, 3) a Motion Vector Difference (MVD), 4) a reference direction, and 5) a reference picture index.

Hereinafter, the terms "prediction motion vector index" and "AMVP index" may be used to have the same meaning and may be used interchangeably with each other.

Furthermore, the inter prediction information may include a residual signal.

When the mode information indicates that the AMVP mode is used, the decoding apparatus 200 may acquire a prediction motion vector index, an MVD, a reference direction, and a reference picture index from the bitstream through entropy decoding.

The prediction motion vector index may indicate a prediction motion vector candidate to be used for predicting the target block among prediction motion vector candidates included in the prediction motion vector candidate list.

1-4) inter prediction in AMVP mode using inter prediction information

The decoding apparatus 200 may derive a predicted motion vector candidate using the predicted motion vector candidate list, and may determine motion information of the target block based on the derived predicted motion vector candidate.

The decoding apparatus 200 may determine a motion vector candidate for the target block among the predicted motion vector candidates included in the predicted motion vector candidate list using the predicted motion vector index. The decoding apparatus 200 may select a predicted motion vector candidate indicated by the predicted motion vector index as the predicted motion vector of the target block from among the predicted motion vector candidates included in the predicted motion vector candidate list.

The encoding apparatus 100 may generate an entropy-encoded prediction motion vector index by applying entropy encoding to the prediction motion vector index, and may generate a bitstream including the entropy-encoded prediction motion vector index. The entropy-encoded prediction motion vector index may be signaled from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may extract an entropy-encoded prediction motion vector index from a bitstream, and may acquire the prediction motion vector index by applying entropy decoding to the entropy-encoded prediction motion vector index.

The motion vector that is actually to be used for inter prediction of the target block may not match the predicted motion vector. To indicate the difference between the motion vector that will actually be used for inter-predicting the target block and the predicted motion vector, MVD may be used. The encoding apparatus 100 may derive a prediction motion vector similar to a motion vector that will actually be used for inter-prediction of the target block in order to use an MVD as small as possible.

The MVD may be the difference between the motion vector of the target block and the predicted motion vector. The encoding apparatus 100 may calculate an MVD and may generate an entropy-encoded MVD by applying entropy encoding to the MVD. The encoding apparatus 100 may generate a bitstream including the entropy-encoded MVDs.

The MVD may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may extract entropy-encoded MVDs from the bitstream and may acquire the MVDs by applying entropy decoding to the entropy-encoded MVDs.

The decoding apparatus 200 may derive a motion vector of the target block by summing the MVD and the prediction motion vector. In other words, the motion vector of the target block derived by the decoding apparatus 200 may be the sum of the MVD and the motion vector candidate.

Also, the encoding apparatus 100 may generate entropy-encoded MVD resolution information by applying entropy encoding to the calculated MVD resolution information, and may generate a bitstream including the entropy-encoded MVD resolution information. The decoding apparatus 200 may extract entropy-encoded MVD resolution information from a bitstream, and may acquire the MVD resolution information by applying entropy decoding to the entropy-encoded MVD resolution information. The decoding apparatus 200 may adjust the resolution of the MVD using the MVD resolution information.

In addition, the encoding apparatus 100 may calculate the MVD based on an affine model. The decoding apparatus 200 may derive an affine control motion vector of the target block by the sum of the MVD and the affine control motion vector candidate, and may derive a motion vector of the sub-block using the affine control motion vector.

The reference direction may indicate a list of reference pictures to be used for predicting the target block. For example, the reference direction may indicate one of the reference picture list L0 and the reference picture list L1.

The reference direction indicates only a reference picture list to be used for prediction of the target block, and may not mean that the direction of the reference picture is limited to a forward direction or a backward direction. In other words, each of the reference picture list L0 and the reference picture list L1 may include pictures in the forward direction and/or the backward direction.

The reference direction being unidirectional may mean that a single reference picture list is used. The reference direction being bi-directional may mean that two reference picture lists are used. In other words, the reference direction may indicate one of the following: the case of using only the reference picture list L0, the case of using only the reference picture list L1, and the case of using two reference picture lists.

The reference picture index may indicate a reference picture for the prediction target block among reference pictures existing in the reference picture list. The encoding apparatus 100 may generate an entropy-encoded reference picture index by applying entropy encoding to the reference picture index, and may generate a bitstream including the entropy-encoded reference picture index. The entropy-encoded reference picture index may be signaled from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may extract an entropy-encoded reference picture index from a bitstream, and may acquire the reference picture index by applying entropy decoding to the entropy-encoded reference picture index.

When two reference picture lists are used for prediction of a target block, a single reference picture index and a single motion vector may be used for each of the reference picture lists. Further, when two reference picture lists are used for predicting the target block, two prediction blocks may be specified for the target block. For example, an average or a weighted sum of two prediction blocks for a target block may be used to generate a (final) prediction block for the target block.

The motion vector of the target block may be derived by predicting a motion vector index, an MVD, a reference direction, and a reference picture index.

The decoding apparatus 200 may generate a prediction block for the target block based on the derived motion vector and the reference picture index. For example, the prediction block may be a reference block indicated by a derived motion vector in a reference picture indicated by a reference picture index.

Since the prediction motion vector index and the MVD are encoded while the motion vector of the target block itself is not encoded, the number of bits transmitted from the encoding apparatus 100 to the decoding apparatus 200 may be reduced and the encoding efficiency may be improved.

For the target block, motion information of the reconstructed neighboring blocks may be used. In a specific inter prediction mode, the encoding apparatus 100 may not encode actual motion information of the target block separately. The motion information of the target block is not encoded, but additional information that enables the motion information of the target block to be derived using the reconstructed motion information of the neighboring blocks may be encoded. Since the additional information is encoded, the number of bits transmitted to the decoding apparatus 200 may be reduced and the encoding efficiency may be improved.

For example, as an inter prediction mode in which motion information of a target block is not directly encoded, a skip mode and/or a merge mode may exist. Here, each of the encoding apparatus 100 and the decoding apparatus 200 may use an identifier and/or an index indicating a unit of which motion information is to be used as motion information of the target unit among the reconstructed neighboring units.

2) Merge mode

As a scheme for deriving motion information of a target block, there is merging. The term "merging" may mean merging motion of multiple blocks. "merging" may mean that motion information of one block is also applied to other blocks. In other words, the merge mode may be a mode in which motion information of the target block is derived from motion information of neighboring blocks.

When the merge mode is used, the encoding apparatus 100 may predict motion information of the target block using motion information of the spatial candidate and/or motion information of the temporal candidate. The spatial candidates may include reconstructed spatially neighboring blocks that are spatially adjacent to the target block. The spatially neighboring blocks may include a left neighboring block and an upper neighboring block. The temporal candidates may include col blocks. The terms "spatial candidate" and "spatial merge candidate" may be used to have the same meaning and may be used interchangeably with each other. The terms "time candidate" and "time merge candidate" may be used to have the same meaning and may be used interchangeably with each other.

The encoding apparatus 100 may acquire a prediction block via prediction. The encoding apparatus 100 may encode a residual block that is a difference between the target block and the prediction block.

2-1) creating a merge candidate list

When the merge mode is used, each of the encoding apparatus 100 and the decoding apparatus 200 may create a merge candidate list using motion information of spatial candidates and/or motion information of temporal candidates. The motion information may include 1) a motion vector, 2) a reference picture index, and 3) a reference direction. The reference direction may be unidirectional or bidirectional. The reference direction may represent an inter prediction indicator.

The merge candidate list may include merge candidates. The merge candidate may be motion information. In other words, the merge candidate list may be a list storing a plurality of pieces of motion information.

The merge candidate may be motion information of a plurality of temporal candidates and/or spatial candidates. In other words, the merge candidate list may include motion information of temporal candidates and/or spatial candidates, and the like.

Further, the merge candidate list may include a new merge candidate generated by combining merge candidates already existing in the merge candidate list. In other words, the merge candidate list may include new motion information generated by combining a plurality of pieces of motion information previously existing in the merge candidate list.

Further, the merge candidate list may include history-based merge candidates. The history-based merge candidate may be motion information of a block that is encoded and/or decoded before the target block.

Further, the merge candidate list may include merge candidates based on an average of the two merge candidates.

The merge candidate may be a specific mode of deriving inter prediction information. The merge candidate may be information indicating a specific mode of deriving inter prediction information. Inter prediction information for the target block may be derived from a particular mode indicated by the merge candidate. Further, the particular mode may include a process of deriving a series of inter prediction information. This particular mode may be an inter prediction information derivation mode or a motion information derivation mode.

The inter prediction information of the target block may be derived according to a mode indicated by a merge candidate selected among merge candidates in the merge candidate list by a merge index.

For example, the motion information derivation mode in the merge candidate list may be at least one of the following modes: 1) a motion information derivation mode for sub-block units and 2) an affine motion information derivation mode.

In addition, the merge candidate list may include motion information of a zero vector. The zero vector may also be referred to as a "zero merge candidate".

In other words, the pieces of motion information in the merge candidate list may be at least one of: 1) motion information of a spatial candidate, 2) motion information of a temporal candidate, 3) motion information generated by combining pieces of motion information previously existing in the merge candidate list, and 4) a zero vector.

The motion information may include 1) a motion vector, 2) a reference picture index, and 3) a reference direction. The reference direction may also be referred to as an "inter prediction indicator". The reference direction may be unidirectional or bidirectional. The unidirectional reference direction may indicate L0 prediction or L1 prediction.

The merge candidate list may be created before performing prediction in merge mode.

The number of merge candidates in the merge candidate list may be predefined. Each of the encoding apparatus 100 and the decoding apparatus 200 may add the merge candidates to the merge candidate list according to a predefined scheme and a predefined priority such that the merge candidate list has a predefined number of merge candidates. The merge candidate list of the encoding apparatus 100 and the merge candidate list of the decoding apparatus 200 may be made identical to each other using a predefined scheme and a predefined priority.

Merging may be applied on a CU or PU basis. When the merging is performed on a CU or PU basis, the encoding apparatus 100 may transmit a bitstream including predefined information to the decoding apparatus 200. For example, the predefined information may include 1) information indicating whether to perform merging for respective block partitions, and 2) information on a block on which merging is to be performed among blocks that are spatial candidates and/or temporal candidates for a target block.

2-2) searching for motion vector using merge candidate list

The encoding apparatus 100 may determine a merging candidate to be used for encoding the target block. For example, the encoding apparatus 100 may perform prediction on the target block using the merge candidate in the merge candidate list, and may generate a residual block for the merge candidate. The encoding apparatus 100 may encode the target block using a merging candidate that generates the minimum cost in the encoding of the prediction and residual blocks.

In addition, the encoding apparatus 100 may determine whether to encode the target block using the merge mode.

2-3) for inter-frame prediction informationTransmission of

The encoding apparatus 100 may generate a bitstream including inter prediction information required for inter prediction. The encoding apparatus 100 may generate entropy-encoded inter prediction information by performing entropy encoding on the inter prediction information, and may transmit a bitstream including the entropy-encoded inter prediction information to the decoding apparatus 200. The entropy-encoded inter prediction information may be signaled by the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may extract entropy-encoded inter prediction information from a bitstream, and may acquire the inter prediction information by applying entropy decoding to the entropy-encoded inter prediction information.

The decoding apparatus 200 may perform inter prediction on the target block using inter prediction information of the bitstream.

The inter prediction information may include 1) mode information indicating whether a merge mode is used, 2) a merge index, and 3) correction information.

Furthermore, the inter prediction information may include a residual signal.

The decoding apparatus 200 may acquire the merge index from the bitstream only when the mode information indicates that the merge mode is used.

The mode information may be a merge flag. The unit of the mode information may be a block. The information on the block may include mode information, and the mode information may indicate whether a merge mode is applied to the block.

The merge index may indicate a merge candidate to be used for prediction of the target block among merge candidates included in the merge candidate list. Alternatively, the merge index may indicate a block to be merged with the target block among neighboring blocks spatially or temporally adjacent to the target block.

The encoding apparatus 100 may select a merge candidate having the highest encoding performance among merge candidates included in the merge candidate list, and set a value of the merge index to indicate the selected merge candidate.

The correction information may be information for correcting a motion vector. The encoding apparatus 100 may generate correction information. The decoding apparatus 200 may correct the motion vector of the merge candidate selected by the merge index based on the correction information.

The correction information may include at least one of information indicating whether correction is to be performed, correction direction information, and correction size information. The prediction mode for correcting the motion vector based on the signaled correction information may be referred to as a "merge mode with motion vector difference".

2-4) inter prediction of merge mode using inter prediction information

The decoding apparatus 200 may perform prediction on the target block using a merge candidate indicated by the merge index among merge candidates included in the merge candidate list.

The motion vector of the target block may be specified by the motion vector of the merging candidate indicated by the merging index, the reference picture index, and the reference direction.

3) Skip mode

The skip mode may be a mode in which motion information of a spatial candidate or motion information of a temporal candidate is applied to the target block without change. Also, the skip mode may be a mode that does not use a residual signal. In other words, when the skip mode is used, the reconstructed block may be the same as the predicted block.

The difference between the merge mode and the skip mode is whether a residual signal is sent or used. That is, the skip mode may be similar to the merge mode except that no residual signal is sent or used.

When the skip mode is used, the encoding apparatus 100 may transmit information on a block whose motion information is to be used as motion information of a target block among blocks that are spatial candidates or temporal candidates to the decoding apparatus 200 through a bitstream. The encoding apparatus 100 may generate entropy-encoded information by performing entropy encoding on the information, and may signal the entropy-encoded information to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may extract entropy-encoded information from a bitstream and may acquire the information by applying entropy decoding to the entropy-encoded information.

Also, when the skip mode is used, the encoding apparatus 100 may not send other syntax information (such as MVD) to the decoding apparatus 200. For example, when the skip mode is used, the encoding apparatus 100 may not signal syntax elements related to at least one of an MVD, a coded block flag, and a transform coefficient level to the decoding apparatus 200.

3-1) creating a merge candidate list

The skip mode may also use a merge candidate list. In other words, the merge candidate list may be used in both the merge mode and the skip mode. In this regard, the merge candidate list may also be referred to as a "skip candidate list" or a "merge/skip candidate list".

Alternatively, the skip mode may use an additional candidate list different from the candidate list of the merge mode. In this case, in the following description, the merge candidate list and the merge candidate may be replaced with the skip candidate list and the skip candidate, respectively.

The merge candidate list may be created before performing prediction in skip mode.

3-2) searching for motion vector using merge candidate list

The encoding apparatus 100 may determine a merge candidate to be used for encoding the target block. For example, the encoding apparatus 100 may perform prediction on the target block using the merge candidate in the merge candidate list. The encoding apparatus 100 may encode the target block using the merge candidate that generates the smallest cost in the prediction.

In addition, the encoding apparatus 100 may determine whether to encode the target block using the skip mode.

3-3) Transmission of inter-frame prediction information

The inter prediction information may include 1) mode information indicating whether a skip mode is used and 2) a skip index.

The skip index may be the same as the merge index described above.

When the skip mode is used, the target block may be encoded without using a residual signal. The inter prediction information may not include a residual signal. Alternatively, the bitstream may not include a residual signal.

The decoding apparatus 200 may acquire the skip index from the bitstream only when the mode information indicates that the skip mode is used. As described above, the merge index and the skip index may be identical to each other. The decoding apparatus 200 may acquire the skip index from the bitstream only when the mode information indicates that the merge mode or the skip mode is used.

The skip index may indicate a merge candidate to be used for prediction of the target block among merge candidates included in the merge candidate list.

3-4) inter prediction in skip mode using inter prediction information

The decoding apparatus 200 may perform prediction on the target block using a merge candidate indicated by the skip index among merge candidates included in the merge candidate list.

The motion vector of the target block may be specified by the motion vector of the merging candidate indicated by the skip index, the reference picture index, and the reference direction.

4) Current picture reference mode

The current picture reference mode may represent a prediction mode: the prediction mode uses a previously reconstructed region in a target picture to which the target block belongs.

A motion vector specifying a previously reconstructed region may be used. The reference picture index of the target block may be used to determine whether the target block has been encoded in the current picture reference mode.

A flag or index indicating whether the target block is a block encoded in the current picture reference mode may be signaled by the encoding apparatus 100 to the decoding apparatus 200. Alternatively, whether the target block is a block encoded in the current picture reference mode may be inferred by the reference picture index of the target block.

When the target block is encoded in the current picture reference mode, the current picture may exist at a fixed position or an arbitrary position in the reference picture list for the target block.

For example, the fixed position may be a position where the value of the reference picture index is 0 or the last position.

When the target picture exists at an arbitrary position in the reference picture list, an additional reference picture index indicating such an arbitrary position may be signaled by the encoding apparatus 100 to the decoding apparatus 200.

5) Subblock merge mode

The sub-block merging mode may be a mode in which motion information is derived from sub-blocks of the CU.

When the subblock merge mode is applied, a subblock merge candidate list may be generated using motion information of a co-located subblock (col-sub-block) of a target subblock (i.e., a subblock-based temporal merge candidate) in a reference image and/or an affine control point motion vector merge candidate.

6) Triangular partition mode

In the triangle partition mode, the target block may be partitioned in a diagonal direction, and a child target block generated by the partitioning may be generated. For each sub-target block, motion information for the corresponding sub-target block may be derived, and the derived motion information may be used to derive a prediction sample for each sub-target block. The predicted samples of the target block may be derived by a weighted sum of the predicted samples of the sub-target blocks generated via partitioning.

7) Combined inter-intra prediction mode

The combined inter-intra prediction mode may be a mode in which a predicted sample of the target block is derived using a weighted sum of predicted samples generated via inter prediction and predicted samples generated via intra prediction.

In the above-described mode, the decoding apparatus 200 may autonomously correct the derived motion information. For example, the decoding apparatus 200 may search for motion information having a minimum Sum of Absolute Differences (SAD) in a specific region based on a reference block indicated by the derived motion information, and may derive the found motion information as corrected motion information.

In the above-described mode, the decoding apparatus 200 may compensate for prediction samples derived via inter prediction using optical flow.

In the AMVP mode, the merge mode, the skip mode, and the like described above, the index information of the list may be used to specify motion information to be used for prediction of the target block among pieces of motion information in the list.

In order to improve encoding efficiency, the encoding apparatus 100 may signal only an index of an element that generates the smallest cost in inter prediction of the target block among elements in the list. The encoding apparatus 100 may encode the index and may signal the encoded index.

Therefore, it is necessary to be able to derive the above-described lists (i.e., the predictive motion vector candidate list and the merge candidate list) based on the same data using the same scheme by the encoding apparatus 100 and the decoding apparatus 200. Here, the same data may include a reconstructed picture and a reconstructed block. Further, in order to specify an element using an index, the order of the elements in the list must be fixed.

Fig. 10 illustrates spatial candidates according to an embodiment.

In fig. 10, the positions of the spatial candidates are shown.

The large block at the center of the graph may represent the target block. Five small blocks may represent spatial candidates.

The coordinates of the target block may be (xP, yP), and the size of the target block may be represented by (nPSW, nPSH).

Spatial candidate A₀May be a block adjacent to the lower left corner of the target block. A. the₀May be a block occupying a pixel located at the coordinates (xP-1, yP + nPSH + 1).

Spatial candidate A₁May be the block adjacent to the left side of the target block. A. the ₁May be the lowermost block among blocks adjacent to the left side of the target block. Alternatively, A₁May be with A₀Top adjacent block of (a). A. the₁May be a block occupying pixels located at coordinates (xP-1, yP + nPSH).

Spatial candidate B₀May be a block adjacent to the upper right corner of the target block. B is₀May be occupied at coordinates (xP + nPSW +1, yP-1)A block of pixels.

Spatial candidate B₁May be a block adjacent to the top of the target block. B is₁May be the rightmost block among blocks adjacent to the top of the target block. Alternatively, B₁May be with B₀Left adjacent block. B is₁May be a block occupying a pixel located at the coordinates (xP + nPSW, yP-1).

Spatial candidate B₂May be a block adjacent to the upper left corner of the target block. B is₂May be a block occupying a pixel located at the coordinates (xP-1, yP-1).

Determination of availability of spatial and temporal candidates

In order to include motion information of a spatial candidate or motion information of a temporal candidate in a list, it must be determined whether motion information of a spatial candidate or motion information of a temporal candidate is available.

Hereinafter, the candidate block may include a spatial candidate and a temporal candidate.

For example, the determination may be performed by sequentially applying the following steps 1) to 4).

Step 1) when a PU including a candidate block is located outside the boundary of a picture, the availability of the candidate block may be set to "false". The expression "availability is set to false" may have the same meaning as "set to unavailable".

Step 2) when a PU including a candidate block is located outside the boundary of a slice, the availability of the candidate block may be set to "false". When the target block and the candidate block are located in different stripes, the availability of the candidate block may be set to "false".

Step 3) when the PU including the candidate block is outside the boundary of the parallel block, the availability of the candidate block may be set to "false". When the target block and the candidate block are located in different parallel blocks, the availability of the candidate block may be set to "false".

Step 4) when the prediction mode of the PU including the candidate block is an intra prediction mode, the availability of the candidate block may be set to "false". The availability of a candidate block may be set to "false" when a PU that includes the candidate block does not use inter prediction.

Fig. 11 illustrates an order of adding motion information of spatial candidates to a merge list according to an embodiment.

As shown in fig. 11, a may be used when pieces of motion information of spatial candidates are added to the merge list ₁、B₁、B₀、A₀And B₂The order of (a). That is, can be according to A₁、B₁、B₀、A₀And B₂The order of the available spatial candidates adds pieces of motion information of the available spatial candidates to the merge list.

Method for deriving merge lists in merge mode and skip mode

As described above, the maximum number of merging candidates in the merge list may be set. The maximum number of settings may be indicated by "N". The set number may be transmitted from the encoding apparatus 100 to the decoding apparatus 200. The head of the strip may comprise N. In other words, the maximum number of merging candidates in the merging list for the target block of the slice may be set by the slice header. For example, the value of N may be substantially 5.

Pieces of motion information (i.e., merging candidates) may be added to the merge list in the order of the following steps 1) to 4).

Step 1)Among the spatial candidates, the available spatial candidates may be added to the merge list. The pieces of motion information of the available spatial candidates may be added to the merge list in the order shown in fig. 10. Here, when the motion information of the available spatial candidate overlaps with other motion information already existing in the merge list, the motion information of the available spatial candidate may not be added to the merge list. The operation of checking whether the corresponding motion information overlaps with other motion information present in the list may be simply referred to as "overlap check".

The maximum number of pieces of motion information to be added may be N.

Step 2)When the number of pieces of motion information in the merge list is less than N and a temporal candidate is available, the motion information of the temporal candidate may be added to the merge list. Here, when the available time is a candidate for movementWhen motion information overlaps with other motion information already existing in the merge list, the motion information of the available temporal candidates may not be added to the merge list.

Step 3)When the number of pieces of motion information in the merge list is less than N and the type of the target slice is "B", combined motion information generated by combining bi-prediction (bi-prediction) may be added to the merge list.

The target stripe may be a stripe that includes the target block.

The combined motion information may be a combination of the L0 motion information and the L1 motion information. The L0 motion information may be motion information referring only to the reference picture list L0. The L1 motion information may be motion information referring only to the reference picture list L1.

In the merge list, there may be one or more pieces of L0 motion information. Further, in the merge list, there may be one or more pieces of L1 motion information.

The combined motion information may include one or more pieces of combined motion information. When generating the combined motion information, L0 motion information and L1 motion information, which will be used for the step of generating the combined motion information, among the one or more pieces of L0 motion information and the one or more pieces of L1 motion information, may be previously defined. One or more pieces of combined motion information may be generated in a predefined order via combined bi-prediction using a pair of different pieces of motion information in the merge list. One piece of motion information of the pair of different motion information may be L0 motion information, and the other piece of motion information of the pair of different motion information may be L1 motion information.

For example, the combined motion information added with the highest priority may be a combination of L0 motion information having a merge index of 0 and L1 motion information having a merge index of 1. When the motion information having the merge index 0 is not the L0 motion information or when the motion information having the merge index 1 is not the L1 motion information, the combined motion information may be neither generated nor added. Next, the combined motion information added with the next priority may be a combination of L0 motion information having a merge index of 1 and L1 motion information having a merge index of 0. The detailed combinations that follow may conform to other combinations in the video encoding/decoding field.

Here, when the combined motion information overlaps with other motion information already existing in the merge list, the combined motion information may not be added to the merge list.

Step 4)When the number of pieces of motion information in the merge list is less than N, the motion information of the zero vector may be added to the merge list.

The zero vector motion information may be motion information in which the motion vector is a zero vector.

The number of pieces of zero vector motion information may be one or more. The reference picture indices of one or more pieces of zero vector motion information may be different from each other. For example, the value of the reference picture index of the first zero vector motion information may be 0. The reference picture index of the second zero vector motion information may have a value of 1.

The number of pieces of zero vector motion information may be the same as the number of reference pictures in the reference picture list.

The reference direction of the zero vector motion information may be bi-directional. Both motion vectors may be zero vectors. The number of pieces of zero vector motion information may be the smaller one of the number of reference pictures in the reference picture list L0 and the number of reference pictures in the reference picture list L1. Alternatively, when the number of reference pictures in the reference picture list L0 and the number of reference pictures in the reference picture list L1 are different from each other, the reference direction, which is unidirectional, may be used for the reference picture index that can be applied to only a single reference picture list.

