KR20200088295A - Video decoding method and device by local luminance compensation, Video encoding method and device by local luminance compensation - Google Patents

Abstract

During a video encoding and decoding process, an available block among neighboring blocks neighboring the current block in the same frame as the current block is determined, local luminance compensation information is derived from the available block, and the local luminance compensation information is A method and apparatus for determining a local luminance compensation model based on the local luminance compensation model and applying the local luminance compensation model to the current block are proposed.

Description

Video decoding method and device by local luminance compensation, Video encoding method and device by local luminance compensation

The present disclosure relates to a video decoding method and a video decoding apparatus, and proposes a method and apparatus for local luminance compensation.

The image data is encoded by a codec according to a predetermined data compression standard, for example, a Moving Picture Expert Group (MPEG) standard, and then stored in a recording medium in the form of a bitstream or transmitted through a communication channel.

With the development and dissemination of hardware capable of playing and storing high-resolution or high-definition video content, the need for a codec that effectively encodes or decodes high-resolution or high-definition video content is increasing. The encoded image content can be reproduced by decoding. Recently, methods for effectively compressing high-resolution or high-definition video content have been implemented. For example, it has been proposed that an image compression technique may be effectively implemented by dividing an image to be encoded by an arbitrary method or manipulating data.

As one of the techniques for manipulating data, when the luminance between layers in the interlayer encoding and decoding method is inconsistent, movement is performed to obtain effective performance against luminance change using reconstructed pixels of a reference frame and reconstructed samples of a current frame. It is common to perform luminance compensation by performing compensation once more.

In the process of video encoding and decoding, in applying local luminance compensation to compensate for a luminance difference to prediction pixels of a current block by properly reflecting a change in luminance of an image, stored from available blocks among neighboring blocks neighboring the current block We propose a method and apparatus for deriving local luminance compensation information and performing local luminance compensation.

In order to solve the above technical problem, the video decoding method proposed in the present disclosure includes: determining an available block among neighboring blocks neighboring the current block in the same frame as the current block; Deriving local luminance compensation information from the available blocks; Determining a local luminance compensation model based on the local luminance compensation information; And applying local luminance compensation using the determined local luminance compensation model to the current block.

In order to solve the above technical problem, the video decoding apparatus proposed in the present disclosure includes a memory; And at least one processor connected to the memory, the at least one processor: determining an available block among neighboring blocks adjacent to the current block in the same frame as the current block, and local from the available block. It may be configured to derive luminance compensation information, determine a local luminance compensation model based on the local luminance compensation information, and apply local luminance compensation using the determined local luminance compensation model to the current block.

In order to solve the above technical problem, the video encoding method proposed in the present disclosure includes: determining an available block among neighboring blocks neighboring the current block in the same frame as the current block; Deriving local luminance compensation information from the available blocks; Determining a local luminance compensation model based on the local luminance compensation information; And applying local luminance compensation using the determined local luminance compensation model to the current block.

In order to solve the above technical problem, the video encoding apparatus proposed in the present disclosure includes at least one processor connected to the memory, and the at least one processor includes: a neighbor adjacent to the current block in the same frame as the current block. Determine an available block among blocks, derive local luminance compensation information from the available block, determine a local luminance compensation model based on the local luminance compensation information, and determine the local luminance compensation model determined for the current block. It may be configured to apply local luminance compensation.

In the process of video encoding and decoding, local block compensation is applied to determine an available block among neighboring blocks adjacent to the current block, and the stored local brightness compensation information of the determined available block is derived to obtain the local brightness according to the local brightness compensation model. By applying compensation, it is possible to remove access to the reconstructed pixels of the neighboring block and the reconstructed pixels of the reference frame adjacent to the current block of the current frame. In addition, in reflecting the local luminance change, by using the sum of the DC residual values and the predicted samples obtained from motion compensation of the current frame or the predicted samples of the current frame, the inverse of neighboring blocks neighboring the current block of the current frame Since the quantization and inverse transform is completed, there is no need to wait until the reconstructed pixels of the neighboring block are available, thereby reducing the latency caused by access to the reconstructed pixels of the neighboring block.

1 is a schematic block diagram of an image decoding apparatus 100 according to an embodiment.
2 is a flowchart of an image decoding method according to an embodiment.
FIG. 3 illustrates a process in which an image decoding apparatus determines at least one coding unit by dividing a current coding unit according to an embodiment.
4 is a diagram for a process in which an image decoding apparatus determines at least one coding unit by dividing a coding unit having a non-square shape according to an embodiment.
5 illustrates a process in which an image decoding apparatus divides a coding unit based on at least one of block shape information and split shape mode information according to an embodiment.
6 illustrates a method for an image decoding apparatus to determine a predetermined coding unit among odd coding units according to an embodiment.
7 illustrates an order in which a plurality of coding units are processed when a video decoding apparatus determines a plurality of coding units by dividing a current coding unit according to an embodiment.
FIG. 8 is a diagram illustrating a process in which the video decoding apparatus determines that the current coding unit is divided into an odd number of coding units when the coding unit cannot be processed in a predetermined order according to an embodiment.
9 is a diagram illustrating a process in which an image decoding apparatus determines at least one coding unit by dividing a first coding unit according to an embodiment.
FIG. 10 is a diagram illustrating a method in which a second coding unit may be split when a second coding unit having a non-square shape determined by dividing a first coding unit satisfies a predetermined condition according to an embodiment. Shows that.
11 is a diagram illustrating a process in which an image decoding apparatus divides a coding unit in a square shape when the split mode mode information cannot be divided into 4 square coding units according to an embodiment.
12 illustrates that a processing order among a plurality of coding units may vary according to a splitting process of coding units according to an embodiment.
13 is a diagram illustrating a process in which a depth of a coding unit is determined as a shape and a size of a coding unit change when a coding unit is recursively divided and a plurality of coding units are determined according to an embodiment.
14 is a diagram for a depth and a coding index (part index, PID) that can be determined according to the type and size of coding units, according to an embodiment.
15 illustrates that a plurality of coding units are determined according to a plurality of predetermined data units included in a picture according to an embodiment.
16 illustrates a processing block serving as a criterion for determining a determination order of a reference coding unit included in a picture according to an embodiment.
17 is a block diagram of a video decoding apparatus 1700 according to an embodiment.
18 is a flowchart of a video decoding method according to an embodiment.
19 is a block diagram of a video encoding apparatus 1900 according to an embodiment.
20 is a flowchart of a video encoding method according to an embodiment.
21A and 21B show an example of a modeling process for applying local luminance compensation using prediction pixels and reconstructed pixels of a current frame.
22 illustrates local luminance compensation parameters according to an embodiment.
23 shows an example of positions of samples used in the calculation of the local luminance compensation parameter of the current block of the current frame.
24 illustrates a location of samples used for calculation of a current block, a neighboring block adjacent to the current block, and local luminance compensation parameters of the neighboring block according to an embodiment.
25 illustrates local luminance compensation parameters according to another embodiment.
26 shows another example of a local luminance compensation model using predictive and reconstructed pixels of the current frame.
27 shows another example of a modeling process for applying local luminance compensation.
28 shows another example of a local luminance compensation model using the sum of the pixel to be reconstructed of the reference frame and the predicted pixel value and DC residual value of the current frame.

Best mode for carrying out the invention

A video decoding method according to an embodiment proposed in the present disclosure may include determining an available block among neighboring blocks neighboring the current block in the same frame as the current block; Deriving local luminance compensation information from the available blocks; Determining a local luminance compensation model based on the local luminance compensation information; And applying local luminance compensation using the determined local luminance compensation model to the current block.

According to an embodiment, the neighboring blocks may be adjacent to at least one of left, upper left, upper, right, and right sides of the current block.

According to an embodiment, the local luminance compensation information may include local luminance compensation parameters corresponding to regions located at the left, lower, and right edges of the neighboring blocks.

According to an embodiment, the local luminance compensation parameters may be determined and stored based on a predicted sample and a reconstructed sample of regions located at left, bottom, and right edges of the peripheral block.

According to an embodiment, the local luminance compensation information includes local luminance compensation parameters determined using a prediction sample of the neighboring block and a reconstructed sample of the neighboring block, and the prediction sample includes motion compensation for the neighboring block. It may be a stored sample after being performed.

According to an embodiment, local luminance compensation parameters are predicted sample values of regions located at each of the left, bottom, and right edges of the neighboring block and regions located at each edge of the left, bottom, and right of the neighboring blocks. It can be determined and stored based on the sum of the predicted sample value of the DC residual value.

According to an embodiment, the local luminance compensation parameters may be determined and stored based on a sum of a predicted sample value of the neighboring block and a predicted sample value of the neighboring block and a DC residual value.

According to an embodiment, the local luminance compensation information is determined by using a reconstructed sample of a neighboring reference block indicated by a sum of a prediction sample value and a DC residual value of the neighboring block and motion information of the neighboring block. It includes parameters, and the predicted sample value may be a value stored after motion compensation for the neighboring block is performed.

According to an embodiment, the available blocks may be determined in a predetermined order based on the size or shape of the current block.

According to an embodiment, if the neighboring block uses a reference list of an index different from the current block or is intra predicted, it may not be determined as the available block.

According to an embodiment, when the current block is a merge mode or a skip mode, local luminance compensation information may be derived from a block neighboring a block corresponding to the current block according to the merge mode or skip mode.

According to an embodiment, when the available block does not exist among the neighboring blocks, local luminance compensation may not be applied.

According to an embodiment, when the available block does not exist among the neighboring blocks, the local luminance compensation information includes a default local luminance compensation parameter, and local luminance in the current block using the default luminance compensation parameter. Rewards can be applied.

According to an embodiment, the local luminance compensation parameters may be classified according to the bidirectional reference list number of the peripheral block and three color components.

A video encoding method according to an embodiment proposed in the present disclosure may include determining an available block among neighboring blocks neighboring the current block in the same frame as the current block; Deriving local luminance compensation information from the available blocks; Determining a local luminance compensation model based on the local luminance compensation information; And applying local luminance compensation using the determined local luminance compensation model to the current block.

A video decoding apparatus according to an embodiment proposed in the present disclosure includes a memory; And at least one processor connected to the memory, the at least one processor: determining an available block among neighboring blocks adjacent to the current block in the same frame as the current block, and local from the available block. It may be configured to derive luminance compensation information, determine a local luminance compensation model based on the local luminance compensation information, and apply local luminance compensation using the determined local luminance compensation model to the current block.

Mode for carrying out the invention

Advantages and features of the disclosed embodiments, and methods of achieving them will become apparent with reference to the embodiments described below along with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, and may be implemented in various different forms, and only the present embodiments allow the present disclosure to be complete, and those skilled in the art to which the present disclosure pertains. It is only provided to completely inform the person of the scope of the invention.

The terms used in the present specification will be briefly described, and the disclosed embodiments will be described in detail.

The terms used in the present specification have selected general terms that are currently widely used as possible while considering functions in the present disclosure, but this may be changed according to intentions or precedents of technicians engaged in related fields, appearance of new technologies, and the like. In addition, in certain cases, some terms are arbitrarily selected by the applicant, and in this case, their meanings will be described in detail in the description of the applicable invention. Therefore, the terms used in the present disclosure should be defined based on the meaning of the terms and the contents of the present disclosure, not simply the names of the terms.

In the present specification, a singular expression includes a plural expression unless the context clearly indicates that it is singular.

When a certain part of the specification "includes" a certain component, this means that other components may be further included instead of excluding other components unless otherwise specified.

Also, the term "part" used in the specification means a software or hardware component, and "part" performs certain roles. However, "part" is not meant to be limited to software or hardware. The "unit" may be configured to be in an addressable storage medium or may be configured to reproduce one or more processors. Thus, as an example, "part" refers to components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, Includes subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, database, data structures, tables, arrays and variables. The functionality provided within components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts".