The encoding apparatus 100 and/or the decoding apparatus 200 may then add zero vector motion information to the merge list while changing the reference picture index.

Zero vector motion information may not be added to the merge list when it overlaps with other motion information already present in the merge list.

The order of the above-described steps 1) to 4) is merely exemplary, and may be changed. Furthermore, some of the above steps may be omitted according to predefined conditions.

Method for deriving predicted motion vector candidate list in AMVP mode

The maximum number of predicted motion vector candidates in the predicted motion vector candidate list may be predefined. A predefined maximum number may be indicated by N. For example, the predefined maximum number may be 2.

Pieces of motion information (i.e., predicted motion vector candidates) may be added to the predicted motion vector candidate list in the following order of step 1) to step 3).

Step 1)An available spatial candidate among the spatial candidates may be added to the predicted motion vector candidate list. The spatial candidates may include a first spatial candidate and a second spatial candidate.

The first spatial candidate may be a₀、A₁Scaled A₀And scaled A₁One of them. The second spatial candidate may be B₀、B₁、B₂Scaled B₀Scaled B₁And scaled B₂One of them.

The plurality of pieces of motion information of the available spatial candidates may be added to the prediction motion vector candidate list in the order of the first spatial candidate and the second spatial candidate. In this case, when the motion information of the available spatial candidate overlaps with other motion information already existing in the predicted motion vector candidate list, the motion information of the available spatial candidate may not be added to the predicted motion vector candidate list. In other words, when the value of N is 2, if the motion information of the second spatial candidate is the same as the motion information of the first spatial candidate, the motion information of the second spatial candidate may not be added to the predicted motion vector candidate list.

The maximum number of pieces of motion information to be added may be N.

Step 2)When the number of pieces of motion information in the predicted motion vector candidate list is less than N and a temporal candidate is available, the motion information of the temporal candidate may be added to the predicted motion vector candidate list. In this case, the motion information and the predicted motion vector candidate of the current time candidate are availableWhen other motion information already present in the selection list overlaps, the motion information of the available temporal candidates may not be added to the predicted motion vector candidate list.

Step 3)When the number of pieces of motion information in the predicted motion vector candidate list is less than N, zero vector motion information may be added to the predicted motion vector candidate list.

The zero vector motion information may include one or more pieces of zero vector motion information. The reference picture indices of the one or more pieces of zero vector motion information may be different from each other.

The encoding apparatus 100 and/or the decoding apparatus 200 may sequentially add pieces of zero vector motion information to the predicted motion vector candidate list while changing the reference picture index.

When the zero vector motion information overlaps with other motion information already existing in the predicted motion vector candidate list, the zero vector motion information may not be added to the predicted motion vector candidate list.

The description of zero vector motion information made above in connection with the merge list is also applicable to zero vector motion information. A repetitive description thereof will be omitted.

The order of step 1) to step 3) described above is merely exemplary and may be changed. Furthermore, some of the steps may be omitted according to predefined conditions.

Fig. 12 illustrates a transform and quantization process according to an example.

As shown in fig. 12, the quantized level may be generated by performing transform and/or quantization processing on the residual signal.

The residual signal may be generated as a difference between the original block and the prediction block. Here, the prediction block may be a block generated via intra prediction or inter prediction.

The residual signal may be transformed into a signal in the frequency domain by a transformation process as part of a quantization process.

The transform kernels used for the transform may include various DCT kernels, such as Discrete Cosine Transform (DCT) type 2(DCT-II) and Discrete Sine Transform (DST) kernels.

These transform kernels may perform separable transforms or two-dimensional (2D) inseparable transforms on the residual signal. The separable transform may be a transform indicating that a one-dimensional (1D) transform is performed on the residual signal in each of a horizontal direction and a vertical direction.

The DCT type and the DST type adaptively used for the 1D transform may include DCT-V, DCT-VIII, DST-I, and DST-VII in addition to DCT-II, as shown in each of Table 3 and Table 4 below.

TABLE 3

TABLE 4

Set of transformations	Transformation candidates
			0	DST-VII,DCT-VIII,DST-I
1	DST-VII,DST-I,DCT-VIII
		2	DST-VII,DCT-V,DST-I

As shown in tables 3 and 4, when a DCT type or a DST type to be used for transformation is derived, a transformation set may be used. Each transform set may include a plurality of transform candidates. Each transform candidate may be a DCT type or a DST type.

Table 5 below shows an example of a transform set to be applied to the horizontal direction and a transform set to be applied to the vertical direction according to the intra prediction mode.

TABLE 5

Intra prediction mode	0	1	2	3	4	5	6	7	8	9
											Vertical transformation set	2	1	0	1	0	1	0	1	0	1
Set of horizontal transformations	2	1	0	1	0	1	0	1	0	1
											Intra prediction mode	10	11	12	13	14	15	16	17	18	19
Vertical direction transformation set	0	1	0	1	0	0	0	0	0	0
											Horizontal direction transformation set	0	1	0	1	2	2	2	2	2	2
Intra prediction mode	20	21	22	23	24	25	26	27	28	29
											Vertical direction transformation set	0	0	0	1	0	1	0	1	0	1
Horizontal direction transformation set	2	2	2	1	0	1	0	1	0	1
											Intra prediction mode	30	31	32	33	34	35	36	37	38	39
Vertical direction transformation set	0	1	0	1	0	1	0	1	0	1
											Horizontal direction changeCollection	0	1	0	1	0	1	0	1	0	1
Intra prediction mode	40	41	42	43	44	45	46	47	48	49
											Vertical direction transformation set	0	1	0	1	0	1	2	2	2	2
Horizontal direction transformation set	0	1	0	1	0	1	0	0	0	0
											Intra prediction mode	50	51	52	53	54	55	56	57	58	59
Vertical direction transformation set	2	2	2	2	2	1	0	1	0	1
											Horizontal direction transformation set	0	0	0	0	0	1	0	1	0	1
Intra prediction mode	60	61	62	63	64	65	66
											Vertical direction transformation set	0	1	0	1	0	1	0
Horizontal direction transformation set	0	1	0	1	0	1	0

In table 5, the numbers of the vertical transform set and the horizontal transform set to be applied to the horizontal direction of the residual signal according to the intra prediction mode of the target block are shown.

As illustrated in table 5, a transform set to be applied to the horizontal direction and the vertical direction may be predefined according to the intra prediction mode of the target block. The encoding apparatus 100 may perform transformation and inverse transformation on the residual signal using the transformation included in the transformation set corresponding to the intra prediction mode of the target block. Further, the decoding apparatus 200 may perform inverse transformation on the residual signal using the transformation included in the transformation set corresponding to the intra prediction mode of the target block.

In the transform and inverse transform, as illustrated in table 3, table 4, and table 5, a transform set to be applied to a residual signal may be determined and may not be signaled. The transformation indication information may be signaled from the encoding apparatus 100 to the decoding apparatus 200. The transformation indication information may be information indicating which one of a plurality of transformation candidates included in a transformation set to be applied to the residual signal is used.

For example, when the size of the target block is 64 × 64 or less, transform sets each having three transforms may be configured according to the intra prediction mode. The optimal transformation method may be selected from a total of nine multi-transformation methods resulting from a combination of three transformations in the horizontal direction and three transformations in the vertical direction. By such an optimal transformation method, a residual signal may be encoded and/or decoded, and thus encoding efficiency may be improved.

Here, the information indicating which one of a plurality of transforms belonging to each transform set has been used for at least one of a vertical transform and a horizontal transform may be entropy-encoded and/or entropy-decoded. Here, truncated unary binarization may be used to encode and/or decode such information.

As described above, a method using various transforms may be applied to a residual signal generated via intra prediction or inter prediction.

The transform may include at least one of a first transform and a secondary transform. The transform coefficient may be generated by performing a first transform on the residual signal, and the secondary transform coefficient may be generated by performing a secondary transform on the transform coefficient.

The first transformation may be referred to as the "primary transformation". Further, the first transformation may also be referred to as an "adaptive multi-transformation (AMT) scheme". As described above, the AMT may represent applying different transforms to respective 1D directions (i.e., vertical and horizontal directions).

The secondary transform may be a transform for increasing the energy concentration of transform coefficients generated by the first transform. Similar to the first transform, the secondary transform may be a separable transform or a non-separable transform. Such an inseparable transform may be an inseparable secondary transform (NSST).

The first transformation may be performed using at least one of a predefined plurality of transformation methods. For example, the predefined plurality of transform methods may include Discrete Cosine Transform (DCT), Discrete Sine Transform (DST), Karhunen-Loeve transform (KLT), and the like.

Further, the first transform may be a transform having various types according to a kernel function defining a Discrete Cosine Transform (DCT) or a Discrete Sine Transform (DST).

For example, the first transform may include transforms such as DCT-2, DCT-5, DCT-7, DST-1, DST-8, and DCT-8, according to the transform kernel presented in Table 6 below. In table 6 below, various transform types and transform kernels for Multiple Transform Selection (MTS) are illustrated.

MTS may refer to the selection of a combination of one or more DCT and/or DST kernels to transform the residual signal in the horizontal and/or vertical directions.

TABLE 6

In Table 6, i and j may be integer values equal to or greater than 0 and less than or equal to N-1.

A secondary transform may be performed on transform coefficients generated by performing the first transform.

As in the first transformation, a set of transformations may also be defined in the secondary transformation. The method for deriving and/or determining the above-described set of transforms may be applied not only to the first transform but also to the secondary transform.

The first transform and the secondary transform may be determined for a particular target.

For example, the first transform and the secondary transform may be applied to signal components corresponding to one or more of a luminance (luma) component and a chrominance (chroma) component. Whether to apply the first transform and/or the secondary transform may be determined according to at least one of encoding parameters for the target block and/or the neighboring blocks. For example, whether to apply the first transform and/or the secondary transform may be determined according to the size and/or shape of the target block.

In the encoding apparatus 100 and the decoding apparatus 200, transformation information indicating a transformation method to be used for a target may be derived by using the designation information.

For example, the transformation information may include transformation indices to be used for the primary transformation and/or the secondary transformation. Optionally, the transformation information may indicate that the primary transformation and/or the secondary transformation is not used.

For example, when the primary transform and the secondary transform are targeted to a target block, a transform method to be applied to the primary transform and/or the secondary transform indicated by the transform information may be determined according to at least one of encoding parameters for the target block and/or blocks adjacent to the target block.

Alternatively, transformation information indicating a transformation method for a specific object may be signaled from the encoding apparatus 100 to the decoding apparatus 200.

For example, whether to use the primary transform, an index indicating the primary transform, whether to use the secondary transform, and an index indicating the secondary transform may be derived as transform information by the decoding apparatus 200 for a single CU. Optionally, for a single CU, transformation information may be signaled indicating: whether to use a primary transformation, an index indicating a primary transformation, whether to use a secondary transformation, and an index indicating a secondary transformation.

The quantized transform coefficients (i.e., quantized levels) may be generated by performing quantization on a result generated by performing the first transform and/or the secondary transform or performing quantization on the residual signal.

Fig. 13 illustrates a diagonal scan according to an example.

Fig. 14 shows a horizontal scan according to an example.

Fig. 15 shows a vertical scan according to an example.

The quantized transform coefficients may be scanned via at least one of a (top right) diagonal scan, a vertical scan, and a horizontal scan according to at least one of an intra prediction mode, a block size, and a block shape. The block may be a Transform Unit (TU).

Each scan may be initiated at a particular starting point and may be terminated at a particular ending point.

For example, the quantized transform coefficients may be changed into a 1D vector form by scanning the coefficients of the block using the diagonal scan of fig. 13. Alternatively, the horizontal scan of fig. 14 or the vertical scan of fig. 15 may be used according to the size of the block and/or the intra prediction mode, instead of using the diagonal scan.

The vertical scanning may be an operation of scanning the 2D block type coefficients in the column direction. The horizontal scanning may be an operation of scanning the 2D block type coefficients in a row direction.

In other words, which one of the diagonal scan, the vertical scan, and the horizontal scan is to be used may be determined according to the size of the block and/or the inter prediction mode.

As shown in fig. 13, 14, and 15, the quantized transform coefficients may be scanned in a diagonal direction, a horizontal direction, or a vertical direction.

The quantized transform coefficients may be represented by block shapes. Each block may include a plurality of sub-blocks. Each sub-block may be defined according to a minimum block size or a minimum block shape.

In the scanning, a scanning order according to the type or direction of the scanning may be first applied to the subblocks. Further, a scanning order according to the direction of scanning may be applied to the quantized transform coefficients in each sub-block.

For example, as shown in fig. 13, 14, and 15, when the size of the target block is 8 × 8, the quantized transform coefficient may be generated by the first transform, the secondary transform, and the quantization of the residual signal of the target block. Thus, one of three types of scanning orders may be applied to four 4 × 4 sub-blocks, and the quantized transform coefficients may also be scanned for each 4 × 4 sub-block according to the scanning order.

The encoding apparatus 100 may generate entropy-encoded quantized transform coefficients by performing entropy encoding on the scanned quantized transform coefficients, and may generate a bitstream including the entropy-encoded quantized transform coefficients.

The decoding apparatus 200 may extract entropy-encoded quantized transform coefficients from a bitstream, and may generate the quantized transform coefficients by performing entropy decoding on the entropy-encoded quantized transform coefficients. The quantized transform coefficients may be arranged in the form of 2D blocks via inverse scanning. Here, as a method of the inverse scanning, at least one of upper right diagonal scanning, vertical scanning, and horizontal scanning may be performed.

In the decoding apparatus 200, inverse quantization may be performed on the quantized transform coefficients. The secondary inverse transform may be performed on a result generated by performing inverse quantization according to whether the secondary inverse transform is performed. Further, the first inverse transform may be performed on a result generated by performing the secondary inverse transform according to whether the first inverse transform is to be performed. The reconstructed residual signal may be generated by performing a first inverse transform on a result generated by performing the secondary inverse transform.

For the luminance component reconstructed via intra prediction or inter prediction, inverse mapping with dynamic range may be performed before loop filtering.

The dynamic range may be divided into 16 equal segments and the mapping function of the respective segments may be signaled. Such mapping functions may be signaled at the stripe level or parallel block group level.

An inverse mapping function for performing inverse mapping may be derived based on the mapping function.

Loop filtering, storage of reference pictures, and motion compensation may be performed in the inverse mapped region.

The prediction block generated via inter prediction may be transformed to a mapping region by mapping using a mapping function, and the transformed prediction block may be used to generate a reconstructed block. However, since the intra prediction is performed in the mapping region, the prediction block generated via the intra prediction may be used to generate the reconstructed block without the need for mapping and/or inverse mapping.

For example, when the target block is a residual block of the chrominance component, the residual block may be transformed to the inverse mapping region by scaling the chrominance component of the mapping region.

Whether scaling is available may be signaled at the stripe level or the parallel block group level.

For example, scaling may only be applied to the case where the mapping is available for the luma component and the partitions of the chroma component follow the same tree structure.

Scaling may be performed based on an average of values of samples in a luma prediction block corresponding to a chroma prediction block. Here, when the target block uses inter prediction, the luma prediction block may represent a mapped luma prediction block.

The values required for scaling may be derived by referring to a lookup table using an index of a slice to which an average of sample values of the luma prediction block belongs.

The residual block may be transformed to the inverse mapping region by scaling the residual block using the finally derived value. Thereafter, for the block of the chrominance component, reconstruction, intra prediction, inter prediction, loop filtering, and storage of a reference picture may be performed in the inverse mapping region.

For example, information indicating whether mapping and/or inverse mapping of the luminance component and the chrominance component is available may be signaled by the sequence parameter set.

A prediction block for the target block may be generated based on the block vector. The block vector may indicate a displacement between the target block and the reference block. The reference block may be a block in the target image.

In this way, a prediction mode in which a prediction block is generated by referring to a target image may be referred to as an "Intra Block Copy (IBC) mode".

The IBC mode may be applied to a CU having a specific size. For example, the IBC mode may be applied to an mxn CU. Here, M and N may be less than or equal to 64.

The IBC mode may include a skip mode, a merge mode, an AMVP mode, and the like. In the case of the skip mode or the merge mode, the merge candidate list may be configured and the merge index may be signaled, and thus a single merge candidate may be specified among merge candidates existing in the merge candidate list. The block vector of the specified merging candidate may be used as the block vector of the target block.

In the case of AMVP mode, a differential block vector may be signaled. Furthermore, the prediction block vector may be derived from a left neighboring block and an upper neighboring block of the target block. Further, an index indicating which neighboring block is to be used may be signaled.

The prediction block in the IBC mode may be included in the target CTU or the left CTU, and may be limited to a block within the previous reconstruction region. For example, the value of the block vector may be restricted such that the prediction block of the target block is located in a specific region. The specific region may be a region defined by three 64 × 64 blocks that are encoded and/or decoded before a 64 × 64 block including the target block. Limiting the value of the block vector in this manner, memory consumption and device complexity caused by implementation of the IBC mode can thus be reduced.

Fig. 16 is a configuration diagram of an encoding apparatus according to an embodiment.

The encoding apparatus 1600 may correspond to the encoding apparatus 100 described above.

The encoding apparatus 1600 may include a processing unit 1610, a memory 1630, a User Interface (UI) input device 1650, a UI output device 1660, and a storage 1640 that communicate with each other over a bus 1690. The encoding device 1600 may also include a communication unit 1620 connected to the network 1699.

The processing unit 1610 may be a Central Processing Unit (CPU) or semiconductor device for executing processing instructions stored in the memory 1630 or the storage 1640. The processing unit 1610 may be at least one hardware processor.

The processing unit 1610 may generate and process a signal, data, or information input to the encoding apparatus 1600, output from the encoding apparatus 1600, or used in the encoding apparatus 1600, and may perform checking, comparison, determination, or the like related to the signal, data, or information. In other words, in embodiments, the generation and processing of data or information, as well as the inspection, comparison, and determination related to the data or information, may be performed by the processing unit 1610.

The processing unit 1610 may include an inter prediction unit 110, an intra prediction unit 120, a switch 115, a subtractor 125, a transform unit 130, a quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.

At least some of the inter prediction unit 110, the intra prediction unit 120, the switch 115, the subtractor 125, the transform unit 130, the quantization unit 140, the entropy encoding unit 150, the inverse quantization unit 160, the inverse transform unit 170, the adder 175, the filter unit 180, and the reference picture buffer 190 may be program modules and may communicate with an external device or system. The program modules may be included in the encoding device 1600 in the form of an operating system, application program modules, or other program modules.

The program modules may be physically stored in various types of well-known storage devices. Additionally, at least some of the program modules may also be stored in remote memory storage devices that are capable of communicating with the encoding apparatus 1600.

Program modules may include, but are not limited to, routines, subroutines, programs, objects, components, and data structures for performing functions or operations in accordance with the embodiments or for implementing abstract data types in accordance with the embodiments.

The program modules may be implemented using instructions or code executed by at least one processor of the encoding apparatus 1600.

The processing unit 1610 may execute instructions or code in the inter-prediction unit 110, the intra-prediction unit 120, the switch 115, the subtractor 125, the transform unit 130, the quantization unit 140, the entropy encoding unit 150, the inverse quantization unit 160, the inverse transform unit 170, the adder 175, the filter unit 180, and the reference picture buffer 190.

The memory unit may represent the memory 1630 and/or the memory 1640. Each of memory 1630 and storage 1640 may be any of various types of volatile or non-volatile storage media. For example, the memory 1630 may include at least one of Read Only Memory (ROM)1631 and Random Access Memory (RAM) 1632.

The storage unit may store data or information for the operation of the encoding device 1600. In an embodiment, data or information of the encoding apparatus 1600 may be stored in a storage unit.

For example, the storage unit may store pictures, blocks, lists, motion information, inter prediction information, bitstreams, and the like.

The encoding device 1600 may be implemented in a computer system including a computer-readable storage medium.

The storage medium may store at least one module required for the operation of the encoding apparatus 1600. Memory 1630 may store at least one module and may be configured to cause the at least one module to be executed by processing unit 1610.

Functions related to communication of data or information of the encoding apparatus 1600 may be performed by the communication unit 1620.

For example, the communication unit 1620 may transmit the bit stream to the decoding apparatus 1700 to be described later.

Fig. 17 is a configuration diagram of a decoding apparatus according to an embodiment.

The decoding apparatus 1700 may correspond to the decoding apparatus 200 described above.

The decoding apparatus 1700 may include a processing unit 1710, a memory 1730, a User Interface (UI) input device 1750, a UI output device 1760, and a storage 1740 that communicate with each other through a bus 1790. The decoding apparatus 1700 may further include a communication unit 1720 connected to a network 1799.

The processing unit 1710 may be a Central Processing Unit (CPU) or a semiconductor device for executing processing instructions stored in the memory 1730 or the storage 1740. The processing unit 1710 can be at least one hardware processor.

The processing unit 1710 may generate and process a signal, data, or information input to the decoding apparatus 1700, output from the decoding apparatus 1700, or used in the decoding apparatus 1700, and may perform checking, comparison, determination, or the like related to the signal, data, or information. In other words, in embodiments, the generation and processing of data or information, as well as the checking, comparing, and determining related to the data or information, may be performed by the processing unit 1710.

The processing unit 1710 may include the entropy decoding unit 210, the inverse quantization unit 220, the inverse transform unit 230, the intra prediction unit 240, the inter prediction unit 250, the switch 245, the adder 255, the filter unit 260, and the reference picture buffer 270.

At least some of the entropy decoding unit 210, the inverse quantization unit 220, the inverse transform unit 230, the intra prediction unit 240, the inter prediction unit 250, the adder 255, the switch 245, the filter unit 260, and the reference picture buffer 270 of the decoding apparatus 200 may be program modules and may communicate with an external device or system. The program modules may be included in the decoding apparatus 1700 in the form of an operating system, application program modules, or other program modules.

Program modules may be physically stored in various types of well-known memory devices. Furthermore, at least some of the program modules may also be stored in a remote memory storage device that is capable of communicating with the decoding apparatus 1700.

The program modules may be implemented using instructions or code executed by at least one processor of the decoding apparatus 1700.

Processing unit 1710 may execute instructions or code in entropy decoding unit 210, inverse quantization unit 220, inverse transform unit 230, intra prediction unit 240, inter prediction unit 250, switch 245, adder 255, filter unit 260, and reference picture buffer 270.

The memory unit may represent memory 1730 and/or memory 1740. Memory 1730 and storage 1740 can each be any of a variety of types of volatile or non-volatile storage media. For example, memory 1730 may include at least one of ROM 1731 and RAM 1732.

The storage unit may store data or information for the operation of the decoding apparatus 1700. In an embodiment, data or information of the decoding apparatus 1700 may be stored in a storage unit.

The decoding apparatus 1700 may be implemented in a computer system including a computer-readable storage medium.

The storage medium may store at least one module required for the operation of the decoding apparatus 1700. The memory 1730 may store at least one module and may be configured to cause the at least one module to be executed by the processing unit 1710.

Functions related to communication of data or information of the decoding apparatus 1700 can be performed by the communication unit 1720.

For example, the communication unit 1720 may receive a bitstream from the encoding device 1600.

Signaling information for image compression

The image compression technique may be a technique for performing encoding on an input image in consideration of statistical characteristics contained in the input image.

The image compression techniques may include 1) predictive coding techniques for removing temporal and spatial redundancies of the input image, 2) perceptual-vision based transform coding techniques, 3) quantization techniques, 4) entropy coding techniques, 5) filtering techniques for enhancing prediction efficiency, and the like.

The encoding apparatus 100 may receive picture unit information from an original video image to perform encoding. Here, an original image as input information may be referred to as a coded picture.

The predictive coding technique may be a technique for predicting information using: 1) spatial similarity between intra pictures of a target picture, which is a target of encoding/decoding, and 2) temporal similarity between the target picture and a reference picture. The reference picture may be a picture reconstructed prior to encoding/decoding of the target picture. Here, the former case may be referred to as intra prediction, and the latter case may be referred to as inter prediction.

Video image compression techniques may be based on the following principles: the size of the image data is reduced by removing redundant information from the image information.

Video image compression techniques may provide: 1) inter prediction for predicting image information by deriving redundant information between image frames and using the derived information to predict the image information so as to remove the redundant image information on a time axis; and 2) intra prediction for predicting the image signal by deriving redundant information in the image frame and using the derived information to predict the image signal so as to remove redundant image information in space.

The image compression may divide an image in units of a block of a certain size and perform prediction with respect to the block units in order to improve robustness against errors and more efficiently use memory. Here, the target block (or the current block) may be a block that is a target to which current prediction is to be performed in video compression and decompression processing.

Prediction of image information in the image compression technique may perform prediction on pixels in a target block by various methods, such as an intra prediction method using pixels in blocks adjacent to the target block and an inter prediction method using information on an image previously reconstructed before decoding of the target block.

In the image compression process, there is a possibility that: regions having exactly the same image information as the target block will not exist temporally and spatially. Accordingly, a prediction error may occur in the prediction of the image signal, and encoding and decoding of the target block may be performed using residual information corresponding to the prediction error.

The encoding apparatus 100 may transmit prediction information determined based on the most effective prediction method and residual information generated after prediction has been performed to the decoding apparatus 200. Here, the prediction information may be information for specifying a prediction method for the target block. The decoding apparatus 200 may receive the prediction information and the residual information transmitted from the encoding apparatus 100, and may perform decoding on image information using the prediction information and the residual information.

Therefore, during the process of compressing image information, it is beneficial from the viewpoint of efficiency of image compression to minimize the amount of residual information to be transmitted to the decoding apparatus 200 while also minimizing the amount of prediction information to be transmitted to the decoding apparatus 200.

Intra prediction

Reference is made back to fig. 7. Fig. 7 is a diagram for explaining an embodiment of an intra prediction process.

As described above with reference to fig. 7, in intra prediction, prediction of image information for pixels in a target block may be performed using pixels in neighboring blocks adjacent to the target block.

In the intra prediction, the encoding apparatus 100 may derive the encoding efficiencies of the plurality of prediction methods by trying the plurality of prediction methods based on pixels in neighboring blocks in order to minimize the amount of residual information, and may select a prediction method having the best encoding efficiency as the encoding method.

As described above with reference to fig. 7, in the intra prediction, prediction in the DC mode, prediction in the planar mode, prediction in the directional mode, and the like may be used, and image information of pixels in the target block may be predicted based on pixels adjacent to the target block.

The prediction scheme shown in fig. 7 may be an example of a prediction method according to a directional mode of intra prediction. For prediction in DC mode, the average of pixels adjacent to the target block may be used. For prediction in the planar mode, prediction of image information for pixels in a target block may be performed by performing a series of operations using values of pixels adjacent to the target block.

The intra prediction mode determined by the encoding apparatus 100 may be signaled to the decoding apparatus 200. In the signaling operation, a plurality of bits of image information may be required in order to represent various prediction modes.

In image compression, to represent N different values, Ceiling (log) is required₂N) bits or more of digital information. Here, Ceiling (log)₂N) can indicate log₂The smallest integer of the N or more integers. For example, a minimum of 6 bits of digital information may be required to represent 64 different numbers. A minimum of 5 bits of digital information may be required to represent 30 different numbers.

Most Probable Mode (MPM)

In intra prediction for image compression, as a method for reducing the amount of data required to represent an intra prediction mode, a Most Probable Mode (MPM) may be used.

In the MPM, an MPM list including MPM candidates may be configured using intra prediction modes of blocks adjacent to a target block. Each MPM candidate may be an intra prediction mode.

When an MPM candidate that is the same as an intra prediction mode used in intra prediction for the target block exists among the MPM candidates, an MPM index for specifying an MPM candidate in the MPM list may be signaled.

The respective MPM candidates may be 1) intra prediction modes of blocks neighboring the target block, and 2) intra prediction modes determined through a series of operations using the intra prediction modes of the neighboring blocks. Furthermore, 3) when there are no available neighboring blocks or available intra prediction modes of neighboring blocks, the predefined intra prediction mode may be used as an MPM candidate to populate the MPM list.

In general, the number of MPM candidates in the MPM list may be less than the total number of intra prediction modes. Therefore, the information for representing the MPM index may require a smaller number of representation bits than the information for representing all intra prediction modes. Compression can be made more efficient because a smaller number of representation bits are used.

In the encoding apparatus 100 and the decoding apparatus 200, which provide intra prediction using MPM, an MPM flag and an MPM index may be signaled.

The MPM flag may be information indicating whether an MPM candidate will be used when predicting and reconstructing the target block using intra prediction.

When there is an MPM candidate that is the same as the intra prediction mode used in the intra prediction for the target block among the MPM candidates in the MPM list, the MPM index may be an index of the MPM candidate in the MPM list.

As described above, the MPM may be a simple and clear signaling compression method that may be used most fundamentally, but is not limited to a specific intra prediction method, a block partition method, and the like.

After the MPM list has been configured, when encoding/decoding in the intra prediction mode using the MPM is not performed, the MPM flag may be set to "0".

When the MPM flag is 0, a method for performing encoding/decoding in the remaining intra prediction modes except for the intra prediction mode in the MPM list may be used. By this method, the number of representation bits indicating the intra prediction mode can be reduced.

In an embodiment, in index #0 of the MPM list, an intra prediction mode, such as a planar mode most frequently used in intra prediction, may be fixedly arranged. When the plane mode is fixedly located at index #0 of the MPM list, an operation of signaling MPM index #0 may be implemented in the same form as a non-plane (not plane) flag. That is, the non-planar markers may be signaled separately from the signaling of the MPM markers and/or MPM indices.

The non-plane flag may indicate whether another intra prediction mode other than the plane mode is to be used as the intra prediction mode for the target block.

For example, the operation of signaling the MPM index may be additionally performed only when the value of the signaled MPM flag is 1 and the value of the signaled non-planar flag is 1.

For example, when the value of the non-plane flag is 0, the MPM index may not be additionally signaled. Here, since the value of the non-plane flag is 0, the plane mode may be determined as the intra prediction mode for the target block. In other words, since the value of the non-plane flag is 0, the value of the MPM index may be set to 0.

The image information may be represented by digital information such as 1 and 0. In the image information, values 1 and 0 may be used as values for identifying whether or not the condition in the condition sentence is satisfied, and the

values

1 and 0 may indicate "true" and "false", respectively.

In the description of the embodiment, pieces of

digital information

1 and 0 may be regarded as corresponding to "true" and "false", respectively. In other words, pieces of

digital information

1 and 0 may correspond to "true" and "false", respectively. Alternatively, on the other hand, a 1 may correspond to "false" and a 0 may correspond to "true".

In various methods described in the embodiments, the flag and the mode for a specific method may be information indicating whether the specific method will be used.

For example, a case where the flag or pattern for the particular method is true may indicate that the particular method is to be used, and a case where the flag or pattern for the particular method is false may indicate that the particular method is not to be used.

Alternatively, conversely, a case where the flag or pattern for the particular method is true may indicate that the particular method is not to be used, and a case where the flag or pattern for the particular method is false may indicate that the particular method is to be used.

Alternatively, in order to indicate whether the specific method will be used, a predefined specific value or a value derived using a predefined method may be used in addition to the values "true" and "false".

Intra-frame sub-partition (ISP)

Fig. 18 illustrates an ISP for partitioning a target block into two sub-blocks according to an example.

Fig. 19 illustrates an ISP for partitioning a target block into four sub-blocks according to an example.

Fig. 18 and 19 illustrate an example of execution of an ISP, which is one of the intra prediction methods.

In the Intra prediction, as shown in fig. 18 and 19, a block may be divided into smaller blocks by Intra Sub-partition or Intra Sub-Partitioning (ISP), and compression efficiency with respect to image information may be improved by performing prediction, transformation, and the like on the smaller partition block unit.

In the encoding apparatus 100 and the decoding apparatus 200 providing an intra prediction method such as an ISP, an ISP flag and an ISP mode may be additionally signaled.

The ISP flag may indicate whether the ISP is to be used.

The ISP mode may indicate the type of ISP.

For example, the ISP mode may specify the partition direction for the target block. The ISP mode may indicate one of a horizontal mode and a vertical mode. The horizontal mode may be a mode in which horizontal partitions are applied to the target block. The vertical mode may be a mode in which vertical partitioning is applied to the target block.

Hereinafter, ISP signaling may be signaling of information related to an ISP. For example, the ISP signaling may be signaling of ISP identity and ISP mode.

The information related to the ISP may include an ISP logo and an ISP mode. The information related to the ISP may also include the number of sub-partitions (ISPs) within the frame. The number of ISPs may indicate the number of sub-blocks generated from the partition of the target block. The number of ISPs may be signaled from the encoding apparatus 100, and may be derived by the encoding apparatus 100 and the decoding apparatus 200 in the same manner based on the specific encoding parameters illustrated in the above embodiments.

The encoding parameter may indicate at least one of a width and a height of a block, a maximum/minimum value of the width/height, a sum of the width and the height, a number of pixels belonging to the block, a block shape, a component type, a position/range of a reference pixel, a type (e.g., whether an intra prediction mode is a directional mode or whether an intra prediction mode is a predefined default mode) or an angle of an intra prediction mode, information on whether a transform is skipped, a transform type, and the like. Here, the block may be a target block (i.e., at least one of a prediction block and a transform block) or a block adjacent to the target block.

As shown in fig. 18 and 19, when an ISP is used, a target block may be partitioned into N sub-blocks. Here, N may be an integer of 2 or more.

The target block may have a size of W × H. The width of the target block may be W and its height may be H. Here, the width may be the number of horizontal pixels. The height may be the number of vertical pixels. W may be an integer of 1 or greater. H may be an integer of 1 or greater.

As shown in fig. 18, the target block may be vertically halved and partitioned into two sub-blocks each having a size of (W/2) × H. Alternatively, the target block may be horizontally bisected and partitioned into two sub-blocks each having a size of W × (H/2).

As shown in fig. 19, the target block may be vertically quartered and may be partitioned into four sub-blocks all of which have a size of (W/4) × H. Alternatively, the target block may be horizontally quartered and partitioned into four sub-blocks all having a size of W × (H/4).

The shape of the partition of the target block may be determined or limited according to the size of the target block.

For example, when the size of the target block is 4 × 4, partitioning of the target block into sub-blocks may not be performed.

For example, as shown in fig. 18, when the size of the target block is 4 × 8 or 8 × 4, the target block may be partitioned into two sub-blocks.

For example, as shown in fig. 19, when the size of the target block does not correspond to the size exemplified above (i.e., when the size of the target block is equal to or greater than a predefined size (such as 8 × 8)), the target block may be partitioned into four sub-blocks.

In intra prediction using an ISP, an intra prediction mode may be selected (for a target block) before the target block is partitioned. Accordingly, the same intra prediction mode (determined for the target block) may be commonly applied to the plurality of sub blocks generated from the partition, and the plurality of sub blocks generated from the partition may be encoded/decoded using the same intra prediction mode. Further, the information indicating the intra prediction mode may be signaled only once.

Horizontal partitioning may be an operation that partitions a target block into sub-blocks that are all W H/4 or W H/2 in size. That is, the partition direction of the horizontal partition may be horizontal. Vertical partitioning may be an operation that partitions a target block into sub-blocks that are all W/4 XH or W/2 XH in size. That is, the partition direction of the vertical partition may be vertical.

When the target block is partitioned into one or more sub-blocks by the ISP, encoding/decoding may be performed on each sub-block. The encoding of each sub-block may include at least one of prediction, transformation, quantization, inverse transformation, and reconstruction of the corresponding sub-block. The decoding of each sub-block may include at least one of inverse quantization, inverse transformation, prediction, and reconstruction of the corresponding sub-block. In other words, a subblock may be a unit to which a process such as prediction, transformation, quantization, inverse transformation, and reconstruction is to be applied.

By dividing the unit of encoding/decoding, the accuracy of prediction and the like can be improved, and the performance of compression can be enhanced.

Multiple Reference Line (MRL)

Reference is made back to fig. 8. Fig. 8 is a diagram for explaining reference samples used in an intra prediction process.

Fig. 8 illustrates MRL intra prediction. In fig. 8, the square block may be a target block. The slices above and to the left of the target block may be reference regions adjacent to the target block.

In the intra prediction, as shown in fig. 8, pixels in a neighboring area adjacent to a target block may be identified by several lines for prediction with respect to the target block, and the several lines may be used as information to be referred to for prediction. Pixels on one of the lines may be selected as reference pixels.

In the encoding apparatus 100 and the decoding apparatus 200 including the MRL intra prediction method, information related to MRL may be additionally signaled.

The information related to the MRL may include 1) an MRL flag indicating whether the MRL is to be used, and 2) an MRL index. The MRL index may indicate a reference line to be used for prediction among the plurality of reference lines MRL. For example, the MRL index may be an integer of 0 or greater. The MRL index value of 0 may indicate that a reference line 0 closest to (i.e., adjacent to) the target block among the plurality of reference lines is to be used for prediction of the target block. In the "reference line n" shown in fig. 8, "n" may be an index of the reference line.

In intra prediction using MRL, an intra prediction mode may be configured for each reference line (without limitation), and information related to the configured intra prediction mode may be signaled. In order to minimize the occurrence of a large amount of information related to an intra prediction mode due to such an unlimited configuration method, the intra prediction mode may be limited based on the MRL index.

In an embodiment, when an MRL index of 1 or more is used (i.e., when an additional reference line other than reference line 0 adjacent to the target block is used), 1) the non-planar mode and 2) the MPM candidates in the MPM list may have to be used as the intra prediction mode for the target block. Accordingly, in intra prediction using an MRL index of 1 or more, the intra prediction mode for the target block can be configured by necessarily utilizing the MPM. Due to this limitation, when the value of the MRL index is 1 or more, the MPM flag may not be signaled separately, and the value of the MPM flag may be set to 1 (without signaling).

In an embodiment, the ISP may not be used when an MRL index of 1 or more is used (i.e., when an additional reference line other than reference line 0 adjacent to the target block is used). Accordingly, when the value of the MRL index is 1 or more, the operation of signaling the ISP flag and the ISP mode may be skipped. Further, when the value of the MRL index is 1 or more, the value of the ISP flag may be set to 0.

Matrix weighted intra prediction (MIP)

Fig. 20 shows a MIP according to an example.

MIP may extract samples from tiles neighboring the target tile, and MIP samples may be configured by calculating statistics of the extracted samples. For example, the statistical value may be an average value.

The predicted samples may be configured by operation using a predefined matrix for MIP samples. The predicted samples may fill in specific locations in the target block. The prediction block may be generated by interpolating prediction samples filling the specific location.

In fig. 20, rectangles indicated by bold edges in portions below and to the left of "3. interpolation" may be prediction blocks filled with MIP samples. Rectangles in the prediction block may indicate pixels. The dark rectangles may be pixels filled with predicted samples. As shown in fig. 20, the predicted sampling points may be arranged at the positions of coordinates (2n +1 ). Here, x may be an integer of 0 or more, and y may be an integer of 0 or more. The coordinates of the uppermost leftmost pixel in the prediction block may be (0, 0).

In fig. 20, rectangles indicated by bold edges in portions below and to the right of the "3. interpolation" may be prediction blocks to which the interpolation is applied. As described above, a pixel having an x-coordinate (2n) or a y-coordinate (2n) can also be filled with a value (generated by interpolation) by interpolation.

In the encoding apparatus 100 and the decoding apparatus 200 providing intra prediction using MIP, a MIP flag and a MIP mode may be additionally signaled.

The MIP flag may indicate whether MIP is to be used.

The MIP mode may indicate a matrix for MIP. In other words, the MIP mode may be matrix selection information. The matrix for MIP may comprise a plurality of matrices. The matrix for MIP may also be selected based on the encoding parameters for the target block. The matrix for MIP may be selected based on the MIP mode and the encoding parameters for the target block. Here, the encoding parameter may be a combination of one or more of the above-described encoding parameters. For combination, logical operators (e.g., logical OR operators, logical AND operators, exclusive OR (xor) operators, NOT (NOT) operators, etc.), arithmetic operators (e.g., addition (+) operators, multiplication (— operators, subtraction (-) operators, absolute value operators, etc.), comparison operators, etc. may be used.

Hereinafter, the MIP signaling may be signaling of MIP-related information. The information related to MIP may include a MIP flag and a MIP mode.

Available intra-prediction modes and signaling for intra-prediction modes

Fig. 21 illustrates available intra prediction modes depending on whether sub-partitions are to be applied or not, according to an example.

An image may be partitioned into block units, and encoding/decoding such as prediction may be performed on the partitioned blocks. Further, even within a block, a corresponding block may be partitioned into units of sub-blocks or units of a region, and encoding/decoding such as prediction may be performed on the partitioned sub-blocks or partitioned regions.

A sub-partition may indicate an operation to partition a block into units of sub-blocks or units of a region.

The sub-partition mode for a block may indicate a mode in which the block is partitioned into sub-blocks and decoding, such as prediction, is performed on each partitioned sub-block. For example, the sub-partition mode may be an ISP mode. The child partition identity may be an ISP identity.

In an embodiment, at least one of an intra prediction method and an intra prediction mode may be set for a target block, and the intra prediction method and/or the intra prediction mode set for the target block may be commonly applied to partitioned sub blocks or partitioned areas.

Alternatively, in an embodiment, at least one of an intra prediction method and an intra prediction mode may be set for the sub-block or the partitioned area. In other words, the intra prediction methods and/or intra prediction modes of two or more sub-blocks or two or more regions in the target block may be different from each other.

In the following embodiments, the ISP flag may be a sub-partition flag, and in the description of ISP and ISP flag, the ISP may be replaced with a sub-partition, and the ISP flag may be replaced with a sub-partition flag.

The sub-partition flag may be signaled from the encoding apparatus 100 to the decoding apparatus 1200.

The sub-partition flag may indicate whether sub-partitioning is to be applied to the target block.

When the sub-partition flag is 1, the sub-partition may be applied to the target block. When the sub-partition flag is 0, the sub-partition may not be applied to the target block.

In fig. 21, when the sub-partition mode is used (i.e., when the target block is partitioned), the intra prediction modes indicated in the above section may indicate available intra prediction modes. When the sub-partition mode is not used (i.e., when the target block is not partitioned), the intra prediction mode indicated in the lower portion may indicate an available intra prediction mode.

Here, the expression "a specific intra prediction mode is available" may have the same meaning as the expression "a specific intra prediction mode may be applied to intra prediction (for a block)". Also, the expression "a specific intra prediction mode is available" may have the same meaning as the expression "a specific intra prediction mode may be applied to intra prediction (for a block)". When a "specific intra prediction mode is available for a block," it may be determined whether the specific intra prediction mode is to be used for the block based on information indicating an intra prediction mode (for the block).

Furthermore, the expression "the specific intra prediction mode is not available" may have the same meaning as the expression "the specific intra prediction mode cannot be used for intra prediction (for a block)". Also, the expression "a specific intra prediction mode is not available" may have the same meaning as the expression "a specific intra prediction mode is not applicable to a block".

When a specific intra prediction mode is not available for a block, information indicating whether the specific intra prediction mode is to be used may not be signaled.

Further, in an operation of signaling information for specifying an intra prediction mode (to be used for a block), the information may have a value that does not include a value indicating that a specific intra prediction mode is unavailable. That is, the information for specifying the intra prediction mode may have a value indicating one of the available intra prediction modes. Accordingly, as the number of intra prediction modes that are not available under certain conditions increases, the number of bits required to signal information for specifying the intra prediction mode may be reduced.

In fig. 21 and subsequent figures, "PLANAR _ MODE" may indicate a PLANAR MODE. "DC _ MODE" may indicate a DC MODE. "angle _ MODE _ N" may indicate an nth angle MODE (i.e., a direction MODE). N may be an integer of 0 or greater.

Here, N may indicate the number of directional intra prediction modes instead of the number of the above-described intra prediction mode described above with reference to fig. 7. The sequence number may start with 0. For example, "ANGULAR _ MODE _ 0" may indicate the first directional intra prediction MODE among the directional intra prediction MODEs, instead of the intra prediction MODE with number 0. "ANGULAR _ MODE _ 1" may indicate a second one of the directional intra prediction MODEs. "ANGULAR _ MODE _ N-1" may indicate an Nth directional intra prediction MODE among the directional intra prediction MODEs. "ANGULAR _ MODE _ N" may indicate the (N + 1) th directional intra prediction MODE among the directional intra prediction MODEs, instead of the intra prediction MODE having the number N.

In an embodiment, as shown in fig. 21, the intra prediction modes available in the sub-partition mode may be all intra prediction modes. For example, the intra prediction mode available for the target block may be equally available for the sub-blocks.

Here, the case where a specific intra prediction mode is available for a block may mean that the specific intra prediction mode may be used for prediction of the block. The unavailable intra prediction mode may not be used for prediction of the block. Information for specifying an intra prediction mode to be used for intra prediction of a block among intra prediction modes available for the block may be signaled from the encoding apparatus 100 to the decoding apparatus 200.

In order to represent multiple available intra prediction modes, multiple representation bits may be required. Accordingly, signaling information specifying an intra-prediction mode to be used for prediction of a block from among a plurality of available intra-prediction modes may result in lower efficiency than prediction.

Thus, in the sub-partition mode, certain intra prediction modes exhibiting relatively low prediction performance may be restricted such that they are unavailable. For example, the specific intra prediction modes exhibiting relatively low prediction performance may be a planar mode, a DC mode, and an odd-numbered directional mode. The odd numbered directional pattern may be an nth angular pattern, wherein the value of N is an odd number.

When this restriction is applied, the number of bits to be signaled to indicate the intra prediction mode can be reduced while causing slight deterioration of the prediction performance, and thus a more efficient signaling structure can be realized.

In an example, in the case where the plane mode is not available in the sub-partition mode, when the sub-partition flag is 1, the plane mode is never used, and thus an operation of signaling the non-plane flag may be skipped in the encoding apparatus 100 and the decoding apparatus 200, and the decoding apparatus 200 may derive the non-plane flag as 1.

For example, when a planar mode is not available in the ISP mode and a non-planar flag is signaled before information related to the ISP is signaled, the operation of signaling the ISP flag may be skipped when the value of the non-planar flag is 0, since a non-planar flag value of 0 means that the value of the ISP flag is 0.

In intra prediction, planar modes may generally have a higher probability of occurrence than other intra prediction modes. Therefore, compared to the case where the non-plane flag is additionally signaled after the MPM list is configured to include the plane mode, a method for preferentially signaling the non-plane flag and setting the intra prediction mode for the target block to the plane mode when the value of the non-plane flag is 0 may be used.

When the value of the non-plane flag is 0, an operation of signaling both the MPM flag and the MPM index for deriving the intra prediction mode may be skipped. Further, when the value of the MRL index is greater than 0, the planar mode is not available, and when the value of the non-planar flag that is preferentially signaled is 0, the MRL index may be set to 0 (without being signaled). Further, information indicating whether additional intra prediction in which a plane mode is not available or additional intra prediction modes in which a plane mode is not available will be used may be set to 0 (without signaling).

By utilizing these characteristics, a method can be used in which: the plane mode is restricted such that the plane mode is not available in the ISP having low plane mode efficiency, and the ISP flag is set to 0 when the value of the non-plane flag is 0. When such a limitation and method is used, the planar mode is not available, and thus a loss may occur due to deterioration of prediction accuracy. On the other hand, when such a restriction and method are used, an operation of signaling 1 bit corresponding to the ISP flag and an operation of signaling an additional bit related to the ISP mode may be skipped, and thus an advantage may be obtained from the viewpoint of compression efficiency.

In an embodiment, when the value of the MRL index is equal to or greater than 1, MPM may always be used. Accordingly, when the value of the MRL index is equal to or greater than 1, the MPM flag may not be separately signaled. Further, when the value of the MRL index is equal to or greater than 1, the planar mode is not available, and thus the non-planar flag may not be separately signaled and may be derived as 1.

In an embodiment, the intra prediction mode used in MIP may be different from the existing directional mode. Further, intra prediction used in MIP may be different from intra prediction of other intra prediction methods in the overall intra prediction process including the configuration of MPM and the like. Thus, when MIP is used, the MIP independent MPM flags and non-planar flags may not be signaled separately.

In an embodiment, the MPM flag may always be signaled regardless of whether ISP related information is signaled. In addition, when the value of the MPM flag is 1, the non-planar flag may be always signaled.

In embodiments, there may be dependencies between the MRL index and the ISP flag, and there may also be dependencies between the MRL flag, the MPM flag, and the non-flat flag. Accordingly, based on the dependency between the intra prediction methods, signaling of the intra prediction methods may be integrated and adjusted, and unnecessary signaling may be skipped.

Fig. 22 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method according to an embodiment.

In the flow diagrams of fig. 22 and subsequent figures, each rectangle may represent a step of the process. For example, the processing unit may perform the step of writing in each rectangle.

In the flowcharts of fig. 22 and the subsequent drawings, each arrow indicates that the process of the step indicated by the arrow is performed after the process of the step starting from the corresponding arrow. That is, each arrow may indicate a sequence of steps.

In the flow chart of fig. 22 and subsequent figures, each diamond indicates a comparison step and a branching step based on the result of the comparison. For example, the processing unit may perform the step of writing in each diamond. When the result of the comparison indicated by the diamond indicates true (i.e., "yes"), steps beginning with the diamond and indicated by the arrow labeled "yes" may then be performed. When the result of the comparison indicated by the diamond indicates false (i.e., "no"), the steps beginning with the diamond and indicated by the arrow labeled "no" may then be performed.

At the steps of the flow charts of fig. 22 and subsequent figures, "signaled" may mean writing and reading information transmitted from the encoding apparatus 1600 to the decoding apparatus 1700 through the bitstream.

Further, at the steps of the flowcharts of fig. 22 and subsequent figures, "signaled" may indicate that information as a target of signaling is added to a bitstream by the processing unit 1610 of the encoding apparatus 1600, or the communication unit 1620 of the encoding apparatus 1600 transmits the information as the target of signaling to the decoding apparatus 1700.

Further, in the steps in the flowcharts of fig. 22 and subsequent figures, "signaled" may indicate that the processing unit 1710 of the decoding apparatus 1700 acquires information as a target of signaling from a bitstream, or that the communication unit 1720 of the decoding apparatus 1700 receives information as a target of signaling from the encoding apparatus 1600.

In the flowcharts of fig. 22 and subsequent figures, "start" may indicate a starting point in a (partial) signaling procedure described in the embodiment, and may not indicate a starting point in the entire signaling procedure related to intra prediction for a target block. In the flowcharts of fig. 22 and subsequent figures, "end" may indicate an end point in a (part of) signaling procedure described in the embodiment, and may not indicate an end point in the entire signaling procedure related to intra prediction for a target block.

At step 2210, a MIP flag may be signaled.

At step 2215, it may be checked whether the value of the MIP flag is 1.

At step 2220, MIP mode can be signaled.