According to an embodiment of the present disclosure, the “unit” may be implemented as a processor and memory. The term "processor" should be broadly interpreted to include general purpose processors, central processing units (CPUs), microprocessors, digital signal processors (DSPs), controllers, microcontrollers, state machines, and the like. In some environments, “processor” may refer to an application specific semiconductor (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), and the like. The term "processor" refers to a combination of processing devices, such as, for example, a combination of a DSP and a microprocessor, a combination of a plurality of microprocessors, a combination of one or more microprocessors in combination with a DSP core, or any other combination of such configurations. It can also be referred to.

The term "memory" should be interpreted broadly to include any electronic component capable of storing electronic information. The term memory is random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), erase-programmable read-only memory (EPROM), electrical May refer to various types of processor-readable media such as erasable PROM (EEPROM), flash memory, magnetic or optical data storage, registers, and the like. A memory is said to be in electronic communication with the processor if the processor can read information from and/or write information to the memory. The memory integrated in the processor is in electronic communication with the processor.

Hereinafter, the "image" may represent a static image such as a still image of a video or a dynamic image such as a video, that is, the video itself.

Hereinafter, "sample" means data to be processed as data allocated to a sampling position of an image. For example, pixel values in a spatial domain image and transform coefficients on a transform region may be samples. A unit including at least one sample may be defined as a block.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present disclosure pertains can easily implement the embodiments. In addition, in order to clearly describe the present disclosure in the drawings, parts irrelevant to the description are omitted.

Hereinafter, an image encoding apparatus and an image decoding apparatus, an image encoding method, and an image decoding method will be described in detail with reference to FIGS. 1 to 16. A method of determining a data unit of an image according to an embodiment is described with reference to FIGS. 3 to 16, and among neighboring blocks neighboring a current block of the present invention according to an embodiment with reference to FIGS. 17 to 28 A method of determining an available block and deriving local luminance compensation information from the available block to determine a local luminance compensation model based on the local luminance compensation information and applying local luminance compensation according to the determined local luminance compensation model will be described below.

Hereinafter, a method and apparatus for adaptively selecting a context model based on various types of coding units according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2.

1 is a schematic block diagram of an image decoding apparatus 100 according to an embodiment.

The image decoding apparatus 100 may include a receiving unit 110 and a decoding unit 120. The receiving unit 110 and the decoding unit 120 may include at least one processor. Also, the receiving unit 110 and the decoding unit 120 may include a memory that stores instructions to be executed by at least one processor.

The receiver 110 may receive a bitstream. The bitstream includes information encoded by the video encoding apparatus 2200 described later. Also, the bitstream may be transmitted from the video encoding apparatus 2200. The video encoding apparatus 2200 and the video decoding apparatus 100 may be connected by wire or wireless, and the reception unit 110 may receive a bitstream through wire or wireless. The receiving unit 110 may receive a bitstream from a storage medium such as an optical media, hard disk, or the like. The decoder 120 may reconstruct an image based on information obtained from the received bitstream. The decoder 120 may obtain a syntax element for reconstructing an image from a bitstream. The decoder 120 may reconstruct an image based on the syntax element.

The operation of the video decoding apparatus 100 will be described in more detail with reference to FIG. 2.

2 is a flowchart of an image decoding method according to an embodiment.

According to an embodiment of the present disclosure, the receiver 110 receives a bitstream.

The video decoding apparatus 100 performs step 210 of acquiring an empty string corresponding to a split mode mode of a coding unit from a bitstream. The image decoding apparatus 100 performs step 220 of determining a division rule of a coding unit. Also, the image decoding apparatus 100 performs a step 230 of dividing the coding unit into a plurality of coding units based on at least one of the binstring corresponding to the split mode mode and the splitting rule. In order to determine a division rule, the image decoding apparatus 100 may determine an allowable first range of the size of the coding unit according to a ratio of width and height of the coding unit. In order to determine a division rule, the image decoding apparatus 100 may determine an allowable second range of a size of a coding unit according to a split mode mode of a coding unit.

Hereinafter, division of a coding unit according to an embodiment of the present disclosure will be described in detail.

First, one picture may be divided into one or more slices. One slice may be a sequence of one or more largest coding unit (CTU). In contrast to the maximum coding unit (CTU), there is a maximum coding block (CTB).

The largest coding block (CTB) means an NxN block including NxN samples (N is an integer). Each color component may be divided into one or more largest coding blocks.

When a picture has three sample arrays (sample arrays for each of Y, Cr, and Cb components), the largest coding unit (CTU) is the largest coding block of a luma sample and two largest coding blocks of chroma samples corresponding thereto, and luma A unit including syntax structures used to encode samples and chroma samples. When a picture is a monochrome picture, a maximum coding unit is a unit including a maximum coding block of a monochrome sample and syntax structures used to encode monochrome samples. When a picture is a picture that is coded by a color plane separated for each color component, a maximum coding unit is a unit including syntax structures used to code a corresponding picture and samples of a picture.

One maximum coding block (CTB) may be divided into an MxN coding block including MxN samples (M and N are integers).

When a picture has a sample array for each of Y, Cr, and Cb components, a coding unit (CU) is a coding block of a luma sample and two coding blocks of chroma samples corresponding thereto, and luma samples and chroma samples. It is a unit that contains syntax structures used to do this. When a picture is a monochrome picture, a coding unit is a unit including a coding block of a monochrome sample and syntax structures used to encode monochrome samples. When a picture is a picture encoded by a color plane separated for each color component, a coding unit is a unit including syntax structures used for encoding a picture and samples of a picture.

As described above, the maximum coding block and the maximum coding unit are concepts that are distinguished from each other, and the coding block and the coding unit are concepts that are different from each other. That is, the (maximum) coding unit means a (maximum) coding block including a corresponding sample and a data structure including a syntax structure corresponding thereto. However, since a person skilled in the art can understand that the (maximum) coding unit or the (maximum) coding block refers to a block of a predetermined size including a predetermined number of samples, in the following specification, the maximum coding block and the maximum coding unit, or the coding block and the coding unit Refers to without distinction unless otherwise specified.

The image may be divided into a maximum coding unit (CTU). The size of the largest coding unit may be determined based on information obtained from a bitstream. The shape of the largest coding unit may have a square of the same size. However, it is not limited thereto.

For example, information on the maximum size of a luma coding block may be obtained from a bitstream. For example, the maximum size of the luma coding block indicated by the information on the maximum size of the luma coding block may be one of 4x4, 8x8, 16x16, 32x32, 64x64, 128x128, and 256x256.

For example, information on a difference between a maximum size of a luma coding block that can be divided into two and a luma block size may be obtained from a bitstream. Information about the difference in luma block sizes may indicate a size difference between a luma maximum coding unit and a maximum luma coding block capable of being divided into two. Accordingly, when information about the maximum size of a dividable luma coding block obtained from a bitstream and information about a difference in a luma block size are combined, the size of the luma maximum coding unit may be determined. If the size of the luma maximum coding unit is used, the size of the chroma maximum coding unit may also be determined. For example, if the ratio of Y: Cb: Cr is 4:2:0 according to the color format, the size of the chroma block may be half the size of the luma block, and the size of the chroma maximum coding unit may be equal to that of the luma maximum coding unit. It can be half the size.

According to an embodiment, since information on the maximum size of a luma coding block capable of binary splitting is obtained from a bitstream, a maximum size of a luma coding block capable of binary splitting may be variably determined. Alternatively, the maximum size of a luma coding block capable of ternary split may be fixed. For example, a maximum size of a luma coding block capable of ternary division in an I slice may be 32x32, and a maximum size of a luma coding block capable of ternary division in a P slice or a B slice may be 64x64.

Also, the largest coding unit may be hierarchically divided into coding units based on split mode mode information obtained from a bitstream. As the split mode mode information, at least one of information indicating whether to split a quad, information indicating whether to split, or not, split direction information, and split type information may be obtained from a bitstream.

For example, information indicating whether to split a quad may indicate whether the current coding unit is to be quad split (QUAD_SPLIT) or not to be split.

If the current coding unit is quadranted or not, information indicating whether to split the current coding unit may indicate whether the current coding unit is no longer split (NO_SPLIT) or binary/ternary split.

When the current coding unit is binary or ternary split, the split direction information indicates that the current coding unit is split in either the horizontal direction or the vertical direction.

If the current coding unit is split in the horizontal or vertical direction, the split type information indicates that the current coding unit is split into binary split (or ternary split).

According to the split direction information and split type information, a split mode of a current coding unit may be determined. The split mode when the current coding unit is binary split in the horizontal direction is binary horizontal split (SPLIT_BT_HOR), ternary horizontal split in the horizontal direction split (SPLIT_TT_HOR), and split mode when the binary split in the vertical direction is The binary vertical split (SPLIT_BT_VER) and the split mode in the case of ternary split in the vertical direction may be determined as ternary vertical split (SPLIT_BT_VER).

The video decoding apparatus 100 may obtain split mode mode information from a bitstream from one empty string. The form of the bitstream received by the image decoding apparatus 100 may include a fixed length binary code, an unary code, a truncated unary code, a predetermined binary code, and the like. The binstring is a binary representation of information. The binstring may consist of at least one bit. The video decoding apparatus 100 may obtain segmentation mode mode information corresponding to the empty string based on the segmentation rule. The video decoding apparatus 100 may determine whether to divide the coding unit into quads, or not, or a split direction and a split type, based on one empty string.

The coding unit may be smaller than or equal to the maximum coding unit. For example, since the largest coding unit is a coding unit having a maximum size, it is one of coding units. When the split mode mode information for the largest coding unit is not split, the coding unit determined in the largest coding unit has the same size as the largest coding unit. When the split mode mode information for the largest coding unit is split, the largest coding unit may be divided into coding units. Also, when split mode mode information for a coding unit indicates split, coding units may be split into smaller coding units. However, the segmentation of the image is not limited thereto, and the maximum coding unit and the coding unit may not be distinguished. The division of the coding unit will be described in more detail in FIGS. 3 to 16.

Also, one or more prediction blocks for prediction may be determined from coding units. The prediction block may be equal to or smaller than the coding unit. Also, one or more transform blocks for transformation may be determined from coding units. The transform block may be equal to or smaller than the coding unit.

The shape and size of the transform block and the prediction block may not be related to each other.

In another embodiment, prediction may be performed using a coding unit as a coding block as a prediction block. Also, a coding unit may be transformed using a coding unit as a transform block.

The division of the coding unit will be described in more detail in FIGS. 3 to 16. The current block and neighboring blocks of the present disclosure may represent one of the largest coding unit, coding unit, prediction block, and transform block. Also, the current block or the current coding unit is a block in which decoding or encoding is currently in progress or a block in which the current division is in progress. The neighboring block may be a block reconstructed before the current block. The neighboring blocks can be spatially or temporally adjacent from the current block. The neighboring block may be located in one of the lower left, left, upper left, upper, upper right, right, and lower sides of the current block.

3 illustrates a process in which the video decoding apparatus 100 determines at least one coding unit by dividing a current coding unit according to an embodiment.

The block form may include 4Nx4N, 4Nx2N, 2Nx4N, 4NxN, Nx4N, 32NxN, Nx32N, 16NxN, Nx16N, 8NxN or Nx8N. Here, N may be a positive integer. The block type information is information indicating at least one of a shape, direction, width and height ratio or size of a coding unit.

The shape of the coding unit may include a square and a non-square. When the width and height of the coding unit are the same length (that is, when the block type of the coding unit is 4Nx4N), the image decoding apparatus 100 may determine block type information of the coding unit as a square. The image decoding apparatus 100 may determine the shape of the coding unit as a non-square.