At step 2225, the MRL index may be signaled.

At step 2230, it may be checked whether the value of the MRL index is greater than 0.

At step 2235, the value of the MPM flag may be set to 1.

At step 2240, the ISP flag may be signaled.

At step 2245, it may be checked whether the value of the ISP flag is 1.

At step 2250, the ISP mode may be signaled.

At step 2255, an MPM flag may be signaled.

In step 2260, it may be checked whether the value of the MPM flag is 1.

In step 2265, the intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The signaled intra prediction mode may be signaled using Truncated Binary Coding (TBC). The TBC may be a method for selecting an intra prediction mode for the block from the remaining modes. The remaining modes may be intra prediction modes of the intra prediction modes that do not include MPM candidates in the MPM list.

At step 2270, it may be checked whether the value of the MRL index is greater than 0.

At step 2280, a non-planar token may be signaled.

In step 2285, it may be checked whether the value of the non-planar flag is 1.

At step 2290, the MPM index may be signaled.

In step 2295, reconstruction (or setting) of the intra prediction mode may be performed. That is, based on the signaled information, the intra prediction mode for the target block may be determined.

For example, when step 2295 is performed after determining that the value of the non-plane flag is not 1, the value of the non-plane flag is 0, and thus the plane mode may be determined as the intra prediction mode.

For example, when step 2295 is performed after the MPM index is signaled, an MPM candidate indicated by the MPM index among the MPM candidates in the MPM list may be determined as the intra prediction mode.

The above-described steps may represent operations for signaling pieces of information related to MIP, MRL index, ISP, MPM, and non-planar flag.

When the MIP flag is signaled in step 2210 and the value of the MIP flag is 1 in step 2215, an operation of signaling the MIP mode may be performed in step 2220 and an operation of signaling pieces of information related to the MRL, the ISP, the MPM, and the non-plane flag may not be performed.

When the value of the MRL index is greater than 0 at step 2270, no operation of signaling the non-planar flag may be performed.

As described above in the foregoing steps, whether the MPM flag and the non-planar flag are to be signaled may vary according to flags and indexes of the ISP, MRL, and MIP. In particular, for non-planar tokens, the case where a non-planar token is always signaled or never signaled may occur depending on the conditions of the token and index based ISP, MRL, and MIP.

In an example, the non-planar flag may be signaled only when the value of the MPM flag is 1. Thus, signaling a non-flat flag may indicate that the value of the MPM flag is 1.

For example, a case where the value of the non-plane flag is 0 may indicate that the intra prediction mode of the target block is the plane mode. Therefore, when the value of the MRL index is greater than 0, the planar mode is not used, and thus if the value of the non-planar flag is 0, the value of the MRL index may be 0. Thus, in this case, the MRL index may be derived as 0, and an operation of signaling the MRL index may be skipped.

Further, as described above, when the planar mode is not available, as in the case of the ISP, the case where the value of the non-planar flag is 0 may indicate that the value of the ISP flag is also 0. Therefore, when the value of the non-planar flag is 0, the ISP flag may be additionally derived as 0, and an operation of signaling the ISP flag may be skipped.

Accordingly, in an example, when an operation of signaling a non-plane flag may be performed at the highest priority and an available intra prediction mode in an ISP is limited, an operation of signaling pieces of information related to the ISP, MRL, and MIP may be skipped according to the non-plane flag and the available intra prediction mode. Such a configuration may be more efficient from a signaling perspective.

Fig. 23 illustrates a syntax structure signaling pieces of information related to an intra prediction method according to an example.

In fig. 23, a syntax structure for signaling pieces of information related to the intra prediction method using MIP, MRL, ISP, and MPM in the embodiment is depicted.

According to the syntax structure shown in fig. 23, in the encoding apparatus 1600 and the decoding apparatus 1700, an operation of signaling the MIP flag (i.e., intra _ MIP _ flag [ x0] [ y0]) can be preferentially performed.

When the value of the MIP flag is 1, an operation of signaling the MIP mode (i.e., intra _ MIP _ mode [ x0] [ y0]) can be performed.

The operation of signaling the MRL index (i.e., intra _ luma _ ref _ idx x0 y 0) may be performed only if the value of the MIP flag is not 1.

When a condition including a condition that the value of the MRL index is 0 is satisfied, an operation of signaling information related to the ISP, i.e., intra _ sub _ aspects _ mode _ flag [ x0] [ y0] and intra _ sub _ aspects _ split _ flag [ x0] [ y0], may be performed.

Next, when the MRL index has a value of 0, an MPM flag (i.e., intra _ luma _ MPM _ flag [ x0] [ y0]) may be signaled.

When the value of the MPM flag is 1, the MRL index may be checked again, and when the value of the MRL index is 0, a non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be signaled.

When the value of the non-flat flag is 1, the MPM index (intra _ luma _ MPM _ idx [ x0] [ y0]) can be signaled.

In fig. 23, as shown in italics, the conditional statement for checking whether the value of the MRL index is 0 may be repeatedly executed a plurality of times. Therefore, the syntax structure shown in fig. 23 can be improved. With such a modification, signaling of an intra prediction mode or the like may be added to the syntax structure shown in fig. 23, or alternatively, some components may be omitted from the syntax structure.

Fig. 24 illustrates a determination of whether other flags and other indices and values of the other flags and other indices are to be signaled according to values of MIP flags according to an example.

In the table of fig. 24, it is shown whether the additional flag and the additional index and the values of the additional flag and the additional index will be signaled for the case where the MIP flag is signaled with the highest priority.

According to the table of fig. 24, when the value of the MIP flag is 1, the operation of signaling the MRL index, the ISP flag, the MPM flag, and the non-plane flag may be skipped.

Conversely, when the value of the MIP flag is 0, the MRL index may always be signaled.

The ISP flag may be conditionally signaled when the value of the MIP flag is 0. That is, when the value of the MRL index is greater than 0, the ISP flag may be set to 0, and an operation of signaling the ISP flag may be skipped. When the value of the MRL index is 0, the ISP flag may be always signaled.

When the value of the MIP flag is 0, the MPM flag may be always signaled.

The non-planar flag may be signaled only when the value of the MPM flag is 1. When the value of the MRL index is greater than 0, the non-planar flag may be derived as 1 and may not be signaled.

In encoding and decoding of an image, MIP is one of various intra prediction methods including MRL, ISP, and the like, and thus the usage ratio of MIP may not be high.

In the signaling structure of fig. 24, the worst case may be a case where all of signaling of the MRL index, signaling of information related to the ISP, signaling of information related to the MPM, and signaling of the non-planar flag are performed. The case where the value of the MIP flag is 0 may correspond to the worst case.

In general, in image encoding and decoding, the probability that the MIP is selected is not high, and thus the case where the value of the MIP is 0 is in most cases compared to the case where the value of the MIP is 1. Since the probability that the MIP value is 0 is high, the probability that the worst case occurs may also be high. Therefore, in the worst case, it is necessary to reduce the number of bits to be signaled.

In subsequent embodiments to be described later, a method for reconfiguring the order and conditions of signaling and configuration of the MPM flag, MRL index, ISP flag, ISP mode, non-planar flag, and the like will be described. In such a reconfiguration, inefficient intra prediction modes may be restricted from being used in a particular intra prediction method, such as an ISP. According to such reconfiguration, 1) the structural problem of performing the repetitive operation on the MRL index described above with reference to fig. 22, 23, and 24 can be solved, and 2) the compression efficiency can be improved.

Intra prediction with respect to sub-partitions-for setting a specific intra prediction mode to not according to the application of sub-partitions Available methods

Fig. 25 illustrates a method for setting a specific intra prediction mode to be unavailable according to an application of a sub-partition according to an embodiment.

At least some of the description made above with reference to fig. 21 may be applied to the embodiment to be described with reference to fig. 25. Duplicate description will be omitted here.

When the number of available intra prediction modes is large, the number of bits signaled from the encoding apparatus 1600 to the decoding apparatus 1700 may increase.

In a sub-partition mode that includes an ISP, there is a strong likelihood that a particular block will be partitioned into smaller blocks. Therefore, when sub-partitions are applied, the availability of all intra-prediction modes may require a large number of bits in order to signal the intra-prediction modes, compared to the prediction performance gains. Therefore, when a sub-partition mode such as an ISP is used, some intra prediction modes may be set to unavailable.

As shown in fig. 25, some specific intra prediction modes may not be available in the sub partition mode.

As shown in fig. 25, a sub-partition flag may be signaled, and when the value of the sub-partition flag is 1, a specific intra prediction mode may be unavailable. In other words, when the value of the sub-partition flag is 1, the specific intra prediction mode may be excluded from the selected target, and the unavailable intra prediction mode may not be considered even in the signaling of the intra prediction mode.

In fig. 25, an intra prediction mode overlapping with a symbol "X" may indicate an intra prediction mode that is unavailable. In other words, in an embodiment, when the value of the child partition flag is 1, PLANAR _ MODE, ANGULAR _ MODE _0, and ANGULAR _ MODE _2 may not be available.

The unavailable intra prediction mode shown in fig. 25 may be an example of an arbitrary indication. The unavailable intra prediction mode may be set in a different manner from the embodiment.

Embodiments are exemplified such that unavailable intra prediction modes are equally set for an intra prediction mode of a luma component block corresponding to luma information and an intra prediction mode for a chroma component block corresponding to chroma information.

In an embodiment, the setting of the unavailable intra prediction mode may be differently applied to the luminance component block and the chrominance component block. Different unavailable intra prediction modes may be set for the luma component block and the chroma component block, respectively.

Fig. 26 illustrates a method for setting a plane mode to be unavailable according to an application of an ISP according to an embodiment.

At least some of the descriptions made above with reference to fig. 21 and 25 may also be applied to the embodiment to be described with reference to fig. 26. Duplicate description will be omitted here.

Fig. 26 illustrates a case where a plane mode is set to be unavailable in a method for setting a specific intra prediction mode to be unavailable when an ISP is used.

As shown in fig. 26, the ISP flag may be signaled, and when the value of the ISP flag is 1, the planar mode may be unavailable.

In fig. 26, a planar mode overlapping with a symbol "X" may be an unavailable intra prediction mode.

Fig. 27 illustrates a method for setting a DC mode to be unavailable according to an application of an ISP according to an embodiment.

At least some of the descriptions made above with reference to fig. 21 and 25 may also be applied to the embodiment to be described with reference to fig. 27. Duplicate description will be omitted here.

Fig. 27 illustrates a case where the DC mode is set to be unavailable in a method for setting a specific intra prediction mode to be unavailable when an ISP is used.

As shown in fig. 27, the ISP flag may be signaled, and when the value of the ISP flag is 1, the DC mode may be unavailable.

In fig. 27, the DC mode overlapping with the symbol "X" may be an unavailable intra prediction mode.

Fig. 28 illustrates a method for setting a non-directional intra prediction mode to be unavailable according to an application of an ISP according to an embodiment.

At least some of the descriptions made above with reference to fig. 21 and 25 may also be applied to the embodiment to be described with reference to fig. 28. Duplicate description will be omitted here.

Fig. 28 illustrates a case where a non-directional intra prediction mode is set to be unavailable in a method for setting a specific intra prediction mode to be unavailable when an ISP is used. The non-directional intra prediction mode may be a non-angular mode. The non-directional intra prediction modes may include a planar mode and a DC mode.

As shown in fig. 28, the ISP flag may be signaled, and when the value of the ISP flag is 1, the planar mode and the DC mode may be unavailable.

In fig. 28, the planar mode and the DC mode overlapping with the symbol "X" may be unavailable intra prediction modes.

Fig. 29 illustrates a method for setting some of directional intra prediction modes specified according to a predefined condition as unavailable according to an application of an ISP according to an embodiment.

At least some of the descriptions made above with reference to fig. 21 and 25 may also be applied to the embodiment to be described with reference to fig. 29. Duplicate description will be omitted here.

Fig. 29 illustrates a case where some directional intra prediction modes selected according to a predefined condition are set as unavailable in a method for setting a specific intra prediction mode as unavailable when an ISP is used.

For example, some directional intra prediction modes selected according to the predefined condition may be 1) intra prediction modes with odd numbers, 2) intra prediction modes with even numbers, 3) wide angle modes, or 4) other intra prediction modes that satisfy the predefined condition.

The wide angle mode may be an intra prediction mode in which the value of an angle in the angle mode falls outside a predefined range.

In fig. 29, an angle mode 0 and an angle mode N-1 overlapping a symbol "X" may be unavailable intra prediction modes.

In fig. 29, the unavailable intra prediction modes (i.e., the angle mode 0 and the angle mode N-1) may be intra prediction modes having numbers satisfying the predefined condition among the directional intra prediction modes.

In an embodiment, the predefined condition may be signaled from the encoding device 1600 to the decoding device 1700. Information indicating the predefined condition may be signaled from the encoding apparatus 1600 to the decoding apparatus 1700. The predefined condition may be equally set by the encoding apparatus 1600 and the decoding apparatus 1700 by the signaled information.

Alternatively, the predefined condition may be included in each of the encoding apparatus 1600 and the decoding apparatus 1700 without separate signaling. In this case, the operation of signaling the predefined condition may be skipped.

As shown in fig. 29, the ISP flag may be signaled, and when the value of the ISP flag is 1, some intra prediction modes selected according to the predefined condition may be unavailable.

Fig. 30 illustrates a method for setting a wide angle mode to be unavailable according to an application of an ISP according to an embodiment.

At least some of the descriptions made above with reference to fig. 21, 25, and 29 may be applied to the embodiment to be described with reference to fig. 29. Duplicate description will be omitted here.

In fig. 30 and subsequent figures, "WIDE _ angle _ MODE _ N" may be the nth WIDE angle MODE. N may be an integer of 0 or greater.

Here, N may indicate the number of wide angle modes instead of the number of intra prediction modes described above with reference to fig. 7. The sequence number may start with 0. For example, "WIDE _ angle _ MODE _ 0" may be the first WIDE angle MODE of the WIDE angle MODEs, instead of the intra prediction MODE with number 0. "WIDE _ angle _ MODE _ 1" may be the second WIDE angle MODE among the WIDE angle MODEs, instead of the intra prediction MODE having the number 1.

The embodiment described with reference to fig. 30 may be one of the methods in the embodiments described with reference to fig. 29. Fig. 30 illustrates a case where a wide angle mode is set to be unavailable in a method for setting a specific intra prediction mode to be unavailable when an ISP is used.

In fig. 30, the wide angle mode 0 and the wide angle mode N-1 overlapping the symbol "X" may be unavailable intra prediction modes.

In an embodiment, the ISP flag may be signaled and when the value of the ISP flag is 1, the wide angle mode may be unavailable. Depending on the state of the ISP, all wide angle modes may be set as unavailable or only some wide angle modes corresponding to some wide angles may be restrictively set as unavailable.

Fig. 31 illustrates a method for setting a directional intra prediction mode having an odd number and a plane mode to be unavailable according to an application of an ISP according to an embodiment.

At least some of the descriptions made above with reference to fig. 21, 25, and 30 may be applied to the embodiment to be described with reference to fig. 29. Duplicate description will be omitted here.

In fig. 30 and subsequent figures, "EVEN _ MODE _ angle _ N" may be the nth EVEN-numbered angle MODE. The even angle pattern may be an angle pattern having an even number. N may be an integer of 0 or greater. "ODD _ MODE _ angle _ N" may be the nth ODD numbered angle MODE. The odd-numbered angular patterns may be angular patterns having odd numbers. N may be an integer of 0 or greater.

Here, N may indicate the order number of an even-numbered angle mode or an odd-numbered angle mode, instead of indicating the number of the above-described intra prediction mode as described above with reference to fig. 7. The sequence number may start with 0. For example, "EVEN _ MODE _ angle _ 0" may be the first EVEN ANGULAR MODE of the EVEN-numbered ANGULAR MODEs, instead of the intra prediction MODE with number 0. "EVEN _ MODE _ angle _ N" may be the (N + 1) th EVEN angle MODE among the EVEN-numbered angle MODEs, instead of the intra prediction MODE having the number 0. For example, "ODD _ MODE _ angle _ 0" may be the first ODD ANGULAR MODE of the ODD numbered ANGULAR MODEs, instead of the intra prediction MODE with number 0. "ODD _ MODE _ angle _ N" may be the (N + 1) th ODD ANGULAR MODE among the ODD-numbered ANGULAR MODEs, instead of the intra prediction MODE having the number 0.

The embodiment described with reference to fig. 31 may be one of the methods in the embodiments described with reference to fig. 29. Fig. 31 illustrates a case where odd-numbered angle modes and plane modes are set to be unavailable in a method for setting a specific intra prediction mode to be unavailable when an ISP is used.

In fig. 31, odd-numbered angular modes and planar modes overlapping with the symbol "X" may indicate an unavailable intra prediction mode.

In an embodiment, the ISP flag may be signaled, and when the value of the ISP flag is 1, the odd-numbered angle mode and the plane mode may be unavailable. Depending on the state of the ISP, all wide angle modes may be set as unavailable or only some wide angle modes corresponding to some wide angles may be restrictively set as unavailable.

The embodiment described with reference to fig. 31 may be a combination of specific conditions present in the embodiment described above with reference to fig. 26 and the embodiment described above with reference to fig. 29.

As described above with reference to fig. 31, the embodiments described above with reference to fig. 25, 26, 27, 28, 29, 30, and 31 may be combined with each other in order to set a specific intra prediction mode as unavailable. In other words, the operation of setting the specific intra prediction mode to be unavailable described above with reference to fig. 25, 26, 27, 28, 29, 30, and 31 may be applied in an overlapping manner.

Further, the conditions presented in the embodiments described above with reference to fig. 25, fig. 26, fig. 27, fig. 28, fig. 29, fig. 30, and fig. 31 may be changed. For example, in the embodiment described above with reference to fig. 31, the odd-numbered angle pattern is set as unavailable, but the embodiment may be changed such that the even-numbered angle pattern or the wide angle pattern is set as unavailable.

Signaling performed when a specific intra prediction mode is set as unavailable according to an application of a sub-partition

Fig. 32 illustrates a signaling method when a specific intra prediction mode is not available in an ISP according to an embodiment.

As described above with reference to fig. 25, a specific intra prediction mode may be set to be unavailable when a sub-partition is applied. The embodiment described with reference to fig. 32 may be a signalling method according to the embodiment described above with reference to fig. 25.

At step 3210, an ISP flag may be signaled.

At step 3220, it may be checked whether the value of the ISP flag is 1.

When the value of the ISP flag is 1, signaling of an intra prediction mode other than a specific intra prediction mode (set to unavailable) may be performed in step 3230.

Here, signaling the intra prediction mode may refer to signaling information related to the intra prediction mode and information related to other prediction methods with respect to the ISP.

The intra prediction mode may include not only a non-directional mode such as a planar mode and a DC mode but also a directional mode such as an angular mode.

The information related to the intra prediction mode may be information required to reconstruct the intra prediction mode for the block, and may include information related to the MPM and information related to the non-MPM.

The information related to the other prediction methods may include flags, indexes, modes, etc. of the other prediction methods. The other prediction methods may include MRL, MIP, and the like.

That is, information required in order to determine an intra prediction mode for a block among the remaining intra prediction modes except for the specific intra prediction mode set to be unavailable may be signaled.

When the value of the ISP flag is not 1, an operation of signaling the intra prediction mode may be performed at step 3240.

That is, information required to determine the intra prediction mode for a block among (all) intra prediction modes may be signaled (no intra prediction mode is set to unavailable).

Fig. 33 illustrates a signaling method when a non-planar label is not used in an ISP according to an embodiment.

The embodiment described with reference to fig. 33 may be one example of the embodiment described with reference to fig. 32. In other words, in the embodiment described with reference to fig. 33, the intra prediction mode set to be unavailable may be a planar mode.

At step 3310, an ISP flag may be signaled.

At step 3320, it may be checked whether the value of the ISP flag is 1.

When the value of the ISP flag is 1, the operation of signaling the non-planar flag may be skipped and the non-planar flag may be derived as 1 in step 3330.

For example, when the value of the ISP flag is 1 and the plane mode is set to be unavailable, if the value of the ISP flag checked in step 3320 is 1, the plane mode is not used. Accordingly, since the plane mode is not used, a non-plane flag indicating whether the plane mode will be used may not be signaled, and the non-plane flag may be derived as "1".

When the value of the ISP flag is not 1, a non-planar flag may be signaled at step 3340 (since planar mode may be used).

That is, unless the plane mode is set to unavailable, a non-plane flag required to determine whether the plane mode will be used may be signaled.

Fig. 34 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method according to an embodiment.

The embodiment described with reference to fig. 34 illustrates a method of signaling information related to an intra prediction method for a case where a non-planar flag as described above with reference to fig. 33 is not used in an ISP.

At least some of the description made above with reference to fig. 22 may also be applied to the embodiment to be described with reference to fig. 34. Duplicate description will be omitted here.

For example, steps 3410, 3415, 3420, 3425, 3430, 3435, 3440, 3445, 3450, 3455, 3460, 3465, 3470, 3480, 3485, 3490, and 3495 may correspond to

steps

2210, 2215, 2220, 2225, 2230, 2235, 2240, 2245, 2250, 2255, 2260, 2265, 2270, 2280, 2285, 2290, and 2295, respectively.

Unlike step 2270, in step 3470, when the value of the MRL index is greater than 0 or when the value of the ISP flag is 1, an operation of signaling the non-planar flag may not be performed. That is, a condition of checking whether the value of the ISP flag is 1 may be added to the condition at step 3470.

In the embodiment described above with reference to fig. 33, a description has been made such that when the value of the ISP flag is 1, the planar mode is set to be unavailable, and thus the non-planar flag is not signaled. Thus, at step 3470, when the value of the ISP flag is 1, step 3490 may be subsequently performed, and the signaling of the non-planar flag at step 3480 and the checking of whether the value of the non-planar flag is 1 at step 3485 may not be performed.

Method for preferentially signaling non-planar indicia

Fig. 35 illustrates a method for preferentially signaling non-planar flags according to an embodiment.

At step 3510, a non-planar flag may be signaled.

At step 3520, it may be checked whether the value of the non-planar flag is 1.

After the non-plane flag is first signaled, when the value of the non-plane flag is 1, reconstruction (or setting) of an intra prediction mode may be performed in step 3530.

After the non-plane flag is first signaled, when the value of the non-plane flag is not 1, the intra prediction mode for the block may be set to the plane mode, and the reconstruction of the intra prediction mode may be skipped at step 3540.

Here, the process for reconstructing the intra prediction mode may include signaling information required for reconstruction of the intra prediction mode, such as an MPM flag.

Fig. 36 illustrates another method for preferentially signaling non-planar flags according to an embodiment.

At step 3610, a non-planar flag may be signaled.

At step 3620, it may be checked whether the value of the non-planar flag is 1.

After the non-planar flag is first signaled, when the value of the non-planar flag is 1, an operation of signaling information related to an additional intra prediction method may be performed at step 3630.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 1, the plane mode is not used as the intra prediction mode for the block, and thus an operation of signaling information related to an additional intra prediction method may be performed in order to reconstruct the intra prediction mode for the block.

After the non-planar flag is first signaled, when the value of the non-planar flag is not 1, an operation of signaling information related to an additional intra prediction method may be skipped at step 3640.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 1, the plane mode is used as an intra prediction mode for the block, and thus an operation of signaling information related to an additional intra prediction method required to reconstruct the intra prediction mode for the block may be skipped.

Here, the information related to the additional intra prediction method may include an MRL index and the like.

Fig. 37 illustrates a method for determining whether an operation of signaling information related to an MPM will be performed when a non-planar flag is preferentially signaled according to an embodiment.

In an embodiment, when the value of the non-plane flag is 1 (i.e., when the plane mode is not used as the intra prediction mode for the block), the intra prediction mode for the block may be determined by always using the MPM (instead of using an additional intra prediction method).

At step 3710, a non-planar flag may be signaled.

At step 3720, it may be checked whether the value of the non-planar flag is 1.

After the non-planar flag is first signaled, when the value of the non-planar flag is 1, the operation of signaling the MPM flag may be skipped and the MPM flag may be derived as 1 in step 3730.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 1, the plane mode is not used as the intra prediction mode for the block, and thus the intra prediction mode for the block may be determined using the MPM. Accordingly, since the MPM flag is derived as 1, an operation of signaling the MPM flag may be skipped and an operation of signaling the MPM index may be performed.

After the non-planar flag is first signaled, when the value of the non-planar flag is not 1, an operation of signaling the MPM flag may be performed in order to check whether the MPM will be used in step 3740.

Fig. 38 illustrates another method for determining whether an operation of signaling information related to an MPM will be performed when a non-planar flag is preferentially signaled according to an embodiment.

In an embodiment, whether planar mode will be used and whether MPM will be used may be determined independently. In other words, even if the value of the non-plane flag is 1 (i.e., even if the plane mode is not used as the intra prediction mode for the block), one intra prediction method among a plurality of intra prediction methods including MPM and the like may be selected, and an additional intra prediction method other than MPM may also be used.

At step 3810, a non-planar flag may be signaled.

At step 3820, it may be checked whether the value of the non-planar flag is 1.

After the non-planar flag is first signaled, when the value of the non-planar flag is 1, an operation of signaling information related to the MPM may be performed in step 3830.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 1, the plane mode is not used as the intra prediction mode for the block, and thus the intra prediction mode for the block can be reconstructed using the additional intra prediction mode. Accordingly, in order to determine whether the MPM will be used as an intra prediction mode for a block, information related to the MPM, such as an MPM flag, may be signaled.

After the non-planar flag is first signaled, when the value of the non-planar flag is not 1, an operation of signaling the MPM may be performed in step 3840 in order to check whether the MPM will be used.

That is, after the non-plane flag is first signaled, when the non-plane flag is 1, the plane mode is not used as the intra prediction mode for the block, and thus an operation of signaling information related to the MPM may be performed in order to reconstruct the intra prediction mode for the block.

Fig. 39 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when a non-plane flag is preferentially signaled, according to an embodiment.

The embodiment described with reference to fig. 39 illustrates a method of signaling information related to an intra prediction method for a case where a non-planar flag is preferentially signaled as described above with reference to fig. 37.

At least some of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 39. Duplicate description will be omitted here.

At step 3910, a MIP flag may be signaled.

At step 3915, it may be checked whether the value of the MIP flag is 1.

At step 3920, MIP mode may be signaled.

At step 3925, a non-planar flag may be signaled.

At step 3930, it may be checked whether the value of the non-planar flag is 1.

At step 3940, the MRL index may be signaled.

At step 3945, the MPM index may be signaled.

At step 3955, an MPM flag may be signaled.

In step 3960, it may be checked whether the value of the MPM flag is 1.

In step 3965, intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using Truncated Binary Coding (TBC).

At step 3970, it may be checked whether the value of the MRL index is greater than 0.

At step 3975, an ISP flag may be signaled.

At step 3985, it may be checked whether the value of the ISP flag is 1.

At step 3990, the ISP mode may be signaled.

In step 3995, setting for an intra prediction mode (or reconstruction of an intra prediction mode) may be performed. That is, based on the signaled information, the intra prediction mode for the target block may be determined.

According to the embodiment described above with reference to fig. 22, after the operation of signaling the MIP flag has been performed, the operation of signaling the MRL index may be performed.

Unlike this method, in the embodiment described with reference to fig. 39, after the operation of signaling the MIP flag has been performed, the operation of signaling the non-planar flag may be preferentially performed.

When the value of the non-planar flag is 1, an operation of signaling the MPM flag may be skipped, and an operation of signaling the MPM index and an operation of signaling the MRL index may be performed.

When the value of the MRL index is 0, an operation of signaling information related to the ISP may be subsequently performed.

When the value of the non-planar flag is 0, an operation of signaling the MPM flag may be performed.

When the value of the MPM flag is 0, information required to derive an intra prediction mode for a block among the remaining modes may be signaled.

When the value of the MPM flag is 1, the plane mode may be set to an intra prediction mode for the block, and an operation of signaling information related to the ISP may be conditionally performed.

When the value of the non-planar flag is 0, an operation of signaling information related to the MRL may be skipped.

Fig. 40 is a flowchart illustrating another method for signaling pieces of information related to an intra prediction method when a non-planar flag is preferentially signaled according to an embodiment.

The embodiment described with reference to fig. 40 shows a method of signaling information related to the intra prediction method for the case where the non-planar flag described above with reference to fig. 38 is preferentially signaled.

At least some of the descriptions made above with reference to fig. 22 and 39 may be applied to the embodiment to be described with reference to fig. 40. Duplicate description will be omitted here.

At step 4010, a MIP tag can be signaled.

In step 4015, it may be checked whether the value of the MIP flag is 1.

At step 4020, MIP mode can be signaled.

At step 4025, a non-planar token may be signaled.

In step 4030, it may be checked whether the value of the non-planar flag is 1.

At step 4040, the MRL index may be signaled.

At step 4042, it may be checked whether the value of the MRL index is greater than 0.

At step 4055, an MPM flag may be signaled.

In step 4060, it may be checked whether the value of the MPM flag is 1.

In step 4065, the intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

At step 4068, the MPM index may be signaled.

At step 4070, it may be checked whether the value of the MRL index is greater than 0.

At step 4075, an ISP flag may be signaled.

At step 4085, it may be checked whether the value of the ISP flag is 1.

At step 4090, the ISP mode may be signaled.

In step 4095, setting for an intra prediction mode (or reconstruction of an intra prediction mode) may be performed. That is, based on the signaled information, the intra prediction mode for the target block may be determined.

According to the embodiment described above with reference to fig. 22, after the operation of signaling the MIP flag is performed, the operation of signaling the MRL index may be performed. In the embodiment described with reference to fig. 40, the operation of signaling the non-planar tag may be preferentially performed after the operation of signaling the MIP tag has been performed.

When the value of the non-plane flag is 0, the plane mode may be set to the intra prediction mode for the block, and an operation of signaling information related to MRL, an operation of signaling information related to MPM, and an operation of reconstructing the intra prediction mode may be skipped.

For signaling when a non-planar flag is preferentially signaled depending on whether a planar mode is to be used Method for transmitting information related to specific intra prediction method

Fig. 41 illustrates a method for signaling information related to a specific intra prediction method according to whether a planar mode will be used when a non-planar flag is preferentially signaled according to an embodiment.

For example, the specific intra prediction method may be an intra prediction method related to the sub-partition.

At step 4110, a non-planar flag may be signaled.

In step 4120, it may be checked whether the value of the non-planar flag is 1.

After the non-plane flag is first signaled, when the value of the non-plane flag is 1, an operation of signaling information related to a specific intra prediction method using only the plane mode may be skipped at step 4130. Here, information related to a specific intra prediction method may be derived as 0.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 1, the plane mode is not used as the intra prediction mode for the block, and thus a specific intra prediction mode using only the plane mode may not be used as well. Accordingly, an operation of signaling a specific intra prediction method may be skipped, and a flag of the specific intra prediction method may be derived as 0 in order to indicate that the specific intra prediction method will not be used.

After the non-plane flag is first signaled, when the value of the non-plane flag is 0, an operation of signaling information related to a specific intra prediction method using only the plane mode may be skipped at step 4140. Here, information related to a specific intra prediction method may be derived as 1.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 0, the plane mode is used as an intra prediction mode for the block, and thus a specific intra prediction mode using only the plane mode may also be used. Accordingly, an operation of signaling a specific intra prediction method may be skipped, and a flag of the specific intra prediction method may be derived as 1 in order to indicate that the specific intra prediction method will be used.

Fig. 42 illustrates a method for signaling MRL-related information according to whether a planar mode will be used when a non-planar flag is preferentially signaled according to an embodiment.

In the embodiment described with reference to fig. 42, a method for signaling information related to MRL when a non-plane flag is preferentially signaled and a plane mode is not available in MRL may be described. Further, in embodiments, operations to signal information related to the MRL may be skipped.

At step 4210, a non-planar flag may be signaled.

In step 4220, it may be checked whether the value of the non-planar flag is 1.

After the non-planar flag is first signaled, when the value of the non-planar flag is 1, information related to the MRL may be signaled in step 4230.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 1, the plane mode is not used as an intra prediction mode for a block, and thus an MRL in which the plane mode is not available may also be available.

After the non-planar flag is first signaled, when the value of the non-planar flag is 0, an operation of signaling the MRL-related information may be skipped at step 4240.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 0, the plane mode is used as an intra prediction mode for a block, and thus an MRL in which the plane mode is not available may also be unavailable. Accordingly, after the non-planar flag is first signaled, when the value of the non-planar flag is 0, the operation of signaling the MRL flag may be skipped, and the MRL flag may be derived as 0.

In an embodiment, when the value of the MRL index is greater than 0, the planar mode may not be used. Accordingly, after the non-plane flag is first signaled, when the value of the non-plane flag is 0, the MRL flag may be signaled, the operation of signaling the MRL index may be skipped, and the MRL index may be derived as 0.

Fig. 43 illustrates a method for signaling information related to an ISP according to whether a planar mode will be used when a non-planar flag is preferentially signaled according to an embodiment.

As described above with reference to fig. 26, planar mode may not be available in an ISP.

In the embodiment described with reference to fig. 43, a method for signaling information related to an ISP when a non-planar flag is preferentially signaled and a planar mode is not available in the ISP may be described, and an operation of signaling information related to the ISP may be skipped.

At step 4310, a non-planar flag may be signaled.

At step 4320, it may be checked whether the value of the non-planar flag is 1.

After the non-flat flag is first signaled, when the value of the non-flat flag is 1, information related to the ISP may be signaled in step 4330.

After the non-flat flag is first signaled, when the value of the non-flat flag is 0, an operation of signaling information related to the ISP may be skipped at step 4240.

That is, after the non-plane flag is first signaled, when the value of the non-plane flag is 0, a plane mode is used as an intra prediction mode for a block, and thus an ISP in which the plane mode is not available may also be unavailable. Therefore, after the non-planar flag is first signaled, when the value of the non-planar flag is 0, the operation of signaling the ISP flag may be skipped, and the ISP flag may be derived as 0.

Fig. 44 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when a non-plane flag is preferentially signaled and a plane mode is not available in an MRL according to an embodiment.

The embodiment described with reference to fig. 44 illustrates a method of signaling information related to an intra prediction method for a case where a non-plane flag as described above with reference to fig. 42 is preferentially signaled and a plane mode is not available in MRL.

At least some of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 44. Duplicate description will be omitted here.

At step 4410, a MIP tag may be signaled.

At step 4415, it may be checked whether the value of the MIP flag is 1.

At step 4420, MIP mode can be signaled.

At step 4425, a non-planar flag may be signaled.

At step 4430, it may be checked whether the value of the non-planar flag is 1.

At step 4455, an MPM flag may be signaled.

At step 4460, it may be checked whether the value of the MPM flag is 1.

In step 4465, an intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using the TBC.

At step 4466, an MPM index may be signaled.

At step 4468, the MRL index may be signaled.

At step 4470, it may be checked whether the value of the MRL index is greater than 0.

At step 4475, an ISP flag may be signaled.

At step 4485, it may be checked whether the value of the ISP flag is 1.

At step 4490, the ISP mode may be signaled.

At step 4495, setting for the intra prediction mode (or reconstruction of the intra prediction mode) may be performed. That is, based on the signaled information, the intra prediction mode for the target block may be determined.

According to the embodiment described above with reference to fig. 22, after the operation of signaling the MIP flag has been performed, the operation of signaling the MRL index may be performed. Unlike this method, in the embodiment described with reference to fig. 44, after the operation of signaling the MIP flag has been performed, the operation of signaling the non-planar flag may be preferentially performed.

When the value of the MPM flag is 1, the plane mode may be set to an intra prediction mode for the block.

In an embodiment, when the value of the non-planar flag is 0, an operation of signaling information related to the ISP and an operation of signaling information related to the MRL may be skipped.

Fig. 45 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when a non-plane flag is preferentially signaled and a plane mode is not available in an MRL according to an embodiment.

The embodiment described with reference to fig. 45 shows a method for signaling information related to an intra prediction method for a case where a non-planar flag as described above with reference to fig. 43 is preferentially signaled and a planar mode is not available in an ISP.

At least some of the description made above with reference to fig. 22 may be applied to the embodiment described below with reference to fig. 45. Duplicate description will be omitted here.

The embodiment to be described with reference to fig. 45 may be such a method: skipping the operation of signaling information related to the ISP when the value of the non-flat flag is not 1 is added to the method described in the embodiment described above with reference to fig. 39 and 40. From this point of view, at least some of the descriptions made above with reference to fig. 39 and 40 may also be applied to the embodiment to be described with reference to fig. 45. Duplicate description will be omitted here.

At step 4510, a MIP flag may be signaled.

At step 4515, it may be checked whether the value of the MIP flag is 1.

At step 4520, MIP mode may be signaled.

At step 4525, a non-planar flag may be signaled.

At step 4530, it may be checked whether the value of the non-planar flag is 1.

At step 4568, the MRL index may be signaled.

At step 4570, it may be checked whether the value of the MRL index is greater than 0.

In step 4572, the value of the MPM flag may be set to 1.

At step 4575, an ISP flag may be signaled.

At step 4585, it may be checked whether the value of the ISP flag is 1.

At step 4590, the ISP mode may be signaled.

In step 4591, an MPM flag may be signaled.

In step 4592, it may be checked whether the value of the MPM flag is 1.

In step 4593, the MPM index may be signaled.

In step 4594, the intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using the TBC.

In step 4595, the setting for the intra prediction mode (or the reconstruction of the intra prediction mode) may be performed. That is, based on the signaled information, the intra prediction mode for the target block may be determined.

Unlike this approach, in embodiments, the operation of signaling the non-planar tag may be performed preferentially after the operation of signaling the MIP tag has been performed.

Fig. 46 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when an MPM flag is preferentially signaled according to an embodiment.

The embodiment described with reference to fig. 46 illustrates a method of signaling information related to an intra prediction method for the case where the MPM flag is signaled with the highest priority.

At least some of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 46. Duplicate description will be omitted here.

In contrast to the embodiment described above with reference to fig. 45, the embodiment described above with reference to fig. 46 may be a method for preferentially performing an operation of signaling an MPM flag. From this point of view, at least some of the description made above with reference to fig. 45 may be applied to the embodiment to be described with reference to fig. 46. Duplicate description will be omitted here.

At step 4610, a MIP tag may be signaled.

At step 4615, it may be checked whether the value of the MIP flag is 1.

At step 4620, MIP mode may be signaled.

At step 4622, an MPM flag may be signaled.

At step 4624, it may be checked whether the value of the MPM flag is 1.

At step 4625, a non-planar flag may be signaled.

At step 4630, it may be checked whether the value of the non-flat flag is 1.

At step 4645, the MPM index may be signaled.

At step 4647, the MRL index may be signaled.

At step 4649, it may be checked whether the value of the MRL index is greater than 0.

In step 4665, the intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

In step 4667, it may be checked whether the intra prediction mode for the block is planar mode.

At step 4675, the ISP flag may be signaled.

At step 4685, it may be checked whether the value of the ISP flag is 1.

At step 4690, the ISP mode may be signaled.

In step 4695, the setting for the intra prediction mode (or the reconstruction of the intra prediction mode) may be performed. That is, based on the signaled information, the intra prediction mode for the target block may be determined.

According to the embodiment described above with reference to fig. 22, after the operation of signaling the MIP flag has been performed, the operation of signaling the MRL index may be performed. Unlike this method, in the embodiment described with reference to fig. 46, after the operation of signaling the MIP flag has been performed, the operation of signaling the MPM flag may be preferentially performed, and the operation of signaling the non-planar flag may be subsequently performed.

The embodiment described with reference to fig. 46 may be a method of: an operation of skipping the signaling of information related to the ISP when the value of the non-plane flag is not 1 is added to the method described in the embodiment described above with reference to fig. 39 and 40.

For the same reason as the case where the plane mode is always included in the MPM list, if the plane mode is not usable as the intra prediction mode for the block when the value of the MPM flag is 0, step 4667 may be skipped.

For using priority signaling information to determine whether to signal execution of MIP-related informationOperation ofMethod (2)

Fig. 47, 48 and 49 illustrate methods for using information signaled before a MIP flag is signaled to determine whether an operation of signaling MIP-related information will be performed.

Fig. 47 illustrates a method for determining whether an operation of signaling MIP-related information will be performed based on a non-planar flag when the non-planar flag is preferentially signaled according to an embodiment.

In the embodiment described with reference to fig. 47, the non-planar flag may be preferentially signaled, and it may be determined whether an operation of signaling MIP-related information will be performed based on the non-planar flag.

At step 4710, a non-planar flag may be signaled.

At step 4720, it may be checked whether the value of the non-planar flag is 1.

After the non-planar flag is first signaled, the operation of signaling MIP-related information may be skipped at step 4730 when the value of the non-planar flag is 1.

In an embodiment, the intra prediction mode for a block may be reconstructed using the reference to the MPM list and the property of MIP that uses mutual exclusion.

Generally, MIPs may have a dedicated intra prediction mode for MIPs. When the value of the MIP flag is 1, a separate MPM list for MIP may be configured and an operation of signaling the non-planar flag may not be performed. Hereinafter, an MPM using a separate MPM list for an MIP may be referred to as a "MIP MPM".

Therefore, the case where the value of the non-planar flag signaled first is 1 may indicate that MIP is not used and that the MPM flag and MPM index are referenced. Accordingly, after the non-planar flag is first signaled, when the value of the non-planar flag is 1, an operation of signaling information related to MIP may be skipped.

After the non-planar flag is first signaled, when the value of the non-planar flag is 0, an operation of signaling MIP-related information may be performed at step 4740.

A case where the value of the first signaled non-flat flag is 0 may indicate that the non-flat flag is not signaled. Accordingly, in this case, the value of the MPM flag may be 0, and thus an operation of signaling the information related to the MIP may be performed.

Fig. 48 illustrates another method for determining whether an operation of signaling MIP-related information will be performed based on a non-planar flag when the non-planar flag is preferentially signaled according to an embodiment.

In the embodiment described with reference to fig. 48, the non-planar flag may be preferentially signaled, and it may be determined whether an operation of signaling MIP-related information will be performed based on the non-planar flag.

At step 4810, a non-planar token may be signaled.

At step 4820, it may be checked whether the value of the non-planar flag is 1.

After the non-planar flag is first signaled, when the value of the non-planar flag is 1, an operation of signaling MIP-related information may be performed in step 4830.

After the non-planar flag is first signaled, the operation of signaling MIP related information may be skipped at step 4840 when the value of the non-planar flag is 0.

In an embodiment, when reconstructing an intra prediction mode for a block, a characteristic that reference to an MPM list and use of MIP are mutually exclusive may be used. From this perspective, the embodiment described with reference to fig. 48 may be similar to the embodiment described above with reference to fig. 47.

In the embodiment described above with reference to fig. 47, when the value of the non-plane flag is 1, the operation of signaling the information related to MIP may be skipped, and when the value of the non-plane flag is 0, the operation of signaling the information related to MIP may be performed. In addition, in the embodiment described above with reference to fig. 48, when the value of the non-plane flag is 1, the operation of signaling the information related to MIP may be performed, and when the value of the non-plane flag is 0, the operation of signaling the information related to MIP may be skipped.

Generally, MIPs may have a dedicated intra prediction mode for MIPs. When the value of the MIP flag is 1, a separate MPM list for MIP may be configured and an operation of signaling the non-planar flag may not be performed.

In the embodiment described above with reference to fig. 47, the planar mode may exist in the MPM list. Because the planar mode may exist in the MPM list, there may be a dependency between the MPM flag and the non-planar flag.

Conversely, in the embodiment described with reference to fig. 48, the non-planar flag and the MPM flag may be signaled separately. Accordingly, since the non-plane flag and the MPM flag are separately signaled, when the value of the non-plane flag is 0 in an embodiment, the plane mode may be determined as the intra prediction mode for the block. Further, the planar mode may not correspond to the intra prediction mode used in MIP. Accordingly, when the value of the non-planar flag is 0, an operation of signaling information related to MIP may be skipped. Further, the operation of signaling the information related to the MIP may be performed only when the value of the non-plane flag is 1.

Fig. 49 illustrates a method for determining whether an operation of signaling MIP-related information will be performed based on an MPM flag when the MPM flag is preferentially signaled, according to an embodiment.

In the embodiment described with reference to fig. 49, the MPM flag may be preferentially signaled, and it may be determined whether an operation of signaling the information related to the MIP will be performed based on the MPM flag.

At step 4910, an MPM flag may be signaled.

At step 4920, it may be checked whether the value of the MPM flag is 1.

After the MPM flag is first signaled, when the value of the MPM flag is 1, the signaling of the MIP-related information may be skipped at step 4930.

In an embodiment, when reconstructing intra prediction modes for a block, a characteristic that reference to an MPM list and use of MIP are mutually exclusive may be used. From this perspective, the embodiment described with reference to fig. 49 may be similar to the embodiment described above with reference to fig. 47. However, in the embodiment described above with reference to fig. 47, whether or not the MIP-related information is to be signaled may be determined based on the non-planar flag, but in the embodiment described with reference to fig. 49, whether or not the MIP-related information is to be signaled may be determined based on the MPM flag.

Accordingly, the case where the value of the MPM flag is 1 may represent that the MPM list is used to reconstruct the intra prediction mode for the block. Accordingly, when the value of the MPM flag is 1, the MIP mode is not used, and thus, when the value of the MPM flag is 1, an operation of signaling information related to MIP may be skipped.

After the MPM flag is first signaled, when the value of the MPM flag is 0, an operation of signaling the information related to the MIP may be performed in step 4930.

As described above with respect to

steps

4920 and 4930, the operation of signaling MIP-related information may be performed only when the value of the MPM flag is 0.

Fig. 50 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP will be performed based on a priority signaled non-planar flag according to an embodiment.

An embodiment to be described with reference to fig. 50 illustrates a method for signaling information related to an intra prediction method for a case where a non-planar flag is preferentially signaled as described above with reference to fig. 47 and it is determined whether an operation of signaling information related to MIP will be performed based on the non-planar flag.

At least a portion of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 50. Duplicate description will be omitted here.

At step 5005, a non-planar flag may be signaled.

In step 5006, it may be checked whether the value of the non-planar flag is 1.

At step 5010, a MIP flag may be signaled.

In step 5015, it may be checked whether the value of the MIP flag is 1.

At step 5020, MIP mode may be signaled.

At step 5022, the ISP flag may be signaled.

At step 5023, it may be checked whether the value of the ISP flag is 1.

At step 5024, the ISP mode may be signaled.

At step 5055, an MPM flag may be signaled.

At step 5060, it may be checked whether the value of the MPM flag is 1.

At step 5065, an intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

At step 5068, an MPM index may be signaled.

At step 5069, the MRL index may be signaled.

At step 5070, it may be checked whether the value of the MRL index is greater than 0.

At step 5075, an ISP flag may be signaled.

At step 5085, it may be checked whether the value of the ISP flag is 1.

At step 5090, the ISP mode may be signaled.

At step 5095, a setting for an intra prediction mode (or a reconstruction of the intra prediction mode) may be performed. That is, the intra prediction mode for the target block may be determined based on the signaled information.

In the embodiment described with reference to fig. 50, the non-planar flag may be signaled with the highest priority. When the value of the non-flat flag is 1, an operation of signaling information related to MIP may be skipped. When the value of the non-planar flag is 0, an operation of signaling information related to MIP may be performed.

Fig. 51 is a flowchart illustrating another method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on a priority signaled non-plane flag according to an embodiment.

An embodiment to be described with reference to fig. 51 shows a method for signaling information related to an intra prediction method for a case where a non-planar flag is preferentially signaled as described above with reference to fig. 48 and it is determined whether an operation of signaling information related to MIP will be performed based on the non-planar flag.

At least a part of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 51. Duplicate description will be omitted here.

At step 5105, a non-planar token may be signaled.

In step 5106, it may be checked whether the value of the non-planar flag is 1.

At step 5107, an ISP flag may be signaled.

In step 5108, it may be checked whether the value of the ISP flag is 1.

At step 5109, ISP mode may be signaled.

At step 5110, a MIP tag can be signaled.

In step 5115, it may be checked whether the value of the MIP flag is 1.

At step 5120, MIP mode can be signaled.

In step 5145, the MRL index may be signaled.

At step 5170, it may be checked whether the value of the MRL index is greater than 0.

At step 5175, the ISP flag may be signaled.

At step 5185, it may be checked whether the value of the ISP flag is 1.

At step 5190, the ISP mode may be signaled.

At step 5191, an MPM flag may be signaled.

In step 5192, it may be checked whether the value of the MPM flag is 1.

At step 5193, the MPM index may be signaled.

In step 5194, intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

In step 5195, setting for an intra prediction mode (or reconstruction of an intra prediction mode) may be performed. That is, the intra prediction mode for the target block may be determined based on the signaled information.

In the embodiment described with reference to fig. 51, the non-planar flag may be signaled with the highest priority. When the value of the non-planar flag is 1, an operation of signaling information related to MIP may be performed. When the value of the non-planar flag is 0, the operation of signaling the information related to MIP may be skipped.

Fig. 52 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP will be performed based on the MPM flag that is signaled preferentially according to an embodiment.

An embodiment to be described with reference to fig. 52 shows a method for signaling information related to an intra prediction method for a case where an MPM flag is preferentially signaled as described above with reference to fig. 49 and it is determined whether an operation of signaling information related to MIP will be performed based on the MPM flag.

At least a portion of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 52. Duplicate description will be omitted here.

At step 5201, an MPM flag may be signaled.

In step 5202, it may be checked whether the value of the MPM flag is 1.

At step 5205, a non-planar token may be signaled.

At step 5206, it may be checked whether the value of the non-planar flag is 1.

At step 5210, a MIP flag may be signaled.

In step 5215, it may be checked whether the value of the MIP flag is 1.

At step 5220, MIP mode may be signaled.

At step 5245, the MPM index may be signaled.

In step 5247, the MRL index may be signaled.

In step 5265, the intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

At step 5270, it may be checked whether the value of the MRL index is greater than 0.

At step 5275, an ISP flag may be signaled.

At step 5285, it may be checked whether the value of the ISP flag is 1.

At step 5290, the ISP mode may be signaled.

In step 5295, setting for an intra prediction mode (or reconstruction of an intra prediction mode) may be performed. That is, the intra prediction mode for the target block may be determined based on the signaled information.

In the embodiment described above with reference to fig. 52, the MPM flag may be signaled with the highest priority. When the value of the MPM flag is 1, an operation of signaling information related to MIP may be skipped. When the value of the MPM flag is 0, an operation of signaling information related to the MIP may be performed.

Fig. 53 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on a non-plane flag signaled preferentially and a plane mode is not available in an ISP according to an embodiment.