When the width of the coding unit and the length of the height are different (ie, the block format of the coding unit is 4Nx2N, 2Nx4N, 4NxN, Nx4N, 32NxN, Nx32N, 16NxN, Nx16N, 8NxN or Nx8N), the image decoding apparatus 100 Block type information of a coding unit may be determined as a non-square. When the shape of the coding unit is a non-square, the image decoding apparatus 100 sets the ratio of width and height among block shape information of the coding unit to 1:2, 2:1, 1:4, 4:1, and 1:8. , 8:1, 1:16, 16:1, 1:32, 32:1. In addition, based on the length of the width and height of the coding unit, the image decoding apparatus 100 may determine whether the coding unit is horizontal or vertical. Also, based on at least one of a width length, a height length, or a width of the coding unit, the image decoding apparatus 100 may determine the size of the coding unit.

According to an embodiment, the image decoding apparatus 100 may determine a shape of a coding unit using block shape information, and determine what type of coding unit is split using split shape mode information. That is, a method of dividing a coding unit indicated by split mode mode information may be determined according to what block shape the block shape information used by the image decoding apparatus 100 represents.

The video decoding apparatus 100 may obtain split mode mode information from the bitstream. However, the present invention is not limited thereto, and the image decoding apparatus 100 and the image encoding apparatus 2200 may determine previously divided division mode mode information based on block shape information. The image decoding apparatus 100 may determine the split mode mode information previously promised for the largest coding unit or the smallest coding unit. For example, the image decoding apparatus 100 may determine split mode mode information as a quad split with respect to the largest coding unit. Also, the apparatus 100 for decoding an image may determine split mode mode information as “not split” for the minimum coding unit. Specifically, the image decoding apparatus 100 may determine the size of the largest coding unit to be 256x256. The image decoding apparatus 100 may determine the predetermined division mode mode information as quad division. Quad split is a split mode in which both the width and height of the coding unit are bisected. The video decoding apparatus 100 may obtain a coding unit having a size of 128x128 from a maximum coding unit having a size of 256x256 based on the split mode mode information. Also, the image decoding apparatus 100 may determine the size of the minimum coding unit to be 4x4. The image decoding apparatus 100 may obtain split mode mode information indicating “not splitting” with respect to the minimum coding unit.

According to an embodiment, the image decoding apparatus 100 may use block shape information indicating that the current coding unit is in a square shape. For example, the image decoding apparatus 100 may determine whether to divide the square coding unit according to the split mode mode information, whether to split vertically, horizontally, or split into four coding units. Referring to FIG. 3, when block shape information of the current coding unit 300 indicates a square shape, the decoder 120 has the same size as the current coding unit 300 according to split mode mode information indicating that it is not split. It is possible to determine the coding units 310b, 310c, 310d, 310e, 310f, etc. that are not split or the split coding mode 310a based on split mode mode information indicating a predetermined splitting method.

Referring to FIG. 3, the image decoding apparatus 100 divides two coding units 310b in which the current coding unit 300 is vertically split based on split mode mode information indicating that the split is vertically according to an embodiment. Can decide. The video decoding apparatus 100 may determine two coding units 310c that split the current coding unit 300 in the horizontal direction based on split mode mode information indicating that the split is in the horizontal direction. The video decoding apparatus 100 may determine four coding units 310d that split the current coding unit 300 in the vertical and horizontal directions based on the split mode mode information indicating that the split is in the vertical and horizontal directions. The image decoding apparatus 100 may divide three coding units 310e that split the current coding unit 300 into a vertical direction based on split type mode information indicating that the ternary split is vertically performed according to an embodiment. Can decide. The image decoding apparatus 100 may determine three coding units 310f that split the current coding unit 300 in the horizontal direction based on split mode mode information indicating that the ternary split is in the horizontal direction. However, the division form in which a square coding unit may be divided should not be interpreted as being limited to the above-described form, and various forms that can be represented by the division mode mode information may be included. Predetermined division types in which a square coding unit is divided will be described in detail through various embodiments below.

4 illustrates a process in which the image decoding apparatus 100 determines at least one coding unit by dividing a coding unit having a non-square shape according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may use block shape information indicating that the current coding unit is a non-square shape. The image decoding apparatus 100 may determine whether to divide the current coding unit of the non-square according to the split mode mode information or not in a predetermined method. Referring to FIG. 4, when the block form information of the current coding unit 400 or 450 represents a non-square form, the video decoding apparatus 100 according to the split form mode information indicating that the video decoding device 100 is not split ( 400 or 450), or the coding units 420a, 420b, 430a, 430b, 430c, and 470a, which are determined based on split mode mode information indicating a predetermined splitting method or determining coding units 410 or 460 having the same size. , 470b, 480a, 480b, 480c). The predetermined division method in which the non-square coding unit is divided will be described in detail through various embodiments below.

According to an embodiment, the image decoding apparatus 100 may determine a form in which a coding unit is split using split mode mode information, in which case, the split mode mode information includes at least one coding unit generated by splitting a coding unit. You can indicate the number. Referring to FIG. 4, when the split mode mode information indicates that the current coding unit 400 or 450 is split into two coding units, the image decoding apparatus 100 may use the current coding unit 400 or 450) to determine two coding units 420a, 420b, or 470a, 470b included in the current coding unit.

According to an embodiment, when the image decoding apparatus 100 divides the current coding unit 400 or 450 in a non-square shape based on the split mode mode information, the image decoding apparatus 100 displays the non-square current The current coding unit may be split by considering the position of the long side of the coding unit 400 or 450. For example, the image decoding apparatus 100 divides the current coding unit 400 or 450 in the direction of dividing the long side of the current coding unit 400 or 450 in consideration of the form of the current coding unit 400 or 450 A plurality of coding units can be determined.

According to an embodiment, when the split mode information indicates that the coding unit is split (ternary split) into odd blocks, the image decoding apparatus 100 encodes the odd number included in the current coding unit 400 or 450 Units can be determined. For example, when the split mode information indicates that the current coding unit (400 or 450) is split into three coding units, the image decoding apparatus 100 sets the current coding unit (400 or 450) into three coding units ( 430a, 430b, 430c, 480a, 480b, 480c).

According to an embodiment, the ratio of the width and height of the current coding unit 400 or 450 may be 4:1 or 1:4. When the ratio of width and height is 4:1, the length of the width is longer than the length of the height, so the block shape information may be horizontal. When the ratio of width and height is 1:4, since the length of the width is shorter than the length of the height, the block shape information may be in a vertical direction. The video decoding apparatus 100 may determine to split the current coding unit into an odd number of blocks based on the split mode mode information. Also, the apparatus 100 for decoding an image may determine a split direction of the current coding unit 400 or 450 based on block type information of the current coding unit 400 or 450. For example, when the current coding unit 400 is in the vertical direction, the image decoding apparatus 100 may determine the coding units 430a, 430b, and 430c by dividing the current coding unit 400 in the horizontal direction. In addition, when the current coding unit 450 is in the horizontal direction, the image decoding apparatus 100 may determine the coding units 480a, 480b, and 480c by dividing the current coding unit 450 in the vertical direction.

According to an embodiment, the image decoding apparatus 100 may determine an odd number of coding units included in the current coding unit 400 or 450, and not all of the determined coding units may have the same size. For example, the size of a predetermined coding unit 430b or 480b among the determined odd number of coding units 430a, 430b, 430c, 480a, 480b, and 480c is different from other coding units 430a, 430c, 480a, and 480c. You may have That is, a coding unit that can be determined by dividing the current coding unit 400 or 450 may have a plurality of types of sizes, and in some cases, an odd number of coding units 430a, 430b, 430c, 480a, 480b, and 480c. Each may have a different size.

According to an embodiment, when the split mode information indicates that the coding unit is split into odd blocks, the image decoding apparatus 100 may determine the odd number of coding units included in the current coding unit 400 or 450, Furthermore, the image decoding apparatus 100 may place a predetermined restriction on at least one coding unit among odd coding units generated by being split. Referring to FIG. 4, the image decoding apparatus 100 is a coding unit positioned in the center among three coding units 430a, 430b, 430c, 480a, 480b, and 480c generated by dividing the current coding unit 400 or 450. The decoding process for (430b, 480b) may be different from other coding units (430a, 430c, 480a, 480c). For example, the image decoding apparatus 100 restricts the coding units 430b and 480b located at the center from being split further, unlike other coding units 430a, 430c, 480a, and 480c, or only a predetermined number of times It can be restricted to split.

5 illustrates a process in which the image decoding apparatus 100 divides a coding unit based on at least one of block shape information and split shape mode information according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may determine that the first coding unit 500 in a square shape is not divided into coding units or not based on at least one of block shape information and split shape mode information. . According to an embodiment, when the split mode information indicates that the first coding unit 500 is split in the horizontal direction, the image decoding apparatus 100 splits the first coding unit 500 in the horizontal direction to perform second coding. The unit 510 can be determined. The first coding unit, the second coding unit, and the third coding unit used according to an embodiment are terms used to understand before and after splitting between coding units. For example, when the first coding unit is split, the second coding unit may be determined, and when the second coding unit is split, the third coding unit may be determined. Hereinafter, the relationship between the first coding unit, the second coding unit, and the third coding unit used may be understood as following the characteristics described above.

According to an embodiment, the image decoding apparatus 100 may determine that the determined second coding unit 510 is split into coding units based on split mode mode information or not. Referring to FIG. 5, the image decoding apparatus 100 encodes at least one third coding unit 510 of the non-square shape determined by dividing the first coding unit 500 based on the split mode mode information. The second coding unit 510 may not be divided into units 520a, 520b, 520c, and 520d. The image decoding apparatus 100 may obtain split mode mode information, and the image decoding apparatus 100 may split the first coding unit 500 based on the obtained split mode mode information to obtain a plurality of second encodings of various types. The unit (eg, 510) may be split, and the second coding unit 510 may be split according to the manner in which the first coding unit 500 is split based on the split mode mode information. According to an embodiment, when the first coding unit 500 is divided into the second coding unit 510 based on the split mode mode information for the first coding unit 500, the second coding unit 510 is also The second coding unit 510 may be split into third coding units (eg, 520a, 520b, 520c, 520d, etc.) based on the split mode mode information. That is, the coding unit may be recursively divided based on split mode mode information related to each coding unit. Accordingly, the coding unit of the square may be determined from the coding units of the non-square shape, and the coding unit of the square shape may be recursively divided to determine the coding unit of the non-square shape.

Referring to FIG. 5, a predetermined coding unit (for example, located in the center) among the odd numbered third coding units 520b, 520c, and 520d determined by dividing and determining the non-square second coding unit 510 The coding unit or the coding unit in the square form) may be recursively divided. According to an embodiment, the third coding unit 520b having a square shape, which is one of the odd numbered third coding units 520b, 520c, and 520d may be split in a horizontal direction and divided into a plurality of fourth coding units. The fourth coding unit 530b or 530d in a non-square shape, which is one of the plurality of fourth coding units 530a, 530b, 530c, and 530d, may be divided into a plurality of coding units. For example, the fourth coding unit 530b or 530d in a non-square shape may be divided into an odd number of coding units. Methods that can be used for recursive division of coding units will be described later through various embodiments.

According to an embodiment, the image decoding apparatus 100 may divide each of the third coding units 520a, 520b, 520c, and 520d into coding units based on the split mode mode information. Also, the image decoding apparatus 100 may determine not to split the second coding unit 510 based on the split mode mode information. The image decoding apparatus 100 may divide the second coding unit 510 in a non-square shape into an odd number of third coding units 520b, 520c, and 520d according to an embodiment. The video decoding apparatus 100 may place a predetermined restriction on a predetermined third coding unit among the odd number of third coding units 520b, 520c, and 520d. For example, the image decoding apparatus 100 is limited to being no longer split or to be divided into a settable number of times for the coding unit 520c located in the center among the odd number of third coding units 520b, 520c, and 520d. It can be limited to.