At least a part of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 53. Duplicate description will be omitted here.

The embodiment described above with reference to fig. 53 may be a combination of the embodiment described above with reference to fig. 47 and 50 and the embodiment described above with reference to fig. 43 and 45. According to the embodiment described with reference to fig. 47, the non-planar flag may be preferentially signaled, and it may be determined whether an operation of signaling the MIP-related information will be performed based on the non-planar flag. According to the embodiment described above with reference to fig. 43, the planar mode may not be available in the ISP, and when the value of the non-planar flag is 0, an operation of signaling information related to the ISP may be skipped.

From this point of view, at least a part of the description made above with reference to fig. 47, 50, 43, and 45 may also be applied to the embodiment to be described with reference to fig. 53. A repetitive description thereof may be omitted.

At step 5305, a non-planar flag may be signaled.

At step 5306, it may be checked whether the value of the non-flat flag is 1.

At step 5310, a MIP flag may be signaled.

At step 5315, it may be checked whether the value of the MIP flag is 1.

At step 5320, MIP mode can be signaled.

In step 5321, an MPM flag may be signaled.

In step 5322, it may be checked whether the value of the MPM flag is 1.

In step 5323, an intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using the TBC.

At step 5345, the MPM index may be signaled.

At step 5347, the MRL index may be signaled.

At step 5370, it may be checked whether the value of the MRL index is greater than 0.

At step 5375, an ISP flag may be signaled.

At step 5385, it may be checked whether the value of the ISP flag is 1.

At step 5390, the ISP mode may be signaled.

In step 5395, setting for an intra prediction mode (or reconstruction of the intra prediction mode) may be performed. That is, the intra prediction mode for the target block may be determined based on the signaled information.

As in the case of the embodiment described above with reference to fig. 45, in the embodiment described with reference to fig. 53, when the value of the non-planar flag is 0, the operation of signaling information related to the ISP may be skipped.

As in the case of the embodiment described above with reference to fig. 50, in the embodiment described with reference to fig. 53, an operation of signaling the information related to MIP may be performed only when the value of the non-planar flag is 0.

Fig. 54 is a flowchart illustrating another method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on a non-plane flag signaled preferentially and a plane mode is not available in an ISP according to an embodiment.

At least a portion of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 54. Duplicate description will be omitted here.

The embodiment described above with reference to fig. 54 may be a combination of the embodiment described above with reference to fig. 47 and 51 and the embodiment described above with reference to fig. 43 and 45. According to the embodiment described with reference to fig. 47, the non-planar flag may be preferentially signaled, and it may be determined whether an operation of signaling the MIP-related information will be performed based on the non-planar flag. According to the embodiment described above with reference to fig. 43, the planar mode may not be available in the ISP, and when the value of the non-planar flag is 0, an operation of signaling information related to the ISP may be skipped.

From this point of view, at least a part of the description made above with reference to fig. 47, 51, 43, and 45 may also be applied to the embodiment to be described with reference to fig. 54. A repetitive description thereof may be omitted.

At step 5405, a non-planar flag may be signaled.

In step 5406, it may be checked whether the value of the non-planar flag is 1.

At step 5410, a MIP tag can be signaled.

At step 5415, it may be checked whether the value of the MIP flag is 1.

At step 5420, MIP mode can be signaled.

At step 5447, the MRL index may be signaled.

In step 5470, it may be checked whether the value of the MRL index is greater than 0.

In step 5475, an ISP flag may be signaled.

At step 5485, it may be checked whether the value of the ISP flag is 1.

At step 5490, the ISP mode may be signaled.

At step 5491, an MPM flag may be signaled.

In step 5492, it may be checked whether the value of the MPM flag is 1.

At step 5493, the MPM index may be signaled.

In step 5494, intra prediction modes may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

In step 5495, setting for an intra prediction mode (or reconstruction of an intra prediction mode) may be performed. That is, the intra prediction mode for the target block may be determined based on the signaled information.

As in the case of the embodiment described above with reference to fig. 45, in the embodiment described with reference to fig. 54, when the value of the non-planar flag is 0, the operation of signaling information related to the ISP may be skipped.

As in the case of the embodiment described above with reference to fig. 51, in the embodiment described with reference to fig. 54, an operation of signaling the information related to MIP may be performed only when the value of the non-planar flag is 0.

Fig. 55 is a flowchart illustrating another method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on a non-plane flag signaled preferentially and a plane mode is not available in an ISP according to an embodiment.

At least a part of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 55. Duplicate description will be omitted here.

The embodiment described above with reference to fig. 55 may be a combination of the embodiment described above with reference to fig. 48 and 51 and the embodiment described above with reference to fig. 43 and 45. According to the embodiment described with reference to fig. 48, the non-planar flag may be preferentially signaled, and it may be determined whether an operation of signaling the MIP-related information will be performed based on the non-planar flag. According to the embodiment described above with reference to fig. 43, the planar mode may not be available in the ISP, and when the value of the non-planar flag is 0, an operation of signaling information related to the ISP may be skipped.

From this point of view, at least a part of the description made above with reference to fig. 48, 51, 43, and 45 may also be applied to the embodiment to be described with reference to fig. 55. A repetitive description thereof may be omitted.

At step 5505, a non-planar token may be signaled.

At step 5506, it may be checked whether the value of the non-planar flag is 1.

At step 5510, a MIP tag may be signaled.

In step 5515, it may be checked whether the value of the MIP flag is 1.

At step 5520, MIP mode can be signaled.

In step 5547, the MRL index may be signaled.

At step 5570, it may be checked whether the value of the MRL index is greater than 0.

At step 5575, the ISP flag may be signaled.

In step 5585, it may be checked whether the value of the ISP flag is 1.

At step 5590, the ISP mode may be signaled.

In step 5591, an MPM flag may be signaled.

In step 5592, it may be checked whether the value of the MPM flag is 1.

In step 5593, the MPM index may be signaled.

In step 5594, an intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

In step 5595, setting for an intra prediction mode (or reconstruction of an intra prediction mode) may be performed. That is, the intra-prediction mode for the target block may be determined based on the signaled information.

As in the case of the embodiment described above with reference to fig. 45, in the embodiment described with reference to fig. 55, when the value of the non-planar flag is 0, an operation of signaling information related to the ISP may be skipped.

As in the case of the embodiment described above with reference to fig. 51, in the embodiment described with reference to fig. 55, an operation of signaling MIP-related information may be performed only when the value of the non-plane flag is 1.

Fig. 56 is a flowchart illustrating a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling MIP-related information will be performed based on an MPM flag that is signaled preferentially and when a plane mode is not available in an ISP according to an embodiment.

At least a portion of the description made above with reference to fig. 22 may be applied to the embodiment to be described with reference to fig. 56. Duplicate description will be omitted here.

The embodiment described above with reference to fig. 56 may be a combination of the embodiment described above with reference to fig. 49 and 52 and the embodiment described above with reference to fig. 43 and 45. According to the embodiment described with reference to fig. 49, the MPM flag may be preferentially signaled, and it may be determined whether an operation of signaling the information related to the MIP will be performed based on the MPM flag. According to the embodiment described above with reference to fig. 43, the planar mode may not be available in the ISP, and when the value of the non-planar flag is 0, an operation of signaling information related to the ISP may be skipped.

From this point of view, at least a part of the description made above with reference to fig. 49, 52, 43, and 45 may also be applied to the embodiment to be described with reference to fig. 56. A repetitive description thereof may be omitted.

At step 5601, an MPM flag may be signaled.

At step 5602, it may be checked whether the value of the MPM flag is 1.

At step 5605, a non-planar token may be signaled.

At step 5606, it may be checked whether the value of the non-flat flag is 1.

At step 5610, a MIP flag may be signaled.

In step 5615, it may be checked whether the value of the MIP flag is 1.

At step 5620, MIP mode may be signaled.

In step 5665, an intra prediction mode may be signaled. The signaled intra prediction mode may be used to perform intra prediction for the block. The intra prediction mode may be signaled using a TBC.

At step 5668, an MPM index may be signaled.

At step 5669, the MRL index may be signaled.

At step 5670, it may be checked whether the value of the MRL index is greater than 0.

At step 5675, an ISP flag may be signaled.

At step 5685, it may be checked whether the value of the ISP flag is 1.

At step 5690, the ISP mode may be signaled.

In step 5695, setting for the intra prediction mode (or reconstruction of the intra prediction mode) may be performed. That is, the intra prediction mode for the target block may be determined based on the signaled information.

As in the case of the embodiment described above with reference to fig. 45, in the embodiment described with reference to fig. 56, when the value of the non-planar flag is 0, the operation of signaling information related to the ISP may be skipped.

Further, as in the case of the embodiment described above with reference to fig. 52, in the embodiment described with reference to fig. 56, an operation of signaling the information related to the MIP may be performed only when the value of the MPM flag is 0.

Syntax structure of signaling method

In the drawing indicating the syntax structure, syntax elements written in italics may indicate added or changed portions, compared to the syntax structure illustrated in fig. 23. In contrast to the syntax structure shown in fig. 23, a syntax element that overlaps with the horizontal line at the center of the syntax element may represent a deleted or removed portion. Thus, a syntax element that overlaps the horizontal line at the center of the syntax element may be considered to be illustrated for comparison only, rather than actually present.

Further, in the following drawings indicating a syntax structure, a drawing showing a front stage of a specific syntax structure and a drawing showing a rear stage of the specific syntax structure may be considered to be connected to each other. The syntax in the drawing indicating the previous section may be executed, and then the syntax in the drawing indicating the subsequent section may be subsequently executed.

Fig. 57 shows a first syntax structure according to the embodiment.

The first syntax structure may be a syntax structure corresponding to a method for signaling pieces of information related to an intra prediction method as described above with reference to fig. 34.

According to the first syntax structure, a condition that the ISP flag is 0 (i.e., "intra _ sub _ flags _ mode _ flag [ x0] [ y0] ═ 0") may be added as a signaling condition for the non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0 ]).

Fig. 58 illustrates a second syntax structure according to the embodiment.

The second syntax structure may be a syntax structure corresponding to a method for signaling pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled as described above with reference to fig. 39.

According to the second syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]).

The second syntax structure may correspond to a case where the plane mode exists in the MPM list.

When the value of the non-planar flag is 1, the MPM flag may be skipped and the MPM flag may be derived as 1.

When the value of the non-planar flag is 1, an operation of signaling the MPM flag may be skipped, and the MPM flag may be derived as 1. In addition, when the value of the non-plane flag is 1, an operation of signaling the MPM index and the MRL index may be performed.

When the value of the non-planar flag is 0, the MPM flag may be signaled. When the value of the MPM flag is 1, the intra prediction mode for the block may be derived as a planar mode, and an operation of signaling the intra prediction mode for the block may be skipped.

When the value of the MPM flag is 0 and the value of the non-plane flag is 0, a determination may be made that MPM is not used, and the intra prediction mode for the block may be reconstructed by signaling the remaining modes.

Fig. 59 shows a third syntax structure according to an embodiment.

The third syntax structure may be a syntax structure corresponding to another method for signaling pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled as described above with reference to fig. 40.

According to the third syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]).

Fig. 60 illustrates a front stage of a fourth syntax structure according to an embodiment.

Fig. 61 shows a later section of a fourth syntax structure according to an embodiment.

The fourth syntax structure may be a syntax structure corresponding to the method for signaling pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled and the plane mode is not available in the MRL as described above with reference to fig. 44.

According to the fourth syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]). In addition, an operation of signaling information related to the ISP (i.e., intra _ sub _ aspects _ mode _ flag [ x0] [ y0] and intra _ sub _ spaces _ flag [ x0] [ y0]) may be performed only when the value of the non-plane flag is 1.

The fourth syntax structure may correspond to a case where the plane mode exists in the MPM list.

When the value of the non-planar flag is 1, an operation of signaling the MPM flag may be skipped, and the MPM flag may be derived as 1.

When the value of the non-planar flag is 1, an operation of signaling the MPM index, the MRL index, and the information related to the ISP may be performed. When the value of the non-planar flag is 0, the MPM flag may be signaled. When the value of the MPM flag is 1, the intra prediction mode for the block may be derived as a planar mode, and an operation of signaling the intra prediction mode for the block may be skipped.

Fig. 62 illustrates a front segment of a fifth syntax structure according to an embodiment.

Fig. 63 shows a later section of a fifth syntax structure according to an embodiment.

The fifth syntax structure may be a syntax structure corresponding to the method for signaling pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled and the plane mode is not available in the MRL as described above with reference to fig. 45.

According to the fifth syntax structure, the operation of signaling the non-plane flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]). In addition, an operation of signaling information related to the ISP (i.e., intra _ sub _ aspects _ mode _ flag [ x0] [ y0] and intra _ sub _ spaces _ flag [ x0] [ y0]) may be performed only when the value of the non-plane flag is 1.

Fig. 64 shows a front stage of a sixth syntax structure according to an embodiment.

Fig. 65 shows a later section of a sixth syntax structure according to an embodiment.

The sixth syntax structure may be a syntax structure corresponding to a method for signaling pieces of information related to the intra prediction method when the MPM flag is preferentially signaled as described above with reference to fig. 46.

According to the sixth syntax structure, the MPM flag (i.e., intra _ luma _ MPM _ flag [ x0] [ y0]) may be preferentially signaled, and the non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be subsequently signaled.

Furthermore, according to the sixth syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]). In addition, an operation of signaling information related to the ISP (i.e., intra _ sub _ aspects _ mode _ flag [ x0] [ y0] and intra _ sub _ spaces _ flag [ x0] [ y0]) may be performed only when the value of the non-plane flag is 1.

Since the case where the value of the MPM flag is 0 actually matches the case where the value of the non-flat flag is 1, an operation of signaling information related to the ISP can be performed even in the case where the value of the MPM flag is 0.

Fig. 66 illustrates a front segment of a seventh syntax structure according to an embodiment.

Fig. 67 shows a later section of a seventh syntax structure according to an embodiment.

The seventh syntax structure may be a syntax structure corresponding to the method for signaling the pieces of information related to the intra prediction method when it is determined whether the information related to the MIP is to be signaled based on the non-plane flag signaled with priority as described above with reference to fig. 50.

According to the seventh syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]). Further, the operation of signaling MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]) may be performed only when the value of the non-plane flag is 0.

The seventh syntax structure may correspond to a case where the plane mode exists in the MPM list. According to the seventh syntax structure, when the value of the non-plane flag is 1, the operation of signaling the MPM flag may be skipped, and the MPM flag may be derived as 1.

When the value of the non-planar flag is 1, an operation of signaling the MPM index, the MRL index, and information related to the ISP may be performed. When the value of the non-planar flag is 0, the MPM flag may be signaled. When the value of the MPM flag is 1, the intra prediction mode for the block may be derived as a planar mode, and an operation of signaling the intra prediction mode for the block may be skipped.

When the value of the MPM flag is 0 and the value of the non-plane flag is 0, a determination that the MPM is not used may be made and the intra prediction mode for the block may be reconstructed by signaling the remaining modes.

Fig. 68 shows a front stage of an eighth syntax structure according to an embodiment.

Fig. 69 shows a back section of an eighth syntax structure according to an embodiment.

According to the eighth syntax structure, the operation of signaling the non-plane flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y 0). Further, the operation of signaling MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]) may be performed only when the value of the non-plane flag is 0.

Fig. 70 shows a front stage of a ninth syntax structure according to an embodiment.

Fig. 71 shows a later stage of a ninth syntax structure according to an embodiment.

The ninth syntax structure may be a syntax structure corresponding to another method for signaling pieces of information related to the intra prediction method when it is determined whether the information related to the MIP is to be signaled based on the non-plane flag signaled with priority as described above with reference to fig. 51.

According to the ninth syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be performed at a higher priority than signaling the MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]), signaling the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0]), and signaling the ISP-related information (i.e., intra _ sub _ partitionings _ mode _ flag [ x0] [ y0] and intra _ sub _ partitionings _ flag [ x0] [ y0 ]).

According to the ninth syntax structure, only when the value of the non-plane flag is 1, the operation of signaling the information related to MIP, the operation of signaling the information related to MRL, and the operation of signaling the information related to MPM can be performed.

The ninth syntax structure may correspond to a case where the plane mode is not present in the MPM list. According to the ninth syntax structure, when the value of the non-plane flag is 0, an operation of signaling an MPM flag required to reconstruct an intra prediction mode for a target block may be skipped. When the value of the non-plane flag is 1, an operation of signaling information related to MIP may be performed, and an operation of signaling an MPM index and an operation of signaling an MRL index may be conditionally performed.

The ninth syntax structure may correspond to a case where the ISP is not related to the MPM. According to the ninth syntax structure, the operation of signaling information relating to an ISP can be performed according to the above-described condition for signaling information relating to an ISP. The above condition may be any of the conditions described above in the other embodiments.

Fig. 72 shows a front stage of a tenth syntax structure according to the embodiment.

Fig. 73 shows a later stage of a tenth syntax structure according to the embodiment.

The tenth syntax structure may be a syntax structure corresponding to the method for signaling the pieces of information related to the intra prediction method when it is determined whether the operation of signaling the information related to the MIP is to be performed based on the MPM flag signaled with reference to fig. 52 as described above.

According to the tenth syntax structure, the MPM flag (i.e., intra _ luma _ MPM _ flag [ x0] [ y0]) may be signaled at the highest priority, and the non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be subsequently signaled.

Furthermore, according to the tenth syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]).

Furthermore, according to the tenth syntax structure, only when the value of the MPM flag is 0, an operation of signaling MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]) can be performed.

Fig. 74 shows a front stage of an eleventh syntax structure according to the embodiment.

Fig. 75 shows a later stage of an eleventh syntax structure according to the embodiment.

The eleventh syntax structure may be a syntax structure corresponding to the method for signaling pieces of information related to the intra prediction method when it is determined whether an operation of signaling information related to the MIP is to be performed based on the non-plane flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 53.

According to the eleventh syntax structure, the operation of signaling the non-plane flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]).

According to the eleventh syntax structure, an operation of signaling MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]) can be performed only when the value of the non-plane flag is 0.

Further, according to the eleventh syntax structure, when the value of the non-plane flag is 0, an operation of signaling information related to the ISP (i.e., intra _ sub _ modes _ flag [ x0] [ y0] and intra _ sub _ split _ flag [ x0] [ y0]) may not be performed.

The eleventh syntax structure may correspond to a case where the plane mode exists in the MPM list. When the value of the non-planar flag is 1, an operation of signaling the MPM flag may be skipped, and the MPM flag may be derived as 1.

When the value of the non-planar flag is 1, an operation of signaling the MPM index, an operation of signaling the MRL index, and an operation of signaling information related to the ISP may be performed. When the value of the non-planar flag is 0, the MPM flag may be signaled.

When the value of the MPM flag is 1, the intra prediction mode for the block may be derived as a planar mode, and an operation of signaling the intra prediction mode for the block may be skipped.

Fig. 76 shows a front stage of a twelfth syntax structure according to the embodiment.

Fig. 77 shows a subsequent section of a twelfth syntax structure according to the embodiment.

The twelfth syntax structure may be a syntax structure corresponding to another method for signaling pieces of information related to the intra prediction method when it is determined whether an operation of signaling information related to the MIP is to be performed based on the non-plane flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 54.

According to the twelfth syntax structure, the operation of signaling the non-plane flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]).

Further, according to the twelfth syntax structure, only when the value of the non-plane flag is 0, the operation of signaling the MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]) can be performed.

Further, according to the twelfth syntax structure, when the value of the non-plane flag is 0, an operation of signaling information related to the ISP (i.e., intra _ sub _ modes _ flag [ x0] [ y0] and intra _ sub _ split _ flag [ x0] [ y0]) may not be performed.

Fig. 78 shows a front stage of a thirteenth syntax structure according to the embodiment.

Fig. 79 shows a later stage of a thirteenth syntax structure according to an embodiment.

The thirteenth syntax structure may be a syntax structure corresponding to another method for signaling pieces of information related to the intra prediction method when it is determined whether an operation of signaling information related to the MIP is to be performed based on the non-plane flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 55.

According to the thirteenth syntax structure, the operation of signaling the non-planar flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be performed at a higher priority than signaling the MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]), signaling the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0]), and signaling the ISP-related information (i.e., intra _ sub _ partitionings _ mode _ flag [ x0] [ y0] and intra _ sub _ partitionings _ flag [ x0] [ y0 ]).

According to the thirteenth syntax structure, only when the value of the non-planar flag is 1, an operation of signaling information related to MIP, an operation of signaling information related to MRL, an operation of signaling information related to MPM, and an operation of signaling information related to ISP can be performed.

The thirteenth syntax structure may correspond to a case where the plane mode does not exist in the MPM list. When the value of the non-plane flag is 0, an operation of signaling an MPM flag required to reconstruct an intra prediction mode for a target block may be skipped. When the value of the non-plane flag is 1, an operation of signaling information related to MIP may be performed, and an operation of signaling an MPM index, an operation of signaling an MRL index, and an operation of signaling information related to ISP may be conditionally performed.

When the value of the non-flat flag is 0, an operation of signaling information related to the ISP may not be performed.

Fig. 80 shows a front stage of a fourteenth syntax structure according to an embodiment.

Fig. 81 shows a later stage of a fourteenth syntax structure according to the embodiment.

The fourteenth syntax structure may be a syntax structure corresponding to the method for signaling pieces of information related to the intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on the MPM flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 56.

According to a fourteenth syntax structure, the MPM flag (i.e., intra _ luma _ MPM _ flag [ x0] [ y0]) may be signaled at the highest priority, and the non-plane flag (i.e., intra _ luma _ not _ planar _ flag [ x0] [ y0]) may be subsequently signaled.

According to the fourteenth syntax structure, the operation of signaling the non-plane flag (i.e., intra _ luma _ not _ planar _ flag x0] [ y0]) may be performed at a higher priority than the signaling of the MRL index (i.e., intra _ luma _ ref _ idx [ x0] [ y0 ]).

Further, according to the fourteenth syntax structure, only when the value of the MPM flag is 0, an operation of signaling MIP-related information (i.e., intra _ MIP _ flag [ x0] [ y0] and intra _ MIP _ mode [ x0] [ y0]) can be performed.

Further, according to the fourteenth syntax structure, when the value of the non-plane flag is 0, an operation of signaling information related to the ISP (i.e., intra _ sub _ modes _ flag [ x0] [ y0] and intra _ sub _ split _ flag [ x0] [ y0]) may not be performed.

Signaling structure of multiple pieces of information based on signaling method

In the following figures indicating the signaling structure, the leftmost column indicates pieces of information as targets to be signaled. The top row indicates the condition. From each condition, it may be determined whether corresponding information is to be signaled. In other words, the description of the signaling of the information written in (column x, row y) of each table may indicate whether the information in (column 1, row y) is to be signaled when the condition in (column x, row 1) is satisfied. Each of x and y may be 2 or greater.

Fig. 82 illustrates a first signaling structure according to an embodiment.

The first signaling structure may be a signaling structure corresponding to a method for signaling pieces of information related to an intra prediction method as described above with reference to fig. 34.

The first signaling structure may be a signaling structure including the method for setting the plane mode to be unavailable according to the application of the ISP as described above with reference to fig. 26.

According to the first signaling structure, when the value of the ISP flag is 1, the plane mode may be set to be unavailable. When the value of the ISP flag is 1, the value of the non-planar flag is set to 1, and thus an operation of signaling the non-planar flag may be skipped.

When the first signaling structure is used, if the value of the MIP flag is 1, intra prediction for a block may be performed using MIP and an operation of signaling pieces of information related to other intra prediction methods may be skipped.

Fig. 83 shows a second signaling structure according to the embodiment.

The second signaling structure may be a signaling structure corresponding to a method for signaling pieces of information related to the intra prediction method when the non-planar flag is preferentially signaled as described above with reference to fig. 39.

According to a second signaling structure, the MIP flag may be signaled with the highest priority, and then the non-planar flag may be signaled when the value of the MIP flag is 0.

The case where the value of the non-plane flag is 0 may indicate that the plane mode is an intra prediction mode for the target block. In case that the value of the MRL index is greater than 0, the planar mode is not available, and thus when the value of the non-planar flag is 0, the MRL index may be derived as 0, and an operation of signaling the MRL index may be skipped.

Furthermore, since the plane mode is determined as the intra prediction mode for the target block, an operation of signaling information related to the MPM may also be skipped.

When the second signaling structure is used, if the value of the MIP flag is 1, intra prediction for a block may be performed using MIP and an operation of signaling pieces of information related to other intra prediction methods may be skipped.

Fig. 84 shows a third signaling structure according to an embodiment.

The third signaling structure may be a signaling structure corresponding to another method for signaling pieces of information related to the intra prediction method when the non-planar flag is preferentially signaled as described above with reference to fig. 40.

The third signaling structure may indicate whether a plurality of pieces of information such as flags and indexes are to be signaled and which values are set to the information when the non-planar flag is preferentially signaled.

The planar mode may be the most frequently used intra prediction mode among all intra prediction modes. Therefore, it may be beneficial to signal the information related to the planar mode first.

In the embodiment described above with reference to fig. 22, when the value of the MIP flag is 1, the non-planar flag may not be signaled and may be set to 0 (as a default value).

The case where the value of the non-planar flag is 1 may indicate that the value of the MIP flag is 0. Therefore, according to the third signaling configuration on the premise that the non-plane flag is signaled with priority, when the value of the non-plane flag is 1, the operation of signaling the MIP flag can be skipped.