Referring to FIG. 5, the image decoding apparatus 100 includes a coding unit located in the center among an odd number of third coding units 520b, 520c, and 520d included in the non-square second coding unit 510. 520c) is no longer divided, or is divided into a predetermined divisional form (for example, divided into only four coding units or the second encoding unit 510 is divided into a form corresponding to the divided form), or is specified. It can be limited to dividing only by the number of times (eg dividing only n times, n>0). However, the above limitation on the coding unit 520c located in the middle is only simple embodiments and should not be interpreted as being limited to the above-described embodiments, and the coding unit 520c located in the center has different coding units 520b and 520d. ) And should be interpreted as including various restrictions that can be decoded.

According to an embodiment, the image decoding apparatus 100 may obtain split mode mode information used to split the current coding unit at a predetermined location within the current coding unit.

6 illustrates a method for the image decoding apparatus 100 to determine a predetermined coding unit among odd coding units according to an embodiment.

Referring to FIG. 6, the split mode mode information of the current coding units 600 and 650 is a sample at a predetermined position (for example, a sample located in the center) among a plurality of samples included in the current coding units 600 and 650. 640, 690)). However, a predetermined position in the current coding unit 600 in which at least one of the split mode mode information can be obtained should not be interpreted as being limited to the center position shown in FIG. 6, and a predetermined position is included in the current coding unit 600 It should be interpreted that various positions (eg, top, bottom, left, right, top left, bottom left, top right or bottom right, etc.) may be included. The image decoding apparatus 100 may obtain split mode mode information obtained from a predetermined position and determine whether to split or split the current coding unit into coding units having various shapes and sizes.

According to an embodiment, when the current coding unit is divided into a predetermined number of coding units, the image decoding apparatus 100 may select one coding unit therefrom. Methods for selecting one of a plurality of coding units may be various, and descriptions of these methods will be described later through various embodiments.

According to an embodiment, the image decoding apparatus 100 may divide the current coding unit into a plurality of coding units and determine a coding unit at a predetermined location.

According to an embodiment, the image decoding apparatus 100 may use information indicating the location of each of the odd number of coding units to determine a coding unit located in the middle of the odd number of coding units. Referring to FIG. 6, the image decoding apparatus 100 divides the current coding unit 600 or the current coding unit 650 to an odd number of coding units 620a, 620b, and 620c, or an odd number of coding units 660a, 660b, 660c). The image decoding apparatus 100 uses the information on the positions of the odd number of coding units 620a, 620b, and 620c or the odd number of coding units 660a, 660b, and 660c, and the middle coding unit 620b or the middle coding unit. (660b) can be determined. For example, the image decoding apparatus 100 determines the center of the coding units 620a, 620b, and 620c based on information indicating the location of a predetermined sample included in the coding units 620a, 620b, and 620c. The coding unit 620b located at may be determined. Specifically, the image decoding apparatus 100 may encode units 620a, 620b, and 620c based on information indicating the location of samples 630a, 630b, and 630c at the upper left of the coding units 620a, 620b, and 620c. The coding unit 620b positioned at the center may be determined by determining the position of.

According to an embodiment, information indicating the positions of the upper left samples 630a, 630b, and 630c included in the coding units 620a, 620b, and 620c is within a picture of the coding units 620a, 620b, and 620c. It may include information about the location or coordinates of. According to an embodiment, information indicating the positions of the upper left samples 630a, 630b, and 630c included in the coding units 620a, 620b, and 620c, respectively, is coding units 620a included in the current coding unit 600 , 620b, 620c), and the width or height may correspond to information indicating a difference between coordinates in a picture of coding units 620a, 620b, and 620c. That is, the image decoding apparatus 100 directly uses information about the position or coordinates in the picture of the coding units 620a, 620b, and 620c, or information about the width or height of the coding unit corresponding to a difference value between coordinates. By using, it is possible to determine the coding unit 620b located at the center.

According to an embodiment, the information indicating the position of the sample 630a at the upper left of the upper coding unit 620a may indicate (xa, ya) coordinates, and the sample 530b at the upper left of the middle coding unit 620b Information indicating the position of) may indicate (xb, yb) coordinates, and information indicating the position of the sample 630c at the upper left of the lower coding unit 620c may indicate (xc, yc) coordinates. The image decoding apparatus 100 may determine the middle coding unit 620b using coordinates of samples 630a, 630b, and 630c in the upper left included in the coding units 620a, 620b, and 620c, respectively. For example, when the coordinates of the samples 630a, 630b, and 630c in the upper left are sorted in ascending or descending order, the coding unit 620b including (xb, yb) which is the coordinates of the sample 630b located in the middle is 620b. It may be determined that the current coding unit 600 is split and the coding unit positioned in the center among the determined coding units 620a, 620b, and 620c. However, the coordinates representing the positions of the upper left samples 630a, 630b, and 630c may represent coordinates representing absolute positions in the picture, and further, the positions of the upper left samples 630a of the upper coding unit 620a may be determined. As a reference, (dxb, dyb) coordinates, which is the information indicating the relative position of the sample 630b at the upper left of the middle coding unit 620b, and the relative position of the sample 630c at the upper left of the lower coding unit 620c. Information (dxc, dyc) coordinates can also be used. In addition, a method for determining a coding unit at a predetermined location by using coordinates of a corresponding sample as information indicating a location of a sample included in a coding unit should not be interpreted as limited to the above-described method, and various arithmetic operations that can use the coordinates of the sample It should be interpreted as a method.

According to an embodiment, the image decoding apparatus 100 may divide the current coding unit 600 into a plurality of coding units 620a, 620b, and 620c, and a predetermined one of the coding units 620a, 620b, and 620c The coding unit can be selected according to the criteria. For example, the image decoding apparatus 100 may select a coding unit 620b having a different size from among coding units 620a, 620b, and 620c.

According to an embodiment, the image decoding apparatus 100 is (xa, ya) coordinates, which is information indicating the location of the sample 630a at the upper left of the upper coding unit 620a, and a sample at the upper left of the middle coding unit 620b. Coding units 620a using (xb, yb) coordinates, which are information indicating the location of (630b), and (xc, yc) coordinates, which are information indicating the location of the sample 630c at the upper left of the lower coding unit 620c. , 620b, 620c) each width or height can be determined. The image decoding apparatus 100 uses coding units 620a and 620b using coordinates (xa, ya), (xb, yb), and (xc, yc) indicating the positions of coding units 620a, 620b, and 620c. , 620c) Each size can be determined. According to an embodiment, the image decoding apparatus 100 may determine the width of the upper coding unit 620a as the width of the current coding unit 600. The video decoding apparatus 100 may determine the height of the upper coding unit 620a as yb-ya. According to an embodiment, the image decoding apparatus 100 may determine the width of the middle coding unit 620b as the width of the current coding unit 600. The image decoding apparatus 100 may determine the height of the center coding unit 620b as yc-yb. According to an embodiment, the image decoding apparatus 100 may determine the width or height of the lower coding unit using the width or height of the current coding unit and the width and height of the upper coding unit 620a and the middle coding unit 620b. . The image decoding apparatus 100 may determine a coding unit having a different size from other coding units based on the width and height of the determined coding units 620a, 620b, and 620c. Referring to FIG. 6, the image decoding apparatus 100 may determine a coding unit 620b having a size different from that of the upper coding unit 620a and the lower coding unit 620c as a coding unit of a predetermined position. However, the above-described image decoding apparatus 100 determines a coding unit at a predetermined location using a size of a coding unit determined based on sample coordinates in the process of determining a coding unit having a different size from other coding units. Since it is merely a method, various processes of determining a coding unit at a predetermined location by comparing the sizes of coding units determined according to predetermined sample coordinates may be used.

The image decoding apparatus 100 includes (xd, yd) coordinates, which is information indicating the location of the sample 670a at the top left of the left coding unit 660a, and the location of the sample 670b at the top left of the middle coding unit 660b. Coding units 660a, 660b, and 660c using (xe, ye) coordinates, which are information representing, and (xf, yf) coordinates, which are information indicating the location of the sample 670c at the upper left of the right coding unit 660c. Each width or height can be determined. The image decoding apparatus 100 uses the coding units 660a and 660b using coordinates (xd, yd), (xe, ye), and (xf, yf) that indicate the positions of the coding units 660a, 660b, and 660c. , 660c) Each size can be determined.

According to an embodiment, the image decoding apparatus 100 may determine the width of the left coding unit 660a as xe-xd. The image decoding apparatus 100 may determine the height of the left coding unit 660a as the height of the current coding unit 650. According to an embodiment, the image decoding apparatus 100 may determine the width of the middle coding unit 660b as xf-xe. The image decoding apparatus 100 may determine the height of the middle coding unit 660b as the height of the current coding unit 600. According to an embodiment, the image decoding apparatus 100 may include a width or height of the right coding unit 660c, a width or height of the current coding unit 650, and a width and height of the left coding unit 660a and the middle coding unit 660b. Can be determined using. The video decoding apparatus 100 may determine a coding unit having a different size from other coding units based on the width and height of the determined coding units 660a, 660b, and 660c. Referring to FIG. 6, the image decoding apparatus 100 may determine a coding unit 660b as a coding unit of a predetermined position, having a size different from that of the left coding unit 660a and the right coding unit 660c. However, the above-described image decoding apparatus 100 determines a coding unit at a predetermined location using a size of a coding unit determined based on sample coordinates in the process of determining a coding unit having a different size from other coding units. Since it is merely a method, various processes of determining a coding unit at a predetermined location by comparing the sizes of coding units determined according to predetermined sample coordinates may be used.

However, the location of the sample considered in order to determine the location of the coding unit should not be interpreted as being limited to the upper left, and it can be interpreted that information about the location of any sample included in the coding unit can be used.

According to an embodiment, the image decoding apparatus 100 may select a coding unit at a predetermined position among odd coding units determined by dividing the current coding unit in consideration of the shape of the current coding unit. For example, if the current coding unit is a non-square shape having a width greater than a height, the image decoding apparatus 100 may determine a coding unit at a predetermined position according to a horizontal direction. That is, the image decoding apparatus 100 may determine one of the coding units having different positions in the horizontal direction and place restrictions on the coding unit. If the current coding unit is a non-square shape having a height higher than a width, the image decoding apparatus 100 may determine a coding unit at a predetermined position according to a vertical direction. That is, the image decoding apparatus 100 may determine one of the coding units having different positions in the vertical direction and place restrictions on the coding unit.

According to an embodiment, the image decoding apparatus 100 may use information indicating the location of each of the even numbered coding units to determine a coding unit of a predetermined position among the even numbered coding units. The image decoding apparatus 100 may determine an even number of coding units by dividing (binary splitting) the current coding unit, and determine a coding unit at a predetermined location using information about the positions of the even number of coding units. A specific process for this may be a process corresponding to a process of determining a coding unit of a predetermined position (for example, a center position) among the odd number of coding units described above with reference to FIG. 6, and thus will be omitted.

According to an embodiment, when a current coding unit having a non-square form is divided into a plurality of coding units, a predetermined coding unit for a predetermined position in a splitting process is determined in order to determine a coding unit at a predetermined position among a plurality of coding units. You can use the information. For example, the image decoding apparatus 100 may block information and split form stored in a sample included in a middle coding unit in a splitting process in order to determine a coding unit positioned in the center among coding units in which a plurality of current coding units are split. At least one of the mode information can be used.

Referring to FIG. 6, the image decoding apparatus 100 may divide the current coding unit 600 into a plurality of coding units 620a, 620b, and 620c based on the split mode mode information, and the plurality of coding units ( Among the 620a, 620b, and 620c), a coding unit 620b located in the center may be determined. Furthermore, the apparatus 100 for decoding an image may determine a coding unit 620b positioned in the center in consideration of a location where split mode mode information is obtained. That is, the split mode mode information of the current coding unit 600 may be obtained from the sample 640 located in the center of the current coding unit 600, and the current coding unit 600 may be based on the split mode mode information. When divided into a plurality of coding units 620a, 620b, and 620c, the coding unit 620b including the sample 640 may be determined as a coding unit located in the center. However, the information used for determining the coding unit located in the middle should not be interpreted as limited to the split mode mode information, and various types of information may be used in the process of determining the coding unit located in the middle.

According to an embodiment, predetermined information for identifying a coding unit at a predetermined location may be obtained from a predetermined sample included in a coding unit to be determined. Referring to FIG. 6, the image decoding apparatus 100 may include a coding unit (eg, divided into a plurality of units) at a predetermined position among a plurality of coding units 620a, 620b, and 620c determined by dividing the current coding unit 600. Split mode mode information obtained from a sample at a predetermined position in the current coding unit 600 (eg, a sample located in the center of the current coding unit 600) in order to determine a coding unit located in the middle among coding units. Can be used. That is, the video decoding apparatus 100 may determine the sample at the predetermined position in consideration of the block form of the current coding unit 600, and the video decoding apparatus 100 may determine a plurality of split current coding units 600. Among the coding units 620a, 620b, and 620c, a coding unit 620b including a sample in which predetermined information (eg, split mode mode information) can be obtained may be determined to place a predetermined limit. . Referring to FIG. 6, according to an embodiment, the image decoding apparatus 100 may determine a sample 640 located in the center of the current coding unit 600 as a sample from which predetermined information can be obtained, and the image decoding apparatus The (100) may place a predetermined restriction in the decoding process of the coding unit 620b in which the sample 640 is included. However, the location of a sample from which predetermined information can be obtained should not be interpreted as being limited to the above-described location, but may be interpreted as samples at any location included in the coding unit 620b to be determined in order to place a limit.

According to an embodiment, a location of a sample from which predetermined information can be obtained may be determined according to the type of the current coding unit 600. According to an embodiment, the block shape information may determine whether the shape of the current coding unit is square or non-square, and may determine a location of a sample from which predetermined information can be obtained according to the shape. For example, the image decoding apparatus 100 is located on a boundary that divides at least one of the width and height of the current coding unit in half by using at least one of information about the width and height of the current coding unit. The sample may be determined as a sample from which predetermined information can be obtained. For another example, when the block type information related to the current coding unit is in a non-square form, the video decoding apparatus 100 determines one of the samples adjacent to a boundary dividing the long side of the current coding unit in half. It can be determined as a sample from which information can be obtained.

According to an embodiment, when the current coding unit is divided into a plurality of coding units, the image decoding apparatus 100 may use split mode mode information to determine a coding unit at a predetermined position among a plurality of coding units. According to an embodiment, the image decoding apparatus 100 may obtain split mode mode information from a sample at a predetermined location included in a coding unit, and the image decoding apparatus 100 may generate a plurality of encodings generated by splitting a current coding unit. The units may be split using split mode mode information obtained from samples at predetermined positions included in each of the plurality of coding units. That is, the coding unit may be recursively partitioned using split mode mode information obtained from samples at a predetermined location included in each coding unit. The recursive splitting process of the coding unit has been described with reference to FIG. 5, so a detailed description will be omitted.

According to an embodiment, the image decoding apparatus 100 may determine at least one coding unit by dividing the current coding unit, and the order in which the at least one coding unit is decoded may be determined by a predetermined block (eg, the current coding unit). ).

7 illustrates an order in which a plurality of coding units are processed when the image decoding apparatus 100 determines a plurality of coding units by dividing a current coding unit according to an embodiment.

According to an embodiment, the image decoding apparatus 100 determines the second coding units 710a and 710b by dividing the first coding unit 700 in the vertical direction according to the split mode mode information, or the first coding unit 700. The second coding units 750a, 750b, 750c, and 750d may be determined by splitting the horizontal direction to determine the second coding units 730a and 730b, or by dividing the first coding unit 700 in the vertical and horizontal directions. have.

Referring to FIG. 7, the image decoding apparatus 100 may determine the order to process the second coding units 710a and 710b determined by dividing the first coding unit 700 in the vertical direction in the horizontal direction 710c. . The image decoding apparatus 100 may determine the processing order of the second coding units 730a and 730b determined by dividing the first coding unit 700 in the horizontal direction in the vertical direction 730c. After the image coding apparatus 100 processes the coding units positioned in one row, the second coding units 750a, 750b, 750c, and 750d determined by dividing the first coding unit 700 in the vertical direction and the horizontal direction are processed. The coding units positioned in the next row may be determined according to a predetermined order (for example, a raster scan order or a z scan order 750e).

According to an embodiment, the image decoding apparatus 100 may recursively divide coding units. Referring to FIG. 7, the image decoding apparatus 100 may determine a plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d by dividing the first coding unit 700, Each of the determined plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d may be recursively divided. A method of dividing the plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, 750d may be a method corresponding to a method of dividing the first coding unit 700. Accordingly, the plurality of coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, and 750d may be independently divided into a plurality of coding units. Referring to FIG. 7, the image decoding apparatus 100 may determine the second coding units 710a and 710b by dividing the first coding unit 700 in the vertical direction, and further, each of the second coding units 710a and 710b You can decide to split independently or not.

According to an embodiment, the image decoding apparatus 100 may split the second coding unit 710a on the left side into the third coding units 720a and 720b by splitting it horizontally, and the second coding unit 710b on the right side. ) May or may not divide.

According to an embodiment, a processing order of coding units may be determined based on a splitting process of coding units. In other words, the processing order of the divided coding units may be determined based on the processing order of the coding units immediately before being split. The image decoding apparatus 100 may independently determine the order in which the third coding units 720a and 720b determined by dividing the second coding unit 710a on the left are processed independently from the second coding unit 710b on the right. Since the second coding unit 710a on the left is split in the horizontal direction, and the third coding units 720a and 720b are determined, the third coding units 720a and 720b may be processed in the vertical direction 720c. Also, since the order in which the second coding unit 710a on the left and the second coding unit 710b on the right are processed corresponds to the horizontal direction 710c, the third coding unit included in the second coding unit 710a on the left side. After 720a and 720b are processed in the vertical direction 720c, the right coding unit 710b may be processed. Since the above-described content is for explaining a process in which a processing order is determined according to coding units before division, each coding unit should not be interpreted to be limited to the above-described embodiment. It should be interpreted as being used in a variety of ways that can be processed independently in sequence.

8 illustrates a process in which the video decoding apparatus 100 determines that the current coding unit is divided into an odd number of coding units when the coding units cannot be processed in a predetermined order according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may determine that the current coding unit is split into an odd number of coding units based on the obtained split mode mode information. Referring to FIG. 8, the first coding unit 800 in a square shape may be divided into second coding units 810a and 810b in a non-square shape, and the second coding units 810a and 810b may be independently selected from each other. It may be divided into three coding units 820a, 820b, 820c, 820d, and 820e. According to an embodiment, the image decoding apparatus 100 may determine a plurality of third coding units 820a and 820b by dividing the left coding unit 810a among the second coding units in a horizontal direction, and the right coding unit 810b ) May be divided into an odd number of third coding units 820c, 820d, and 820e.

According to an embodiment, the image decoding apparatus 100 determines whether the third coding units 820a, 820b, 820c, 820d, and 820e can be processed in a predetermined order to determine whether an odd number of coding units exist. Can decide. Referring to FIG. 8, the image decoding apparatus 100 may recursively divide the first coding unit 800 to determine third coding units 820a, 820b, 820c, 820d, and 820e. The image decoding apparatus 100 based on at least one of block type information and split type mode information, the first coding unit 800, the second coding units 810a, 810b, or the third coding units 820a, 820b, 820c , 820d, 820e) may be determined whether or not to be divided into odd number of coding units. For example, among the second coding units 810a and 810b, a coding unit positioned on the right side may be divided into an odd number of third coding units 820c, 820d, and 820e. The order in which the plurality of coding units included in the first coding unit 800 are processed may be a predetermined order (for example, a z-scan order 830), and the image decoding apparatus ( 100) may determine whether the third coding units 820c, 820d, and 820e determined by dividing the right second coding unit 810b into odd numbers satisfy a condition that can be processed according to the predetermined order.

According to an embodiment, the image decoding apparatus 100 satisfies a condition that the third coding units 820a, 820b, 820c, 820d, and 820e included in the first coding unit 800 may be processed according to a predetermined order. Whether or not the condition is divided in half by at least one of the width and height of the second coding units 810a and 810b according to the boundary of the third coding units 820a, 820b, 820c, 820d, and 820e. Related. For example, the third coding units 820a and 820b, which are determined by dividing the height of the left second coding unit 810a in a non-square shape in half, may satisfy the condition. The boundary of the third coding units 820c, 820d, and 820e determined by dividing the right second coding unit 810b into three coding units does not divide the width or height of the right second coding unit 810b in half. Therefore, it may be determined that the third coding units 820c, 820d, and 820e do not satisfy the condition. In the case of dissatisfaction with the condition, the image decoding apparatus 100 may determine that the scan order is disconnected, and determine that the right second coding unit 810b is divided into an odd number of coding units based on the determination result. According to an embodiment, when the image decoding apparatus 100 is divided into an odd number of coding units, a predetermined restriction may be placed on a coding unit at a predetermined position among the split coding units. Since it has been described through examples, detailed description will be omitted.

9 illustrates a process in which the image decoding apparatus 100 determines the at least one coding unit by dividing the first coding unit 900 according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may split the first coding unit 900 based on the split mode mode information obtained through the receiver 110. The first coding unit 900 having a square shape may be divided into coding units having four square shapes or may be divided into a plurality of coding units having a non-square shape. For example, referring to FIG. 9, when the first coding unit 900 is square and indicates that split mode mode information is divided into non-square coding units, the image decoding apparatus 100 may display the first coding unit 900. It can be divided into a plurality of non-square coding units. Specifically, when the split mode mode information indicates that the first coding unit 900 is divided into a horizontal direction or a vertical direction to determine an odd number of coding units, the image decoding apparatus 100 may include a square type first coding unit ( 900) may be divided into second coding units 910a, 910b, and 910c determined by splitting in the vertical direction as odd coding units or second coding units 920a, 920b, and 920c determined by splitting in the horizontal direction.

According to an embodiment, the image decoding apparatus 100 may include conditions in which second coding units 910a, 910b, 910c, 920a, 920b, and 920c included in the first coding unit 900 may be processed according to a predetermined order. It may be determined whether or not, and the condition is divided into at least one of the width and height of the first coding unit 900 according to the boundary of the second coding unit 910a, 910b, 910c, 920a, 920b, 920c. Whether it is related. Referring to FIG. 9, the boundary between the second coding units 910a, 910b, and 910c determined by dividing the square first coding unit 900 in the vertical direction divides the width of the first coding unit 900 in half. Therefore, it may be determined that the first coding unit 900 does not satisfy a condition that can be processed according to a predetermined order. Also, since the boundaries of the second coding units 920a, 920b, and 920c, which are determined by dividing the square first coding unit 900 in the horizontal direction, do not divide the width of the first coding unit 900 in half. It may be determined that one coding unit 900 does not satisfy a condition that can be processed according to a predetermined order. In the case of dissatisfaction with the condition, the image decoding apparatus 100 may determine that the scan sequence is disconnected, and determine that the first coding unit 900 is divided into an odd number of coding units based on the determination result. According to an embodiment, when the image decoding apparatus 100 is divided into an odd number of coding units, a predetermined restriction may be placed on a coding unit at a predetermined position among the split coding units. Since it has been described through examples, detailed description will be omitted.

According to an embodiment, the image decoding apparatus 100 may determine various types of coding units by dividing the first coding unit.

Referring to FIG. 9, the image decoding apparatus 100 may divide the first coding unit 900 in a square shape and the first coding unit 930 or 950 in a non-square shape into various coding units. .