The non-plane flag may be information indicating whether a plane mode is to be used in the MPM. Based on these characteristics, non-planar landmarks may be closely tied to the MPM.

In the embodiment and the like described above with reference to fig. 22, when the value of the MPM flag is 1, a non-plane flag may be signaled, and the non-plane flag may be used to indicate whether a plane mode is to be used in intra prediction using MPM.

When the non-plane flag is signaled using the correlation priority between the non-plane flag and the MPM flag, the use of the MPM may be fixed when it is determined whether a specific intra prediction method is to be performed based on the non-plane flag. Here, according to a predefined scheme, the value of the non-plane flag may be used to determine whether a specific intra prediction method is to be performed.

When the value of the non-plane flag is 1, an MPM using an intra prediction mode other than the plane mode may be determined as an intra prediction method for a block. When the value of the non-plane flag is 0, the intra prediction method for the block is not specified, and thus the MPM flag may be additionally signaled.

When the value of the non-plane flag is 1, an MPM using an intra prediction mode other than the plane mode may be used as an intra prediction method for a block. That is, when the value of the non-planar flag is 1, it may be determined whether MPM will be used. Accordingly, when the value of the non-planar flag is 1, the operation of signaling the MPM flag may be skipped.

When the value of the non-plane flag is 0, an intra prediction method for a block may not be specified. Accordingly, an MPM flag may be additionally signaled, and an intra prediction method to be used for a block may be checked by signaling the MPM flag. When the value of the non-plane flag is 0, an MPM flag may be signaled, and when the value of the MPM flag is 1, MPM using a plane mode may be used as an intra prediction method for a block. In contrast, when the value of the non-plane flag is 0 and the value of the MPM flag is 0, an intra prediction method using an intra prediction mode that is not included in the MPM list may be used for the block.

A method opposite to the method corresponding to the third signaling structure may be used. When the value of the non-plane flag is 0, the MPM using the plane mode may be determined as an intra prediction method for a block. When the value of the non-plane flag is 1, an intra prediction method for a block is not specified, and thus an MPM flag may be additionally signaled. When the value of the non-plane flag is 0, MPM using a plane mode may be used as an intra prediction method for a block. That is, when the value of the non-planar flag is 0, it may be determined whether MPM will be used. Accordingly, when the value of the non-planar flag is 0, the operation of signaling the MPM flag may be skipped. When the value of the non-plane flag is 1, an intra prediction method for a block may not be specified. Accordingly, an MPM flag may be additionally signaled, and an intra prediction method to be used for the block may be checked by signaling the MPM flag. When the value of the non-plane flag is 1, an MPM flag may be signaled, and when the value of the MPM flag is 1, an MPM using another intra prediction mode other than the plane mode may be used as an intra prediction method for a block. In contrast, when the value of the non-plane flag is 1 and the value of the MPM flag is 0, an intra prediction method using an intra prediction mode that is not included in the MPM list may be used for the block.

According to a third signaling structure, the planar mode may be unavailable when the value of the MRL index is greater than 0. Therefore, as described above in the third signaling structure, the case where the value of the non-plane flag is 0 indicates that the plane mode is used, and thus when the value of the non-plane flag is 0, the value of the MRL index may be set to 0, and the operation of signaling the MRL index may be skipped.

The case where the value of the non-plane flag is 0 may indicate that the plane mode is an intra prediction mode for the block. Accordingly, as described above with respect to the third signaling structure, when the value of the non-plane flag is 0, an operation of signaling an MPM flag to be used for reconstructing an intra prediction mode for a block may be skipped.

When the value of the non-flat flag is 1, only the MRL index and the ISP flag may be signaled in the worst case. When the value of the non-planar tag is 0, only the MIP tag and the ISP tag may be signaled in the worst case.

The operation of signaling the MPM flag may always be skipped regardless of the value of the non-planar flag. Furthermore, a maximum of two messages may be signaled regardless of the value of the non-flat flag. Here, the information may include a flag and an index. The signaling method corresponding to the third signaling structure may be more efficient than the signaling method described above with reference to fig. 22 and the like because only two pieces of information at most are signaled.

Further, as described above in the embodiments, when the plane mode is set to be unavailable in the sub-partition mode such as the ISP, the value of the ISP flag may be set to 0 when the value of the non-plane flag is 1, and the operation of signaling the ISP flag may be skipped.

Fig. 85 shows a fourth signaling structure according to an embodiment.

The fourth signaling structure may be a signaling structure corresponding to the method for signaling pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled and the plane mode is not available in the MRL as described above with reference to fig. 44.

According to a fourth signaling structure, the MIP flag may be signaled with the highest priority. When the value of the MIP flag is 0, the non-planar flag may then be signaled. The case where the value of the non-plane flag is 0 may indicate that the plane mode is an intra prediction mode for the target block.

According to the embodiment described above with reference to fig. 44, the planar mode may not be available in the ISP. Accordingly, when the value of the MIP flag is 0 and the value of the non-planar flag is 0, the ISP flag may be derived as 0 and the operation of signaling the ISP flag may be skipped.

According to the fourth signaling structure, when the value of the non-plane flag is 0, the MRL index may also be derived as 0, and an operation of signaling the MRL index may be skipped. Further, when the value of the non-planar flag is 0, the operation of signaling the MPM flag may be skipped. Accordingly, when the value of the MIP flag is 0 and the value of the non-planar flag is 0, an operation of signaling the MRL index, an operation of signaling the ISP flag, and an operation of signaling the MPM flag may be skipped.

When the fourth signaling structure is used, if the value of the MIP flag is 1, intra prediction for a block may be performed using MIP and an operation of signaling pieces of information related to other intra prediction methods may be skipped.

Fig. 86 illustrates a fifth signaling structure according to an embodiment.

The fifth signaling structure may be a signaling structure corresponding to the method for signaling the pieces of information related to the intra prediction method when it is determined whether the information related to the MIP is to be signaled based on the non-planar flag signaled with priority as described above with reference to fig. 50.

According to a fifth signaling structure, the non-planar flag is signaled first, and the MIP flag may be derived as 0 when the value of the non-planar flag is 1. Thus, the operation of signaling the MIP flag may be skipped.

According to the fifth signaling structure, when the value of the non-plane flag is 0, the MRL index may be derived as 0. Thus, the operation of signaling the MRL index may be skipped.

According to the fifth signaling structure, when the value of the non-plane flag is 0, an operation of signaling an MPM flag required for deriving an intra prediction mode may be skipped.

Fig. 87 shows a sixth signaling structure according to an embodiment.

The sixth signaling structure may be a signaling structure corresponding to the method for signaling pieces of information related to the intra prediction method when it is determined whether an operation of signaling information related to the MIP is to be performed based on the non-plane flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 53.

According to a sixth signaling structure, the non-planar flag may be preferentially signaled. When the value of the non-planar flag is 1, the value of the MIP flag may be derived as 0. Thus, the operation of signaling the MIP flag may be skipped. When the value of the non-plane flag is 0, intra prediction for the target block is performed using the plane mode, and thus the MRL index may be derived as 0, and an operation of signaling the MRL index may be skipped.

In the embodiment described above with reference to fig. 53, the planar mode may not be available in the ISP. Therefore, when the value of the non-planar flag is 0, the ISP flag may also be derived as 0, and the operation of signaling the ISP flag may be skipped. In addition, when the value of the non-planar flag is 0, the operation of signaling the MPM flag may also be skipped.

Therefore, according to the sixth signaling structure, when the value of the non-planar flag is 1, signaling of three pieces of information (such as the MRL index, the ISP flag, and the MPM flag) can be performed in the worst case. When the value of the non-planar flag is 1, the operation of signaling the MIP flag may be always skipped. When the value of the non-planar flag is 0, only the MIP flag can be signaled, and the total number of bits to be signaled can be greatly reduced by such a signaling structure.

Fig. 88 shows a seventh signaling structure according to the embodiment.

The seventh signaling structure may be a signaling structure corresponding to the method for signaling pieces of information related to the intra prediction method when the MPM flag is preferentially signaled as described above with reference to fig. 46.

According to the seventh signaling structure, the MPM flag may be signaled when the value of the MIP flag is 0. When the value of the MPM flag is 1, the non-planar flag may be always signaled.

In the seventh signaling structure, the following conditions may be added to the sixth signaling structure: for the MRL index, when the value of the non-flat flag is 0, the operation of signaling the MRL index is skipped. Further, the following conditions may be added: for the ISP flag, when the value of the non-flat flag is 0, the operation of signaling the ISP flag is skipped.

When the value of the MRL index is greater than 0, the MPM list may always be referred to. Therefore, in the seventh signaling structure, when the value of the MPM flag is 0, the MRL index may always be derived as 0, and an operation of signaling the MRL index may be skipped.

When the seventh signaling structure is used, if the value of the MIP flag is 1, intra prediction for a block may be performed using MIP and an operation of signaling pieces of information related to other intra prediction methods may be skipped.

Fig. 89 shows an eighth signaling structure according to the embodiment.

The eighth signaling structure may be a signaling structure corresponding to the method for signaling the pieces of information related to the intra prediction method when it is determined whether the information related to the MIP is to be signaled based on the MPM flag signaled preferentially as described above with reference to fig. 52.

In the embodiment and the like described above with reference to fig. 22, when the value of the MIP flag is 1, the MPM flag may not be signaled. The relationship between the MIP flag and the MPM flag may indicate that the MPM flag 1 (signaled) corresponds to MIP flag 0. Therefore, in the eighth signaling structure, when the value of the MPM flag is 1, the operation of signaling the MIP flag may be skipped.

According to the eighth signaling structure, when the value of the MPM flag is 1, the MRL index may be signaled, and when the value of the MRL index is greater than 0, an operation of signaling the ISP flag may be skipped. Further, when the value of the MRL index is greater than 0, the planar mode is not available, and thus the value of the non-planar flag may be set to 1, and an operation of signaling the non-planar flag may be skipped.

When the value of the MRL index is greater than 0, the value of the MPM flag may always be 1. Accordingly, when the value of the MPM flag is 0, the MRL index may be derived as 0, and an operation of signaling the MRL index may be skipped.

Since the non-planar flag is signaled only when the value of the MPM flag is 1, the operation of signaling the non-planar flag may be skipped when the value of the MPM flag is 0.

When the value of the MPM flag is 1, signaling three pieces of information (such as an MRL index, an ISP flag, and a non-plane flag) can be performed in the worst case. Signaling two pieces of information (such as the MIP flag and the ISP flag) may be performed when the value of the MPM flag is 0. That is, in the eighth signaling structure, a smaller number of pieces of information can be signaled even in the worst case, as compared with the signaling structure in which the MIP flag is signaled first as in the case of the embodiment described above with reference to fig. 22 and 24. Therefore, the number of bits to be signaled may be reduced by the eighth signaling structure, and the eighth signaling structure may be considered a more efficient signaling structure.

Fig. 90 shows a ninth signaling structure according to an embodiment.

The ninth signaling structure may be a signaling structure corresponding to the method for signaling pieces of information related to the intra prediction method when it is determined whether an operation of signaling information related to the MIP will be performed based on the MPM flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 56.

According to the ninth signaling structure, when the value of the signaled MPM flag is 1, the MIP flag may be derived to be 0, and an operation of signaling the MIP flag may be skipped.

In the ninth signaling structure, the following condition may be added to the eighth signaling structure: for the MRL index, when the value of the non-flat flag is 0, the operation of signaling the MRL index is skipped. In addition, the following conditions may be further added: for the ISP flag, when the value of the non-flat flag is 0, the operation of signaling the ISP flag is skipped.

According to the embodiment described above with reference to fig. 56, when the value of the MRL index is greater than 0, the value of the MPM flag may always be 1. Therefore, in the ninth signaling structure, when the value of the MPM flag is 0, the MRL index may be derived as 0, and an operation of signaling the MRL index may be skipped.

Fig. 91 shows a tenth signaling structure according to the embodiment.

The tenth signaling structure may be a signaling structure corresponding to the method for signaling pieces of information related to the intra prediction method when the MPM flag is preferentially signaled as described above with reference to fig. 46. From this point of view, the tenth signaling structure may be similar to the seventh signaling structure previously described. However, in the tenth signaling structure, the plane mode may not be included in the MPM list.

According to the tenth signaling structure, when the value of the MIP flag is 0, the MPM flag may be signaled. When the value of the MPM flag is 1, the non-planar flag may be always signaled.

In the tenth signaling structure, the following conditions may be added to the sixth signaling structure: for the MRL index, when the value of the non-flat flag is 0, the operation of signaling the MRL index is skipped. Further, the following conditions may be added: for the ISP flag, when the value of the non-flat flag is 0, the operation of signaling the ISP flag is skipped.

When the value of the MRL index is greater than 0, the MPM list may always be referred to. Therefore, in the tenth signaling structure, when the value of the MPM flag is 0, the MRL index may always be derived as 0, and an operation of signaling the MRL index may be skipped.

When the value of the MPM flag is 0, the non-planar flag may be always signaled.

The case where the value of the non-plane flag is 0 may indicate that the plane mode is an intra prediction mode for the target block. Therefore, in the tenth signaling structure, the following conditions may be further added to the seventh signaling structure: for the ISP flag, when (the value of the MPM flag is 0 and) the value of the non-planar flag is 0, the operation of signaling the ISP flag is skipped.

When the tenth signaling structure is used, if the value of the MIP flag is 1, intra prediction for a block may be performed using MIP and an operation of signaling pieces of information related to other intra prediction methods may be skipped.

Fig. 92 shows an eleventh signaling structure according to an embodiment.

The eleventh signaling structure may be a signaling structure corresponding to the method for signaling pieces of information related to the intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on the MPM flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 56. From this point of view, the eleventh signaling structure may be similar to the aforementioned ninth signaling structure. However, in the eleventh signaling structure, the plane mode may not be included in the MPM list.

According to the eleventh signaling structure, when the value of the signaled MPM flag is 1, the MIP flag may be derived as 0, and an operation of signaling the MIP flag may be skipped.

In the eleventh signaling structure, the following conditions may be added to the eighth signaling structure: for the MRL index, when the value of the non-flat flag is 0, the operation of signaling the MRL index is skipped. Further, the following conditions may be added: for the ISP flag, when the value of the non-flat flag is 0, the operation of signaling the ISP flag is skipped.

The case where the value of the non-plane flag is 0 may indicate that the plane mode is an intra prediction mode for the target block. Therefore, in the eleventh signaling structure, the following conditions may be further added to the eighth signaling structure: for the ISP flag, when (the value of the MPM flag is 0 and) the value of the non-planar flag is 0, the operation of signaling the ISP flag is skipped.

Further, according to the eleventh signaling structure, when the value of the MPM index is greater than 0, the value of the MPM flag may always be 1. Accordingly, when the value of the MPM flag is 0, the MRL index may be derived as 0, and an operation of signaling the MRL index may be skipped.

Apparatus for performing the method in the embodiments

Fig. 93 illustrates a configuration of an intra prediction unit according to an embodiment.

The intra prediction unit 9300 may include an intra prediction operation unit 9310, an intra prediction mode information signaling unit 9320, and a residual signal transformation unit 9330.

The intra prediction unit 9300 may correspond to the intra prediction unit 120 of the encoding apparatus 100 and the intra prediction unit 240 of the decoding apparatus 200. In other words, the intra prediction unit 9300 may be the intra prediction unit 120 and/or the intra prediction unit 240 performing the methods in the foregoing embodiments.

The intra prediction execution unit 9310 may perform intra prediction.

The intra prediction mode information signaling unit 9320 may perform an operation of signaling prediction information.

The prediction information may include a plurality of pieces of information signaled with respect to the above-described intra prediction. For example, the prediction information may be an ISP flag, an ISP mode, the number of ISPs, an MRL flag, an MRL index, an MIP flag, an MIP mode, an MPM flag, an MPM index, a non-flat flag, and the like. Further, the prediction information may include additional information for intra prediction described in the embodiments, in addition to the above information.

In the encoding apparatus 100, the intra prediction mode information signaling unit 9320 may add information described as signaled in the embodiment to a bitstream.

In the decoding apparatus 200, the intra prediction mode information signaling unit 9320 may extract and acquire information described as signaled in the embodiment from a bitstream.

The residual signal transform unit 9330 may perform transform on a residual signal (i.e., a residual block) acquired after prediction for the target block. The residual signal transforming unit 9330 may be included in each of the transforming unit 130 of the encoding apparatus 100 and the inverse transforming unit 230 of the decoding apparatus 200.

In the decoding apparatus 200, the residual signal transform unit 9330 may not be present. Alternatively, in the decoding apparatus 200, the residual signal transforming unit 9330 may generate a reconstructed residual block by performing an inverse transform on the inversely quantized coefficients.

Fig. 94 illustrates a configuration of an intra prediction execution unit according to an embodiment.

The intra prediction execution unit 9310 may include a sub partition flag checking unit 9410, an intra prediction execution condition search unit 9420, and an intra prediction execution unit 9430.

The sub-partition flag checking unit 9410 may check a flag associated with a sub-partition.

The intra prediction operation condition search unit 9420 may check an operation condition regarding whether intra prediction is to be performed according to the checked value of the flag related to the sub-partition.

The intra prediction execution unit 9430 may perform intra prediction that coincides with the condition determined by the intra prediction operation condition search unit 9420.

Configuration of intra prediction mode information signaling unit

In the following drawings showing the configuration of the intra prediction mode information signaling unit 9320, a rectangle may indicate the name of a subcomponent of the intra prediction mode information signaling unit 9320.

The arrows starting from each rectangle may indicate that output from the sub-component is sent.

The arrow from the first rectangle to the second rectangle may indicate that the second sub-assembly indicated by the second rectangle performs signaling after the first sub-assembly indicated by the first rectangle has performed signaling.

A circle to which an arrow from a rectangle extends may indicate a switch. In the lower left or upper right part of each switch, there may be a rectangle connected to a circle. Further, a rectangle connected to a circle may be present at the lower right of the switch. The diagonal line connected to the circle to which the arrow extends may be connected to the lower left, upper right or lower right circle.

Each switch may provide selective connections between the subassemblies.

The sub-assembly indicated by the rectangle may be connected to one of the sub-assembly indicated by the rectangle connected to the lower left or upper right circle of the sub-assembly and the sub-assembly indicated by the rectangle connected to the lower right circle of the sub-assembly by a switch connected to the sub-assembly itself. The diagonal of each switch may indicate such selective connection, and may indicate which sub-components are to be connected through the corresponding switch.

The fact that two sub-assemblies are connected to each other by a switch may represent: after the operation (e.g., signaling) of the first sub-component indicated by the first rectangle has been performed, the operation (e.g., signaling) of the second sub-component indicated by the second rectangle is performed. Here, an arrow from the first rectangle may be connected to a first end of the switch. The second rectangle may be one of two rectangles respectively connected to two circles, wherein the two circles may be connected to the second end of the switch.

The first subcomponent may signal specific information. For example, when the specific information signaled by the first upper subassembly is 0, the switch may be connected to the lower left circle or the upper right circle. When the specific information signaled by the first sub-assembly is 1, the switch may be connected to the lower right circle.

Accordingly, when the first specific information is signaled from the first sub-assembly and the first specific information is 0, the second specific information may be signaled from the second sub-assembly connected to the lower left circle or the upper right circle. When the first specific information is signaled from the upper sub-assembly and the first specific information is 1, the third specific information may be signaled from the third sub-assembly connected to the lower right circle. Here, the specific information signaled from the first sub-component may be a result of a determination performed by the first sub-component, or may be a flag for a specific intra prediction method among pieces of information signaled from the first sub-component.

Subcomponents of the intra prediction mode information signaling unit 9320 may include: 1) a MIP tag signaling unit for performing an operation of signaling the MIP tag; 2) a MIP mode signaling unit for performing an operation of signaling a MIP mode; 3) an MRL signaling unit for performing an operation of signaling information related to the MRL (such as an MRL index); 4) an ISP signaling determination unit for checking a condition related to an operation of signaling ISP-related information; 5) an ISP signaling unit for performing an operation of signaling information (such as an ISP flag and an ISP mode) related to the ISP; 6) an MPM signaling determination unit for checking a condition related to an operation of signaling information related to an MPM; 7) an MPM flag signaling unit for performing an operation of signaling an MPM flag; 8) a non-MPM intra prediction mode setting unit for performing setting (or reconstruction of a block) for the block using the signaled intra prediction mode among the remaining modes when the intra prediction method for the block is non-MPM (i.e., when a value of the MPM flag is 0); 9) a non-planar flag signaling determination unit for checking a condition related to an operation of signaling a non-planar flag; 10) a non-planar flag signaling unit for performing an operation of signaling a non-planar flag; 11) an MPM index signaling unit for performing an operation of signaling an MPM index; 12) an intra prediction mode setting unit for setting an intra prediction mode for a block; and the like.

Subcomponents of the intra prediction mode information signaling unit 9320 and connection relationships defined by arrows and switches between the subcomponents are illustrated in detail in the following drawings indicating the configuration of the intra prediction mode information signaling unit 9320.

Fig. 95 illustrates a first configuration of an intra prediction mode information signaling unit according to an embodiment.

The first configuration of the intra prediction mode information signaling unit 9320 may indicate the configuration of the intra prediction mode information signaling unit 9320 for performing the embodiment described above with reference to fig. 22.

The configuration for performing the embodiment described above with reference to fig. 22 may be a basic configuration of each of the intra prediction execution unit 9310, the intra prediction mode information signaling unit 9320, the residual signal transformation unit 9330, the sub-partition flag checking unit 9410, the intra prediction execution condition search unit 9420, and the intra prediction execution unit 9330.

For example, the first configuration of the intra prediction mode information signaling unit 9320 shown in fig. 95 may be a basic configuration of the intra prediction mode information signaling unit 9320.

Fig. 96 illustrates a second configuration of an intra prediction mode information signaling unit according to an embodiment.

The second configuration of the intra prediction mode information signaling unit 9320 may indicate the configuration of the intra prediction mode information signaling unit 9320 for performing the method for signaling pieces of information related to the intra prediction method described above with reference to fig. 34.

In order to perform the method for signaling pieces of information related to the intra prediction method described above with reference to fig. 34, a partial modification may be applied to the intra prediction operation unit 9310 and the intra prediction mode information signaling unit 9320.

In the intra prediction execution unit 9310, the sub-partition flag checking unit 9410 may check a value of the sub-partition flag. In the case where the value of the sub-partition flag is 1, when the intra prediction mode for the block is a specific intra prediction mode, the intra prediction operation condition search unit 9420 may determine that a condition related to the operation of intra prediction is not satisfied, and may not perform intra prediction. Here, the specific intra prediction mode may be an intra prediction mode set to be unavailable for sub-partitions as described in the above embodiments, for example, a planar mode, a DC mode, a wide angle mode, an even-numbered angle mode, and an odd-numbered angle mode.

In the second configuration of the intra prediction mode information signaling unit 9320, 1) the sub-partition may be an ISP, and 2) the plane mode may be a specific intra prediction mode that is not available for the sub-partition.

According to the second configuration of the intra prediction mode information signaling unit 9320, the intra prediction mode information signaling unit 9320 may additionally include the following configurations: the allowed non-planar flag signaling determination unit determines whether the non-planar flag is to be signaled based on a value of the ISP flag.

In addition to ISPs, sub-partitions can also be applied to other types of partitions. Also, another intra prediction mode other than the planar mode may be set to a specific prediction mode that is not available for the sub-partition.

In the second configuration of the intra prediction mode information signaling unit 9320, the order of the operation of signaling the information related to the MRL, the operation of signaling the information related to the ISP, and the operation of signaling the information related to the MPM may be configured differently from the configuration shown in fig. 96. In addition, some subcomponents may be added and/or removed.

Fig. 97 illustrates a third configuration of an intra prediction mode information signaling unit according to an embodiment.

The third configuration of the intra prediction mode information signaling unit 9320 may indicate the configuration of the intra prediction mode information signaling unit 9320 for performing another method for signaling pieces of information related to an intra prediction method when the non-plane flag is preferentially signaled as described above with reference to fig. 40.

In order to perform another method for signaling pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled as described above with reference to fig. 40, partial modification may be applied to the intra prediction operation unit 9310 and the intra prediction mode information signaling unit 9320.

In the third configuration of the intra prediction mode information signaling unit 9320, the non-plane flag signaling determination unit may be removed. Further, the operation of signaling the non-planar flag may be performed at a higher priority than signaling the information related to the MRL, signaling the information related to the MPM, and signaling the information related to the ISP.

The MIP flag signaling unit may signal one of the MIP mode and the non-planar flag according to a value of the MIP flag.

In the third configuration of the intra prediction mode information signaling unit 9320, the planar mode may be unavailable when the value of MRL is greater than 0. Accordingly, the intra prediction mode information signaling unit 9320 may additionally comprise a plane mode based signaling determination unit for determining whether an operation of signaling MRL related information will be performed according to the value of the non-plane flag.

According to the third configuration of the intra prediction mode information signaling unit 9320, the intra prediction related mode signaling determining unit may determine whether an operation of signaling MRL related information will be performed by the MRL signaling unit. However, in practice, the intra prediction related mode signaling determination unit may also determine another intra prediction mode that always uses the planar mode or is unavailable using the planar mode.

In addition to ISPs, sub-partitions can also be applied to other types of partitions.