FIG. 10 is a diagram illustrating that a second coding unit in a non-square shape determined by dividing a first coding unit 1000 by a video decoding apparatus 100 satisfies a predetermined condition according to an embodiment. It shows that the possible forms are limited.

According to an embodiment of the present disclosure, the image decoding apparatus 100 may replace the first coding unit 1000 having a square shape with the second coding unit 1010a having a non-square shape based on the split mode mode information obtained through the receiver 110. 1010b, 1020a, 1020b). The second coding units 1010a, 1010b, 1020a, and 1020b may be divided independently. Accordingly, the video decoding apparatus 100 may determine whether to divide or not split into a plurality of coding units based on split mode mode information related to each of the second coding units 1010a, 1010b, 1020a, and 1020b. According to an embodiment, the image decoding apparatus 100 may divide the left second coding unit 1010a of the non-square shape determined by dividing the first coding unit 1000 in the vertical direction in the horizontal direction, and then divide the third coding unit ( 1012a, 1012b). However, when the image decoding apparatus 100 divides the second left coding unit 1010a in the horizontal direction, the right second coding unit 1010b has the same horizontal direction as the left second coding unit 1010a is split. It can be limited so that it cannot be divided into. If the right second coding unit 1010b is split in the same direction and the third coding units 1014a and 1014b are determined, the left second coding unit 1010a and the right second coding unit 1010b are respectively in the horizontal direction. The third coding units 1012a, 1012b, 1014a, and 1014b may be determined by being independently divided. However, this is the same result as the image decoding apparatus 100 splitting the first coding unit 1000 into four square-type second coding units 1030a, 1030b, 1030c, and 1030d based on the split mode mode information. In terms of image decoding, it may be inefficient.

According to an embodiment, the image decoding apparatus 100 may divide a second coding unit 1020a or 1020b in a non-square shape determined by dividing the first coding unit 1000 in a horizontal direction in a vertical direction, and then a third coding unit. (1022a, 1022b, 1024a, 1024b) can be determined. However, when the video decoding apparatus 100 divides one of the second coding units (for example, the upper second coding unit 1020a) in the vertical direction, other second coding units (for example, lower ends) according to the aforementioned reason The coding unit 1020b) may restrict the upper second coding unit 1020a from being split in the same vertical direction as the split direction.

FIG. 11 is a diagram illustrating a process in which the image decoding apparatus 100 divides a square type coding unit when the split mode mode information cannot be divided into four square type coding units, according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may determine the second coding units 1110a, 1110b, 1120a, and 1120b by dividing the first coding unit 1100 based on the split mode mode information. The split mode mode information may include information on various types in which coding units can be split, but information on various types may not include information for splitting into four coding units in a square shape. According to the split mode mode information, the image decoding apparatus 100 does not divide the first coding unit 1100 in a square shape into four second coding units 1130a, 1130b, 1130c, and 1130d in a square shape. Based on the split mode mode information, the image decoding apparatus 100 may determine a second coding unit (1110a, 1110b, 1120a, 1120b, etc.) having a non-square shape.

According to an embodiment, the image decoding apparatus 100 may independently split the second coding units (1110a, 1110b, 1120a, 1120b, etc.) in a non-square form, respectively. Each of the second coding units 1110a, 1110b, 1120a, 1120b, etc. may be divided in a predetermined order through a recursive method, which is based on how the first coding unit 1100 is split based on the split mode mode information. It may be a corresponding partitioning method.

For example, the image decoding apparatus 100 may determine the third coding units 1112a and 1112b in a square shape by dividing the second coding unit 1110a on the left in the horizontal direction, and the second coding unit 1110b on the right. The third coding units 1114a and 1114b having a square shape may be determined by being split in a horizontal direction. Further, the image decoding apparatus 100 may determine the third coding units 1116a, 1116b, 1116c, and 1116d in a square shape by dividing both the left second coding unit 1110a and the right second coding unit 1110b in the horizontal direction. have. In this case, the coding unit may be determined in the same form as the first coding unit 1100 is divided into four square second coding units 1130a, 1130b, 1130c, and 1130d.

For another example, the image decoding apparatus 100 may determine the third coding units 1122a and 1122b in a square shape by dividing the upper second coding unit 1120a in the vertical direction, and the lower second coding unit 1120b. ) Is divided in the vertical direction to determine the third coding units 1124a and 1124b in a square shape. Furthermore, the image decoding apparatus 100 may determine the third coding units 1126a, 1126b, 1126a, and 1126b in a square shape by dividing both the upper second coding unit 1120a and the lower second coding unit 1120b in the vertical direction. have. In this case, the coding unit may be determined in the same form as the first coding unit 1100 is divided into four square second coding units 1130a, 1130b, 1130c, and 1130d.

12 illustrates that a processing order among a plurality of coding units may vary according to a splitting process of coding units according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may split the first coding unit 1200 based on the split mode mode information. When the block shape is a square and the split mode information indicates that the first coding unit 1200 is split in at least one of a horizontal direction and a vertical direction, the image decoding apparatus 100 displays the first coding unit 1200. The second coding unit (eg, 1210a, 1210b, 1220a, 1220b, etc.) may be determined by splitting. Referring to FIG. 12, the second coding units 1210a, 1210b, 1220a, and 1220b of the non-square shape determined by dividing the first coding unit 1200 only in the horizontal direction or the vertical direction are based on split mode mode information for each of them. Can be divided independently. For example, the image decoding apparatus 100 splits the second coding units 1210a and 1210b generated by dividing the first coding unit 1200 in the vertical direction, respectively, into third horizontal coding units 1216a and 1216b, 1216c and 1216d), and the second coding units 1220a and 1220b generated by dividing the first coding unit 1200 in the horizontal direction are split in the horizontal direction, respectively, and the third coding units 1226a, 1226b, and 1226c. , 1226d). Since the splitting process of the second coding units 1210a, 1210b, 1220a, and 1220b is described above with reference to FIG. 11, a detailed description thereof will be omitted.

According to an embodiment, the image decoding apparatus 100 may process coding units according to a predetermined order. The characteristics of the processing of the coding unit according to a predetermined order have been described above with reference to FIG. 7, so a detailed description thereof will be omitted. Referring to FIG. 12, the image decoding apparatus 100 divides the first coding unit 1200 in a square shape, and thereby generates three fourth coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d. ). According to an embodiment, the image decoding apparatus 100 may process a third coding unit 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d according to the form in which the first coding unit 1200 is divided. Can decide.

According to an embodiment, the image decoding apparatus 100 determines the third coding units 1216a, 1216b, 1216c, and 1216d by dividing the second coding units 1210a and 1210b generated by being split in the vertical direction, respectively, in the horizontal direction. The video decoding apparatus 100 may first process the third coding units 1216a and 1216c included in the left second coding unit 1210a in the vertical direction, and then include the right second coding unit 1210b. The third coding units 1216a, 1216b, 1216c, and 1216d may be processed according to an order 1217 of processing the third coding units 1216b and 1216d in the vertical direction.

According to an embodiment, the image decoding apparatus 100 determines the third coding units 1226a, 1226b, 1226c, and 1226d by dividing the second coding units 1220a and 1220b generated by being split in the horizontal direction in the vertical direction, respectively. The video decoding apparatus 100 may first process the third coding units 1226a and 1226b included in the upper second coding unit 1220a in the horizontal direction, and then include the lower second coding units 1220b. The third coding units 1226a, 1226b, 1226c, and 1226d may be processed according to a procedure 1227 for processing the third coding units 1226c and 1226d in the horizontal direction.

Referring to FIG. 12, the second coding units 1210a, 1210b, 1220a, and 1220b are divided, so that the third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d may be determined. have. The second coding units 1210a and 1210b determined by splitting in the vertical direction and the second coding units 1220a and 1220b determined by splitting in the horizontal direction are split in different forms, but the third coding units 1216a determined later. , 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d), the first coding unit 1200 is divided into coding units having the same type. Accordingly, the image decoding apparatus 100 divides the coding units recursively through different processes based on the split mode mode information, so that even if the coding units of the same type are determined as a result, a plurality of coding units determined in the same type are different. It can be processed in order.

13 is a diagram illustrating a process in which a depth of a coding unit is determined as a shape and a size of a coding unit change when a coding unit is recursively divided and a plurality of coding units are determined according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may determine the depth of the coding unit according to a predetermined criterion. For example, the predetermined criterion may be the length of the long side of the coding unit. When the length of the long side of the current coding unit is split by 2n (n>0) times than the length of the long side of the coding unit before being split, the image decoding apparatus 100 may have a depth greater than that of the coding unit before being split. It can be determined that the depth is increased by n. Hereinafter, a coding unit having an increased depth is expressed as a coding unit of a lower depth.

Referring to FIG. 13, according to an embodiment, the image decoding apparatus 100 may be configured to have a square shape based on block shape information indicating that it is a square shape (for example, block shape information may indicate '0: SQUARE'). The first coding unit 1300 may be split to determine a second coding unit 1302, a third coding unit 1304, and the like of a lower depth. If the size of the first coding unit 1300 in the square form is 2Nx2N, the second coding unit 1302 determined by dividing the width and height of the first coding unit 1300 by 1/2 times may have a size of NxN. have. Furthermore, the third coding unit 1304 determined by dividing the width and height of the second coding unit 1302 into 1/2 size may have a size of N/2xN/2. In this case, the width and height of the third coding unit 1304 are 1/4 times the first coding unit 1300. When the depth of the first coding unit 1300 is D, the depth of the second coding unit 1302 that is 1/2 times the width and height of the first coding unit 1300 may be D+1, and the first coding unit A depth of the third coding unit 1304 that is 1/4 times the width and height of (1300) may be D+2.

According to an embodiment, block shape information indicating a non-square shape (eg, block shape information is '1: NS_VER' in which a height is longer than a width, or'N_square' in which a width is longer than a height) 2: NS_HOR′), the video decoding apparatus 100 divides the first coding unit 1310 or 1320 which is a non-square shape, and the second coding unit 1312 or 1322 of a lower depth, The third coding unit 1314 or 1324 may be determined.

The image decoding apparatus 100 may determine a second coding unit (eg, 1302, 1312, 1322, etc.) by dividing at least one of a width and a height of the first coding unit 1310 having an Nx2N size. That is, the image decoding apparatus 100 may divide the first coding unit 1310 in the horizontal direction to determine a second coding unit 1302 of NxN size or a second coding unit 1322 of NxN/2 size, The second coding unit 1312 having an N/2×N size may be determined by dividing it in a horizontal direction and a vertical direction.

According to an embodiment, the image decoding apparatus 100 determines a second coding unit (eg, 1302, 1312, 1322, etc.) by dividing at least one of a width and a height of the first coding unit 1320 having a size of 2NxN. It might be. That is, the image decoding apparatus 100 may divide the first coding unit 1320 in the vertical direction to determine a second coding unit 1302 having an NxN size or a second coding unit 1312 having an N/2xN size, The second coding unit 1322 having an NxN/2 size may be determined by dividing it in a horizontal direction and a vertical direction.

According to an embodiment, the image decoding apparatus 100 determines a third coding unit (eg, 1304, 1314, 1324, etc.) by dividing at least one of the width and height of the NxN-sized second coding unit 1302. It might be. That is, the video decoding apparatus 100 divides the second coding unit 1302 in the vertical direction and the horizontal direction to determine the third coding unit 1304 having an N/2xN/2 size, or an N/4xN/2 sized coding unit. The third coding unit 1314 may be determined, or the third coding unit 1324 having an N/2×N/4 size may be determined.

According to an embodiment, the image decoding apparatus 100 divides at least one of a width and a height of the second coding unit 1312 having an N/2xN size, and a third coding unit (for example, 1304, 1314, 1324, etc.) You can also decide That is, the image decoding apparatus 100 divides the second coding unit 1312 in the horizontal direction, thereby forming a third coding unit 1304 having an N/2xN/2 size or a third coding unit 1324 having an N/2xN/4 size. ) Or split in a vertical direction and a horizontal direction to determine a third coding unit 1314 having an N/4xN/2 size.

According to an embodiment, the image decoding apparatus 100 divides at least one of the width and height of the second coding unit 1322 having an NxN/2 size, and thus a third coding unit (eg, 1304, 1314, 1324, etc.) You can also decide That is, the image decoding apparatus 100 divides the second coding unit 1322 in the vertical direction, and thus a third coding unit 1304 having an N/2xN/2 size or a third coding unit having an N/4xN/2 size 1314 ) Or split in a vertical direction and a horizontal direction to determine a third coding unit 1324 having an N/2×N/4 size.

According to an embodiment, the apparatus 100 for decoding an image may divide a coding unit having a square shape (eg, 1300, 1302, 1304) in a horizontal direction or a vertical direction. For example, the first coding unit 1320 having a size of 2Nx2N is determined by dividing the first coding unit 1300 having a size of 2Nx2N in the vertical direction, or the first coding unit 1320 having a size of 2NxN by splitting in the horizontal direction. Can. When the depth is determined based on the length of the longest side of the coding unit according to an embodiment, the depth of the coding unit determined by dividing the first coding unit 1300 having a size of 2Nx2N in the horizontal direction or the vertical direction is determined by the first coding The depth of the unit 1300 may be the same.

According to an embodiment, the width and height of the third coding unit 1314 or 1324 may correspond to 1/4 times the first coding unit 1310 or 1320. When the depth of the first coding unit 1310 or 1320 is D, the depth of the second coding unit 1312 or 1322 that is 1/2 times the width and height of the first coding unit 1310 or 1320 may be D+1. The depth of the third coding unit 1314 or 1324 that is 1/4 times the width and height of the first coding unit 1310 or 1320 may be D+2.

14 is a diagram for a depth and a coding index (part index, PID) that can be determined according to the type and size of coding units, according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may determine the second coding unit of various types by dividing the first coding unit 1400 having a square shape. Referring to FIG. 14, the image decoding apparatus 100 divides the first coding unit 1400 into at least one of a vertical direction and a horizontal direction according to the split mode mode information, and then the second coding units 1402a, 1402b, and 1404a , 1404b, 1406a, 1406b, 1406c, 1406d). That is, the image decoding apparatus 100 may determine the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, and 1406d based on the split mode mode information for the first coding unit 1400. .

According to an embodiment, the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, and 1406d determined according to the split mode mode information for the first coding unit 1400 having a square shape have a long side length Based on the depth can be determined. For example, since the length of one side of the first coding unit 1400 in the square shape and the length of the long side of the second coding unit 1402a, 1402b, 1404a, and 1404b in the non-square shape are the same, the first coding unit ( 1400) and the non-square form of the second coding units 1402a, 1402b, 1404a, and 1404b may be considered to have the same depth as D. On the other hand, when the image decoding apparatus 100 divides the first coding unit 1400 into four square-type second coding units 1406a, 1406b, 1406c, and 1406d based on the split mode mode information, the square-shaped Since the length of one side of the second coding unit 1406a, 1406b, 1406c, and 1406d is 1/2 times the length of one side of the first coding unit 1400, the length of one side of the second coding unit 1406a, 1406b, 1406c, 1406d The depth may be a depth of D+1 that is one depth lower than D, which is the depth of the first coding unit 1400.

According to an embodiment of the present disclosure, the image decoding apparatus 100 divides the first coding unit 1410 having a height greater than a width in a horizontal direction according to the split mode mode information, thereby providing a plurality of second coding units 1412a, 1412b, and 1414a. , 1414b, 1414c). According to an embodiment of the present disclosure, the image decoding apparatus 100 divides the first coding unit 1420 having a width longer than a height in a vertical direction according to the split mode mode information, thereby providing a plurality of second coding units 1422a, 1422b, and 1424a. , 1424b, 1424c).

Second coding units 1412a, 1412b, 1414a, 1414b, 1414c. 1422a, 1422b, 1424a, which are determined according to split mode mode information for the first coding unit 1410 or 1420 in a non-square form according to an embodiment 1424b, 1424c) may determine the depth based on the length of the long side. For example, the length of one side of the second coding units 1412a and 1412b in the square shape is 1/2 times the length of one side of the first coding unit 1410 in the non-square shape having a height greater than the width, so that the square The depth of the second coding units 1412a and 1412b in the form is D+1, which is a depth lower than a depth D of the first coding unit 1410 in the non-square form.

Furthermore, the image decoding apparatus 100 may divide the first coding unit 1410 in a non-square shape into odd numbered second coding units 1414a, 1414b, and 1414c based on the split mode mode information. The odd number of second coding units 1414a, 1414b, 1414c may include non-square second coding units 1414a, 1414c and square second coding units 1414b. In this case, the length of one side of the second coding unit 1414c of the non-square shape and the length of one side of the second coding unit 1414b of the square shape are 1/ of the length of one side of the first coding unit 1410. Since it is twice, the depth of the second coding units 1414a, 1414b, and 1414c may be a depth of D+1 that is one depth lower than D, which is the depth of the first coding unit 1410. The image decoding apparatus 100 is a method corresponding to the above method for determining the depth of coding units related to the first coding unit 1410, and is associated with the first coding unit 1420 having a non-square shape having a width greater than a height. The depth of coding units may be determined.

According to an embodiment of the present invention, the image decoding apparatus 100 determines an index (PID) for distinguishing the divided coding units. If the odd numbered coding units are not the same size, the size ratio between the coding units is determined. The index can be determined based on this. Referring to FIG. 14, among the coding units 1414a, 1414b, and 1414c, which are divided into odd numbers, the coding unit 1414b located in the center has the same width as other coding units 1414a, 1414c but different heights. It may be twice the height of the fields 1414a, 1414c. That is, in this case, the coding unit 1414b located in the center may include two of the other coding units 1414a and 1414c. Accordingly, if the index (PID) of the coding unit 1414b positioned at the center is 1 according to the scan order, the coding unit 1414c positioned at the next order may be 3 with an index of 2. That is, there may be discontinuity in the value of the index. According to an embodiment, the image decoding apparatus 100 may determine whether odd numbered coding units are not the same size as each other based on the existence of discontinuity of an index for distinguishing between the split coding units.

According to an embodiment of the present disclosure, the image decoding apparatus 100 may determine whether it is divided into a specific partitioning type based on an index value for distinguishing a plurality of coding units determined by being split from the current coding unit. Referring to FIG. 14, the image decoding apparatus 100 determines an even number of coding units 1412a and 1412b by dividing a rectangular first coding unit 1410 whose height is longer than a width or an odd number of coding units 1414a and 1414b. , 1414c). The image decoding apparatus 100 may use an index (PID) indicating each coding unit to distinguish each of the plurality of coding units. According to an embodiment, the PID may be obtained from a sample at a predetermined position of each coding unit (eg, an upper left sample).

According to an embodiment, the image decoding apparatus 100 may determine an encoding unit at a predetermined location among the determined encoding units by using an index for classifying the encoding units. According to an embodiment, when the split mode mode information for the first coding unit 1410 in a rectangular shape having a height greater than a width indicates that the split mode mode information is divided into three coding units, the image decoding apparatus 100 may include a first coding unit 1410. Can be divided into three coding units 1414a, 1414b, and 1414c. The video decoding apparatus 100 may allocate an index for each of the three coding units 1414a, 1414b, and 1414c. The image decoding apparatus 100 may compare an index for each coding unit to determine a middle coding unit among coding units divided into odd numbers. The image decoding apparatus 100 encodes a coding unit 1414b having an index corresponding to a middle value among indexes based on an index of coding units, and encoding of a center position among coding units determined by splitting the first coding unit 1410. It can be determined as a unit. According to an embodiment, the image decoding apparatus 100 may determine an index based on a size ratio between coding units when the coding units are not the same size as each other in determining an index for dividing the divided coding units. . Referring to FIG. 14, the coding unit 1414b generated by dividing the first coding unit 1410 is of coding units 1414a and 1414c having the same width but different heights from other coding units 1414a and 1414c. It can be twice the height. In this case, if the index (PID) of the coding unit 1414b positioned in the center is 1, the coding unit 1414c positioned in the next order may be 3 with an index of 2. In such a case, if the index is uniformly increased and the increase width is different, the image decoding apparatus 100 may determine that the image decoding apparatus 100 is divided into a plurality of coding units including coding units having different sizes from other coding units. When the split mode mode information is divided into odd number of coding units, the image decoding apparatus 100 has a different coding unit from a coding unit having a predetermined position (for example, a middle coding unit) among odd coding units having different sizes. In the form, the current coding unit can be divided. In this case, the image decoding apparatus 100 may determine a coding unit having a different size using an index (PID) for the coding unit. However, the above-described index, the size or position of the coding unit at a predetermined position to be determined is specific to explain one embodiment, and should not be interpreted as being limited thereto, and the position and size of various indexes and coding units can be used. Should be interpreted.

According to an embodiment, the image decoding apparatus 100 may use a predetermined data unit in which recursive division of the coding unit starts.

15 illustrates that a plurality of coding units are determined according to a plurality of predetermined data units included in a picture according to an embodiment.

According to an embodiment, a predetermined data unit may be defined as a data unit in which a coding unit starts to be recursively divided using split mode mode information. That is, it may correspond to a coding unit of a highest depth used in a process in which a plurality of coding units for splitting a current picture are determined. Hereinafter, for convenience of description, the predetermined data unit will be referred to as a reference data unit.

According to an embodiment, the reference data unit may represent a predetermined size and shape. According to an embodiment, the reference coding unit may include samples of MxN. Here, M and N may be the same as each other, or may be integers represented by a power of two. That is, the reference data unit may represent a square or non-square shape, and may be divided into an integer number of coding units.

According to an embodiment, the image decoding apparatus 100 may divide the current picture into a plurality of reference data units. According to an embodiment, the image decoding apparatus 100 may divide a plurality of reference data units for dividing a current picture using split mode mode information for each reference data unit. The division process of the reference data unit may correspond to a division process using a quad-tree structure.

According to an embodiment, the image decoding apparatus 100 may determine in advance the minimum size that the reference data unit included in the current picture can have. Accordingly, the image decoding apparatus 100 may determine the reference data units of various sizes having a size equal to or greater than the minimum size, and may determine at least one coding unit using split mode mode information based on the determined reference data units. .

Referring to FIG. 15, the image decoding apparatus 100 may use a reference coding unit 1500 in a square shape, or may use a reference coding unit 1502 in a non-square shape. According to an embodiment, the shape and size of the reference coding unit may include various data units (eg, sequences, pictures, slices, slice segments (eg, sequences) that may include at least one reference coding unit. slice segment, maximum coding unit, etc.).

According to an embodiment, the receiver 110 of the image decoding apparatus 100 may obtain at least one of information on a type of a reference coding unit and information on a size of a reference coding unit from a bitstream for each of the various data units. . The process of determining at least one coding unit included in the square type reference coding unit 1500 is described through a process in which the current coding unit 300 of FIG. 3 is divided, and the non-square type reference coding unit 1502 The process of determining at least one coding unit included in) has been described through the process of dividing the current coding unit 400 or 450 of FIG. 4, so a detailed description thereof will be omitted.