In the third configuration of the intra prediction mode information signaling unit 9320, an operation of signaling information related to MRL, an operation of signaling information related to ISP, and an operation of signaling information related to MPM may be configured differently from the configuration shown in fig. 96. In addition, some subcomponents may be added and/or removed.

Fig. 98 illustrates a fourth configuration of an intra prediction mode information signaling unit according to an embodiment.

The fourth configuration of the intra prediction mode information signaling unit 9320 may indicate a configuration of the intra prediction mode information signaling unit 9320 for performing the method for signaling the pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled and the plane mode is not available in the MRL as described above with reference to fig. 45.

In order to perform the method for signaling pieces of information related to the intra prediction method when the non-plane flag is preferentially signaled and the plane mode is not available in the MRL as described above with reference to fig. 45, a partial modification may be applied to the intra prediction execution unit 9310 and the intra prediction mode information signaling unit 9320.

In the intra prediction execution unit 9310, the sub-partition flag checking unit 9410 may check a value of the sub-partition flag. In the case where the value of the sub-partition flag is 1, when the intra prediction mode for the block is a specific intra prediction mode, the intra prediction operation condition search unit 9420 may determine that a condition related to the operation of intra prediction is not satisfied, and may not perform intra prediction. Here, the specific intra prediction mode may be an intra prediction mode set to be unavailable for sub-partitions described in the above embodiments, for example, a planar mode, a DC mode, a wide angle mode, an even-numbered angle mode, and an odd-numbered angle mode.

In the fourth configuration of the intra prediction mode information signaling unit 9320, 1) a sub-partition may be an ISP, and 2) a plane mode may be a specific intra prediction mode that is not available for the sub-partition.

The fourth configuration of the intra prediction mode information signaling unit 9320 may be a configuration that exemplifies a planar mode as a specific intra prediction mode that is not available for a sub-partition. Unlike the fourth configuration of the intra prediction mode information signaling unit 9320, another intra prediction mode other than the planar mode may be set to a specific intra prediction mode that is not available for the sub-partition.

In the fourth configuration of the intra prediction mode information signaling unit 9320, the non-plane flag signaling determination unit may be removed. Further, the operation of signaling the non-planar flag may be performed at a higher priority than signaling the information related to the MRL, signaling the information related to the MPM, and signaling the information related to the ISP.

As described above in the third configuration of the intra prediction mode information signaling unit 9320, even in the fourth configuration of the intra prediction mode information signaling unit 9320, the MIP flag signaling unit may signal one of the MIP mode and the non-plane flag according to the value of the MIP flag.

In the fourth configuration of the intra prediction mode information signaling unit 9320, when the value of MRL is greater than 0, the planar mode may be unavailable. Accordingly, the intra prediction mode information signaling unit 9320 may additionally include an intra prediction related mode signaling determination unit for determining whether an operation of signaling MRL related information will be performed according to the value of the non-plane flag.

According to the fourth configuration of the intra prediction mode information signaling unit 9320, the intra prediction related mode signaling determining unit may determine whether an operation of signaling the MRL related information will be performed by the MRL signaling unit. In practice, however, the intra-prediction related mode signaling determination unit may also determine another intra-prediction mode that always uses the planar mode or is unavailable using the planar mode.

Unlike the third configuration of the intra prediction mode information signaling unit 9320, the fourth configuration of the intra prediction mode information signaling unit 9320 may further include an ISP signaling determination unit by which whether an operation of signaling ISP-related information will be performed may be determined based on a value determined by the intra prediction related mode signaling determination unit. Such an operation may be an operation reflecting the following condition: when the value of the non-flat flag is 0, the ISP is not available. When the value of the non-plane flag is 0, the intra prediction mode setting unit may set the plane mode as the intra prediction mode for the target block. Since the planar mode is used, the value of the MRL index may be set to 0, and the value of the ISP flag may be set to 0. Furthermore, the MRL index and ISP flag may not be signaled separately. Further, when the value of the non-plane flag is 0, the plane mode is determined as the intra prediction mode for the block, and thus an operation of signaling information related to the MPM may also be skipped.

In addition to ISPs, sub-partitions may also be applied to other types of partitions. Also, another intra prediction mode other than the planar mode may be set to a specific prediction mode that is not available for the sub-partition.

In the fourth configuration of the intra prediction mode information signaling unit 9320, the order of the operation of signaling the information related to the MRL, the operation of signaling the information related to the ISP, and the operation of signaling the information related to the MPM may be configured differently from the configuration shown in fig. 98. In addition, some subcomponents may be added and/or removed.

Fig. 99 shows a fifth configuration of an intra prediction mode information signaling unit according to an embodiment.

The fifth configuration of the intra prediction mode information signaling unit 9320 may indicate the configuration of the intra prediction mode information signaling unit 9320 for performing the method for signaling the pieces of information related to the intra prediction method when the MPM flag is preferentially signaled as described above with reference to fig. 46.

Unlike the above-described fourth configuration of the intra prediction mode information signaling unit 9320, in the fifth configuration of the intra prediction mode information signaling unit 9320, the position of the MPM flag signaling unit may be changed. By this change, the operation of signaling the MPM flag can be performed with higher priority than the signaling of the non-planar flag.

For other conditions and operations, the description regarding the fourth configuration of the intra prediction mode information signaling unit 9320 may also be applied to the fifth configuration of the intra prediction mode information signaling unit 9320.

Fig. 100 shows a sixth configuration of an intra prediction mode information signaling unit according to an embodiment.

A sixth configuration of the intra prediction mode information signaling unit 9320 may indicate a configuration of the intra prediction mode information signaling unit 9320 for performing a method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on a non-plane flag signaled by priority as described above with reference to fig. 50.

Unlike the above-described third configuration of the intra prediction mode information signaling unit 9320, in the sixth configuration of the intra prediction mode information signaling unit 9320, it may be determined to signal the MPM flag after signaling the non-plane flag. In the sixth configuration of the intra prediction mode information signaling unit 9320, it may be determined whether an operation of signaling the MIP flag will be performed based on the value of the non-plane flag.

For other conditions and operations, the description made with respect to the third configuration of the intra prediction mode information signaling unit 9320 may also be applied to the sixth configuration of the intra prediction mode information signaling unit 9320.

Fig. 101 illustrates a seventh configuration of an intra prediction mode information signaling unit according to an embodiment.

The seventh configuration of the intra prediction mode information signaling unit 9320 may indicate the configuration of the intra prediction mode information signaling unit 9320 for performing another method for signaling pieces of information related to an intra prediction method when it is determined whether an operation of signaling information related to MIP is to be performed based on the non-plane flag signaled by priority as described above with reference to fig. 51.

In the seventh configuration of the intra prediction mode information signaling unit 9320, one of the MIP flag and the MRL related information may be signaled according to a value of the non-plane flag.

In the seventh configuration of the intra prediction mode information signaling unit 9320, when the value of the non-plane flag is 0, all of the operation of signaling the information related to the MIP, the operation of signaling the information related to the MRL, and the operation of signaling the information related to the MPM may be skipped. When the value of the non-plane flag is 1, an operation of signaling information related to MIP, an operation of signaling information related to MRL, and an operation of signaling information related to MPM may be performed.

In the seventh configuration of the intra prediction mode information signaling unit 9320, the operation of signaling the information related to the ISP may be performed according to a previous condition irrespective of the value of the non-plane flag.

For other conditions and operations, the description about the sixth configuration of the intra prediction mode information signaling unit 9320 can also be applied to the seventh configuration of the intra prediction mode information signaling unit 9320.

Fig. 102 shows an eighth configuration of an intra prediction mode information signaling unit according to an embodiment.

The eighth configuration of the intra prediction mode information signaling unit 9320 may indicate a configuration of the intra prediction mode information signaling unit 9320 for performing the method for signaling the plurality of pieces of information related to the intra prediction method when it is determined whether the operation of signaling the information related to the MIP is to be performed based on the MPM flag signaled preferentially as described above with reference to fig. 52.

Unlike the above-described sixth configuration of the intra prediction mode information signaling unit 9320, in the eighth configuration of the intra prediction mode information signaling unit 9320, the position of the MPM flag signaling unit may be changed. By this change, the operation of signaling the MPM flag can be performed with higher priority than the signaling of the non-planar flag. Further, whether the MIP flag will be signaled may be determined according to the value of the MPM flag other than the non-planar flag.

For other conditions and operations, the description regarding the sixth configuration of the intra prediction mode information signaling unit 9320 may also be applied to the eighth configuration of the intra prediction mode information signaling unit 9320.

Fig. 103 illustrates a ninth configuration of an intra prediction mode information signaling unit according to an embodiment.

The ninth configuration of the intra prediction mode information signaling unit 9320 may indicate a configuration of the intra prediction mode information signaling unit 9320 for performing the method for signaling the pieces of information related to the intra prediction method when it is determined whether the operation of signaling the information related to the MIP is to be performed based on the non-plane flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 53.

The ninth configuration of the intra prediction mode information signaling unit 9320 may be realized by combining the above-described fourth configuration of the intra prediction mode information signaling unit 9320 with the sixth configuration of the intra prediction mode information signaling unit 9320.

According to the ninth configuration of the intra prediction mode information signaling unit 9320, one of the MIP-related information and the MRL-related information may be signaled according to a value of the non-plane flag. When the value of the non-plane flag is 0, an operation of signaling information related to MIP may be performed, and all of an operation of signaling information related to ISP, an operation of signaling information related to MRL, and an operation of signaling information related to MPM may be skipped.

For other conditions and operations, the description made with respect to the fourth configuration of the intra prediction mode information signaling unit 9320 and the sixth configuration of the intra prediction mode information signaling unit 9320 may also be applied to the ninth configuration of the intra prediction mode information signaling unit 9320.

Fig. 104 shows a tenth configuration of an intra prediction mode information signaling unit according to an embodiment.

A tenth configuration of the intra prediction mode information signaling unit 9320 may indicate a configuration of the intra prediction mode information signaling unit 9320 for performing another method for signaling a plurality of pieces of information related to an intra prediction method when it is determined whether an operation of signaling MIP-related information will be performed based on a priority signaled non-plane flag and a plane mode is not available in an ISP as described above with reference to fig. 55.

According to the tenth configuration of the intra prediction mode information signaling unit 9320, the MIP-related information and the MRL-related information may be signaled according to the value of the non-plane flag. When the value of the non-plane flag is 0, all of the operation of signaling information related to MIP, the operation of signaling information related to MRL, the operation of signaling information related to ISP, and the operation of signaling information related to MPM may be skipped. When the value of the non-plane flag is 1, all of an operation of signaling information related to MIP, an operation of signaling information related to MRL, an operation of signaling information related to ISP, and an operation of signaling information related to MPM may be performed.

For other conditions and operations, the description regarding the fourth configuration of the intra prediction mode information signaling unit 9320 and the seventh configuration of the intra prediction mode information signaling unit 9320 may also be applied to the tenth configuration of the intra prediction mode information signaling unit 9320.

Fig. 105 illustrates an eleventh configuration of an intra prediction mode information signaling unit according to an embodiment.

An eleventh configuration of the intra prediction mode information signaling unit 9320 may indicate a configuration of the intra prediction mode information signaling unit 9320 for performing the method for signaling the pieces of information related to the intra prediction method when it is determined whether the operation of signaling the information related to the MIP is to be performed based on the MPM flag signaled preferentially and the plane mode is not available in the ISP as described above with reference to fig. 56.

According to the eleventh configuration of the intra prediction mode information signaling unit 9320, the operation of signaling the MPM flag may be preferentially performed. One of the MIP flag and the non-planar flag may be signaled according to a value of the MPM flag. When the value of the MPM flag is 0, an operation of signaling information related to MIP may be performed, and all of an operation of signaling a non-planar flag, an operation of signaling information related to ISP, an operation of signaling information related to MRL, and an operation of signaling information related to MPM may be skipped.

For other conditions and operations, the description regarding the fourth configuration of the intra prediction mode information signaling unit 9320 and the eighth configuration of the intra prediction mode information signaling unit 9320 may also be applied to the eleventh configuration of the intra prediction mode information signaling unit 9320.

The foregoing configuration of the intra prediction mode information signaling unit 9320 is only an example, and thus, according to an embodiment, the configuration of the sub components may be changed and the order of operation of the sub components may be changed. Further, a specific sub-component may be added to the aforementioned configuration, and the intra prediction mode information signaling unit 9320 may be configured using some of the sub-components described in the configuration.

Fig. 106 is a flowchart illustrating a target block prediction method and a bitstream generation method according to an embodiment.

The target block prediction method and the bitstream generation method according to the embodiment may be performed by the encoding apparatus 1600. The embodiments may be part of a target block encoding method or a video encoding method.

In step 10610, the processing unit 1610 may determine a prediction mode to be applied to the encoding of the target block.

The processing unit 1610 may determine the prediction information based on the method used in the above-described embodiment.

For example, the prediction information may include information indicating an intra prediction mode for the target block and information indicating a direction of intra prediction. The prediction information may include a plurality of pieces of information signaled with respect to the above-described intra prediction. For example, the prediction information may be an ISP flag, an ISP mode, the number of ISPs, an MRL flag, an MRL index, an MIP flag, an MIP mode, an MPM flag, an MPM index, a non-flat flag, and the like. Further, the prediction information may include additional information for intra prediction described in the embodiments, in addition to the above information.

The prediction information may include a plurality of pieces of information.

The plurality of prediction information may include one or more of an ISP flag, an ISP mode, a number of ISPs, an MRL flag, an MRL index, an MIP flag, an MIP mode, an MPM flag, an MPM index, and a non-planar flag.

In step 10620, the processing unit 1610 may perform prediction for the target block using the determined prediction information.

Here, the prediction may be intra prediction, and may include intra prediction using sub-partitions. When sub-partitions are used, the target to be encoded (such as prediction) may be a sub-block. Thus, the description of the target block in the embodiments may also be applied to the sub-blocks.

Information about the encoded target block may be generated by performing prediction with respect to the target block. The information on the encoded target block may include information for specifying an intra prediction mode and an intra prediction direction for the target block, and may include information on the encoded sub block.

The prediction block may be generated via prediction with respect to the target block, and a residual block, which is a difference between the target block and the prediction block, may be generated. Information on the encoded target block may be generated by applying transformation and quantization to the residual block.

The information on the encoded target block may include transformed and quantized coefficients for the target block. Further, the information on the encoded target block may include encoding parameters for the target block.

In step 10630, the processing unit 1610 may generate a bitstream.

The bitstream may include information on the encoded target block.

The information on the encoded target block may include a plurality of pieces of prediction information required for prediction of the target block.

Here, the pieces of prediction information may be included in the bitstream in the order of signaling described in the above embodiments. In an embodiment, the description indicating that the operation of signaling the specific prediction information is performed may indicate that the prediction information is included in the bitstream. Further, in an embodiment, skipping the operation of signaling the specific prediction information may indicate that the specific prediction information is not included in the bitstream.

The bitstream may comprise encoding parameters related to the target block and/or properties of the target block.

Whether or not particular prediction information is to be used may be determined based on a calculation formula using one or more encoding parameters. For example, when a result of a first calculation formula using one or more encoding parameters satisfies a certain condition, the bitstream may include the certain prediction information. In other words, the specific prediction information may be signaled when a result of the first calculation formula using one or more encoding parameters satisfies a specific condition. The specific prediction information may be omitted from the bitstream when a result of the first calculation formula using the one or more encoding parameters does not satisfy the specific condition. Here, the encoding apparatus 1600 and the decoding apparatus 1700 may derive the specific prediction information that is not signaled by the bitstream, using the second calculation formula using one or more encoding parameters in the same manner. In other words, the first calculation formula may represent a condition indicating: the specific prediction information is either 1) explicitly signaled by the bitstream or 2) derived using a second calculation formula.

The information included in the bitstream may be generated in step 10630, or may be generated at least in part in step 10610 and step 10620. Optionally, step 10610, step 10620, and step 10630 may be performed repeatedly or simultaneously.

The processing unit 1610 may store the generated bit stream in the memory 1640. Alternatively, the communication unit 1620 may transmit the bit stream to the decoding apparatus 1700.

The information in the bitstream may be information entropy-encoded by the processing unit 1610.

The target block prediction method using a bitstream according to an embodiment may be performed by the decoding apparatus 1700. The embodiments may be part of a target block decoding method or a video decoding method.

In step 10710, the communication unit 1320 may acquire a bitstream. The communication unit 1720 may receive a bitstream from the encoding apparatus 1600.

The bitstream may include information on the encoded target block.

The information about the encoded target block may include transformed and quantized coefficients for the target block. The information on the encoded target block may include encoding parameters for the target block.

The information on the encoded target block may include prediction information required for prediction of the target block. The prediction information may include a plurality of pieces of information.

Here, the pieces of prediction information may be extracted from the bitstream in the order of signaling described in the above embodiments. In an embodiment, the description indicating to perform the operation of signaling the specific prediction information may represent extracting the prediction information from the bitstream. Further, in an embodiment, skipping the operation of signaling the specific prediction information may mean not extracting the specific prediction information from the bitstream.

Whether or not the specific prediction information will be used may be determined based on a first calculation formula using one or more encoding parameters. For example, when a result of a first calculation formula using one or more encoding parameters satisfies a certain condition, the bitstream may include the certain prediction information. In other words, the specific prediction information may be signaled when a result of the first calculation formula using one or more encoding parameters satisfies a specific condition. The specific prediction information may be omitted from the bitstream when a result of the first calculation formula using the one or more encoding parameters does not satisfy the specific condition. Further, when the result of the first calculation formula using one or more encoding parameters does not satisfy the specific condition, the specific prediction information may not be extracted from the bitstream. Here, the encoding apparatus 1600 and the decoding apparatus 1700 may derive the specific prediction information that is not signaled by the bitstream, using the second calculation formula using one or more encoding parameters in the same manner. In other words, the first calculation formula may represent a condition indicating: the specific prediction information is either 1) explicitly signaled by the bitstream or 2) derived using a second calculation formula.

Entropy encoded information in the bitstream may be entropy decoded by the processing unit 1610.

The processing unit 1710 may store the acquired bitstream in the memory 1740.

In step 10720, the processing unit 1710 may determine the prediction mode to be applied to the decoding of the target block.

The processing unit 1710 may determine the prediction mode based on the method used in the above-described embodiment.

At step 10730, the processing unit may perform prediction for the target block using prediction information obtained from the bitstream.

Here, the prediction may be intra prediction, and may include intra prediction using sub-partitions. When sub-partitions are used, the target to be decoded (such as prediction) may be a sub-block. Thus, the description of the target block in the embodiments may also be applied to the sub-blocks.

At step 10730, a prediction block may be generated by performing prediction with respect to the target block based on the prediction information, and a reconstructed block, which is the sum of the prediction block and the reconstructed residual block, may be generated.

The above embodiments may be performed by the encoding apparatus 1600 and the decoding apparatus 1700 using methods identical to and/or corresponding to each other. Further, for encoding and/or decoding of images, combinations of one or more of the above embodiments may be used.

In the encoding apparatus 1600 and the decoding apparatus 1700, the order of applications of the embodiments may be different from each other. Alternatively, in the encoding apparatus 1600 and the decoding apparatus 1700, the order of applications of the embodiments may be (at least partially) the same as each other.

In the encoding apparatus 1600 and the decoding apparatus 1700, the order of the applications of the embodiments may be different from each other, or in the encoding apparatus 1600 and the decoding apparatus 1700, the order of the applications of the embodiments may be the same as each other.

The embodiment may be performed on each of a luminance signal and a chrominance signal. The embodiments may be equally performed on a luminance signal and a chrominance signal.

The form of the block to which embodiments of the present disclosure are applied may have a square or non-square shape.

The embodiments of the present disclosure may be applied according to the size of at least one of a target block, an encoding block, a prediction block, a transform block, a current block, an encoding unit, a prediction unit, a transform unit, a unit, and a current unit. Here, the size may be defined as a minimum size and/or a maximum size such that the embodiment is applied, and may be defined as a fixed size to which the embodiment is applied. Further, in the embodiments, the first embodiment may be applied to the first size, and the second embodiment may be applied to the second size. That is, the embodiments can be comprehensively applied according to the size. Further, the embodiments of the present disclosure may be applied only to the case where the size is equal to or greater than the minimum size and less than or equal to the maximum size. That is, the embodiments may be applied only to the case where the block size falls within a specific range.

Further, the embodiments of the present disclosure may be applied only to the case where the condition that the size is equal to or greater than the minimum size and the condition that the size is less than or equal to the maximum size are satisfied, wherein each of the minimum size and the maximum size may be the size of one of the blocks described in the above embodiments and the units described in the above embodiments. That is, a block that is a target of the minimum size may be different from a block that is a target of the maximum size. For example, embodiments of the present disclosure may be applied only to the case where the size of the target block is equal to or greater than the minimum size of the block and less than or equal to the maximum size of the block.

For example, the embodiment may be applied only to the case where the size of the target block is equal to or greater than 8 × 8. For example, the embodiment can be applied only to the case where the size of the target block is equal to or larger than 16 × 16. For example, the embodiment can be applied only to the case where the size of the target block is equal to or larger than 32 × 32. For example, the embodiment can be applied only to the case where the size of the target block is equal to or larger than 64 × 64. For example, the embodiment may be applied only to the case where the size of the target block is equal to or greater than 128 × 128. For example, the embodiment can be applied only to the case where the size of the target block is 4 × 4. For example, the embodiments may be applied only to the case where the size of the target block is less than or equal to 8 × 8. For example, the embodiments may be applied only to the case where the size of the target block is less than or equal to 16 × 16. For example, the embodiment can be applied only to the case where the size of the target block is equal to or larger than 8 × 8 and smaller than or equal to 16 × 16. For example, the embodiment can be applied only to the case where the size of the target block is equal to or larger than 16 × 16 and smaller than or equal to 64 × 64.

Embodiments of the present disclosure may be applied according to temporal layers. To identify the temporal layer to which an embodiment is applicable, a separate identifier may be signaled, and an embodiment may be applied to a temporal layer specified by the corresponding identifier. Here, the identifier may be defined as the lowest (bottom) layer and/or the highest (top) layer to which the embodiment is applicable, and may be defined to indicate a specific layer to which the embodiment is applied. In addition, fixed time layers for application embodiments may also be defined.

For example, the embodiment may be applied only to a case where the temporal layer of the target image is the lowermost layer. For example, the embodiments may be applied only to the case where the temporal layer identifier of the target image is equal to or greater than 1. For example, the embodiment may be applied only to a case where the temporal layer of the target image is the highest layer.

A stripe type or a parallel block group type of an embodiment of the present invention to which the embodiment is applied may be defined, and the embodiment of the present invention may be applied according to the corresponding stripe type or parallel block group type.

In the above-described embodiments, it can be explained that, during application of a specific process to a specific target, assuming that a specific condition may be required and the specific process is performed under a specific determination, when it has been described that whether the specific condition is satisfied is determined based on a specific encoding parameter or the specific determination is made based on the specific encoding parameter, the specific encoding parameter may be replaced with an additional encoding parameter. In other words, encoding parameters that affect a particular condition or a particular determination may be considered merely exemplary, and it is understood that a combination of one or more additional encoding parameters, in addition to a particular encoding parameter, is used as a particular encoding parameter.

In the above-described embodiments, although the method has been described based on the flowchart as a series of steps or units, the present disclosure is not limited to the order of the steps, and some steps may be performed in an order different from that of the described steps or simultaneously with other steps. Furthermore, those skilled in the art will understand that: the steps shown in the flowcharts are not exclusive and may include other steps as well, or one or more steps in the flowcharts may be deleted without departing from the scope of the present disclosure.

The above-described embodiments include examples of various aspects. Although not all possible combinations for indicating the various aspects may be described, a person skilled in the art will appreciate that other combinations are possible than those explicitly described. Accordingly, it is to be understood that the present disclosure includes other substitutions, alterations, and modifications as fall within the scope of the appended claims.

The above-described embodiments according to the present disclosure may be implemented as a program that can be executed by various computer apparatuses, and may be recorded on a computer-readable storage medium. Computer readable storage media may include program instructions, data files, and data structures, alone or in combination. The program instructions recorded on the storage medium may be specially designed and configured for the present disclosure, or may be known or available to those having ordinary skill in the computer software art.

Computer-readable storage media may include information used in embodiments of the present disclosure. For example, a computer-readable storage medium may include a bitstream, and the bitstream may include information described above in embodiments of the present disclosure.

The computer-readable storage medium may include a non-transitory computer-readable medium.

Examples of the computer-readable storage medium may include all types of hardware devices specifically configured to record and execute program instructions, such as magnetic media (such as hard disks, floppy disks, and magnetic tapes), optical media (such as Compact Disk (CD) -ROMs and Digital Versatile Disks (DVDs)), magneto-optical media (such as floppy disks, ROMs, RAMs, and flash memories). Examples of program instructions include both machine code, such as created by a compiler, and high-level language code that may be executed by the computer using an interpreter. The hardware devices may be configured to operate as one or more software modules to perform the operations of the present disclosure, and vice versa.

As described above, although the present disclosure has been described based on specific details (such as detailed components and a limited number of embodiments and drawings), which are provided only for easy understanding of the entire disclosure, the present disclosure is not limited to these embodiments, and those skilled in the art will practice various changes and modifications according to the above description.

Therefore, it is to be understood that the spirit of the present embodiments is not limited to the above-described embodiments, and the appended claims and their equivalents and modifications fall within the scope of the present disclosure.

Claims

1. A method of decoding, comprising:

determining a prediction mode for a target block; and is

Performing prediction for the target block using the determined prediction mode.