According to an embodiment, the image decoding apparatus 100 may index the size and shape of the reference coding unit in order to determine the size and shape of the reference coding unit according to some predetermined data units based on predetermined conditions Can be used. That is, the receiving unit 110 is a predetermined condition (for example, a data unit having a size equal to or less than a slice) among the various data units (eg, sequence, picture, slice, slice segment, maximum coding unit, etc.) from the bitstream. As a data unit that satisfies, for each slice, slice segment, and maximum coding unit, only an index for identifying the size and shape of the reference coding unit may be obtained. The image decoding apparatus 100 may determine the size and shape of a reference data unit for each data unit that satisfies the predetermined condition by using an index. When the information on the type of the reference coding unit and the information on the size of the reference coding unit are obtained and used from the bitstream for each data unit of a relatively small size, the utilization efficiency of the bitstream may not be good, so the type of the reference coding unit Instead of directly acquiring information about the size of the information and the size of the reference coding unit, the index can be obtained and used. In this case, at least one of the size and shape of the reference coding unit corresponding to the index indicating the size and shape of the reference coding unit may be predetermined. That is, the image decoding apparatus 100 selects at least one of the size and shape of the predetermined reference coding unit according to the index, thereby selecting at least one of the size and shape of the reference coding unit included in the data unit that is the basis of index acquisition. Can decide.

According to an embodiment, the image decoding apparatus 100 may use at least one reference coding unit included in one largest coding unit. That is, the largest coding unit for splitting an image may include at least one reference coding unit, and a coding unit may be determined through a recursive splitting process of each reference coding unit. According to an embodiment, at least one of the width and height of the maximum coding unit may correspond to an integer multiple of the width and height of the reference coding unit. According to an embodiment, the size of the reference coding unit may be a size obtained by dividing the largest coding unit n times according to a quad tree structure. That is, the image decoding apparatus 100 may determine the reference coding unit by dividing the largest coding unit n times according to a quad tree structure, and the reference coding unit according to various embodiments at least among block type information and split type mode information. It can be divided based on one.

16 illustrates a processing block serving as a reference for determining a determination order of a reference coding unit included in the picture 1600 according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may determine at least one processing block for dividing a picture. The processing block is a data unit including at least one reference coding unit that splits an image, and at least one reference coding unit included in the processing block may be determined in a specific order. That is, the determination order of the at least one reference coding unit determined in each processing block may correspond to one of various types of order in which the reference coding unit can be determined, and the reference coding unit determination order determined in each processing block May be different for each processing block. Decision order of the reference coding unit determined for each processing block includes raster scan, Z-scan, N-scan, up-right diagonal scan, and horizontal scan ( It may be one of various sequences, such as a horizontal scan and a vertical scan, but the order that can be determined should not be interpreted as being limited to the scan sequences.

According to an embodiment, the image decoding apparatus 100 may obtain information about the size of the processing block to determine the size of at least one processing block included in the image. The image decoding apparatus 100 may obtain information about the size of a processing block from a bitstream and determine the size of at least one processing block included in the image. The size of the processing block may be a predetermined size of a data unit indicated by information about the size of the processing block.

According to an embodiment, the reception unit 110 of the image decoding apparatus 100 may acquire information about the size of a processing block from a bitstream for each specific data unit. For example, information on the size of a processing block may be obtained from a bitstream in units of data such as an image, a sequence, a picture, a slice, and a slice segment. That is, the receiver 110 may obtain information on the size of a processing block from a bitstream for each of the data units, and the image decoding apparatus 100 may divide a picture using information about the size of the obtained processing block. The size of one processing block may be determined, and the size of such a processing block may be an integer multiple of a reference coding unit.

According to an embodiment, the image decoding apparatus 100 may determine the sizes of the processing blocks 1602 and 1612 included in the picture 1600. For example, the image decoding apparatus 100 may determine the size of the processing block based on information about the size of the processing block obtained from the bitstream. Referring to FIG. 16, the image decoding apparatus 100 sets the horizontal size of the processing blocks 1602 and 1612 to four times the horizontal size of the reference coding unit and the vertical size to four times the vertical size of the reference coding unit, according to an embodiment. Can decide. The image decoding apparatus 100 may determine an order in which at least one reference coding unit is determined in at least one processing block.

According to an embodiment, the image decoding apparatus 100 may determine each processing block 1602 and 1612 included in the picture 1600 based on the size of the processing block, and include the processing blocks 1602 and 1612 The determination order of the at least one reference coding unit may be determined. According to an embodiment, the determination of the reference coding unit may include determining the size of the reference coding unit.

According to an embodiment, the image decoding apparatus 100 may obtain information on a decision order of at least one reference coding unit included in at least one processing block from a bitstream, and based on the obtained decision order information Accordingly, an order in which at least one reference coding unit is determined may be determined. The information about the decision order may be defined in the order or direction in which the reference coding units are determined in the processing block. That is, the order in which the reference coding units are determined may be independently determined for each processing block.

According to an embodiment, the image decoding apparatus 100 may obtain information on a determination order of a reference coding unit for each specific data unit from a bitstream. For example, the receiver 110 may obtain information on a determination order of a reference coding unit from a bitstream for each data unit such as an image, a sequence, a picture, a slice, a slice segment, and a processing block. Since the information on the decision order of the reference coding unit indicates the reference coding unit decision order in the processing block, information on the decision order can be obtained for each specific data unit including an integer number of processing blocks.

The video decoding apparatus 100 may determine at least one reference coding unit based on the order determined according to an embodiment.

According to an embodiment, the receiver 110 may obtain information on a reference coding unit determination order as information related to processing blocks 1602 and 1612 from a bitstream, and the image decoding apparatus 100 may include the processing block ( 1602, 1612) may determine an order of determining at least one reference coding unit, and may determine at least one reference coding unit included in the picture 1600 according to an order of determining coding units. Referring to FIG. 16, the image decoding apparatus 100 may determine a determination order 1604 and 1614 of at least one reference coding unit associated with each processing block 1602 and 1612. For example, when information on a decision order of a reference coding unit is obtained for each processing block, a reference coding unit decision order associated with each processing block 1602 and 1612 may be different for each processing block. When the reference coding unit determination order 1604 related to the processing block 1602 is a raster scan order, the reference coding units included in the processing block 1602 may be determined according to the raster scan order. On the other hand, when the reference coding unit determination order 1614 associated with another processing block 1612 is in the reverse order of the raster scan order, the reference coding unit included in the processing block 1612 may be determined according to the reverse order of the raster scan order.

The video decoding apparatus 100 may decode the determined at least one reference coding unit, according to an embodiment. The image decoding apparatus 100 may decode the image based on the reference coding unit determined through the above-described embodiment. The method of decoding the reference coding unit may include various methods of decoding the image.

According to an embodiment, the image decoding apparatus 100 may obtain and use block shape information indicating a shape of a current coding unit or split shape mode information indicating a method of splitting a current coding unit from a bitstream. The split mode mode information may be included in a bitstream associated with various data units. For example, the video decoding apparatus 100 may include a sequence parameter set, a picture parameter set, a video parameter set, a slice header, and a slice segment header. The segmentation mode mode information included in the segment header) may be used. Furthermore, the image decoding apparatus 100 may obtain and use a syntax element corresponding to block type information or split type mode information from a bit stream for each largest coding unit, a reference coding unit, and a processing block, from a bit stream.

Hereinafter, a method of determining a division rule according to an embodiment of the present disclosure will be described in detail.

The image decoding apparatus 100 may determine a division rule of an image. The segmentation rule may be predetermined between the video decoding apparatus 100 and the video encoding apparatus 2200. The image decoding apparatus 100 may determine a division rule of the image based on the information obtained from the bitstream. The video decoding apparatus 100 includes a sequence parameter set, a picture parameter set, a video parameter set, a slice header, and a slice segment header A division rule may be determined based on information obtained from at least one. The image decoding apparatus 100 may differently determine a division rule according to a frame, a slice, a temporal layer, a maximum coding unit, or coding units.

The video decoding apparatus 100 may determine a division rule based on the block type of the coding unit. The block shape may include the size, shape, ratio of width and height, and direction of the coding unit. The video encoding apparatus 2200 and the video decoding apparatus 100 may determine in advance to determine a division rule based on a block type of a coding unit. However, it is not limited thereto. The video decoding apparatus 100 may determine a division rule based on information obtained from the bitstream received from the video encoding apparatus 2200.

The shape of the coding unit may include a square and a non-square. When the width and height of the coding unit are the same, the image decoding apparatus 100 may determine the shape of the coding unit as a square. Also, . If the widths and heights of the coding units are not the same, the image decoding apparatus 100 may determine the shape of the coding unit as a non-square.

The size of the coding unit may include various sizes of 4x4, 8x4, 4x8, 8x8, 16x4, 16x8, ..., 256x256. The size of the coding unit may be classified according to the length of the long side, the length or the width of the short side of the coding unit. The video decoding apparatus 100 may apply the same division rule to coding units classified into the same group. For example, the image decoding apparatus 100 may classify coding units having the same long side length into the same size. Also, the image decoding apparatus 100 may apply the same division rule to coding units having the same long side length.

The ratio of the width and height of the coding unit is 1:2, 2:1, 1:4, 4:1, 1:8, 8:1, 1:16, 16:1, 32:1 or 1:32, etc. It can contain. Also, the direction of the coding unit may include a horizontal direction and a vertical direction. The horizontal direction may indicate a case where the length of the width of the coding unit is longer than the length of the height. The vertical direction may represent a case in which the length of the width of the coding unit is shorter than the length of the height.

The video decoding apparatus 100 may adaptively determine a division rule based on the size of a coding unit. The video decoding apparatus 100 may differently determine an allowable split mode mode based on the size of the coding unit. For example, the video decoding apparatus 100 may determine whether division is allowed based on the size of the coding unit. The image decoding apparatus 100 may determine a split direction according to the size of the coding unit. The image decoding apparatus 100 may determine an allowable division type according to the size of the coding unit.

The determination of the division rule based on the size of the coding unit may be a predetermined division rule between the image encoding apparatus 2200 and the image decoding apparatus 100. Also, the video decoding apparatus 100 may determine a division rule based on the information obtained from the bitstream.

The video decoding apparatus 100 may adaptively determine a division rule based on the location of the coding unit. The video decoding apparatus 100 may adaptively determine a division rule based on a position occupied by the coding unit in the image.

Also, the apparatus 100 for decoding an image may determine a splitting rule so that coding units generated by different splitting paths do not have the same block shape. However, the present invention is not limited thereto, and coding units generated with different split paths may have the same block shape. Coding units generated with different split paths may have different decoding processing sequences. Since the decoding processing procedure has been described with reference to FIG. 12, detailed description is omitted.

Hereinafter, an available block among neighboring blocks neighboring the current block in the same frame as the current block is determined according to an embodiment disclosed herein with reference to FIGS. 17 to 20 and local luminance compensation information is available from the available block. A method and apparatus for encoding and decoding a video that applies a local luminance compensation by deriving and determining a local luminance compensation model based on the local luminance compensation information and using the local luminance compensation model determined for the current block is described above.

17 is a block diagram of a video decoding apparatus 1700 according to an embodiment.

The video decoding apparatus 1700 according to an embodiment may include a memory 1710 and at least one processor 1720 connected to the memory 1710. The operations of the video decoding apparatus 1700 according to an embodiment may operate as individual processors or may be operated under the control of a central processor. Also, the memory 1710 of the video decoding apparatus 1700 may store data received from the outside and data generated by the processor, for example, local luminance compensation information of a neighboring block.

The processor 1720 of the video decoding apparatus 1700 determines an available block among neighboring blocks neighboring the current block in the same frame as the current block, derives local luminance compensation information from the available block, and the local A local luminance compensation model may be determined based on luminance compensation information, and local luminance compensation may be applied using the local luminance compensation model determined for the current block.

Hereinafter, with reference to FIG. 18, the video decoding apparatus 1700 determines an available block among neighboring blocks adjacent to the current block in the same frame as the current block, and local luminance compensation information from the available block Detailed operations for a video decoding method for deriving them, determining a local luminance compensation model based on the local luminance compensation information, and applying local luminance compensation using the determined local luminance compensation model to the current block will be described in detail.

18 is a flowchart of a video decoding method according to an embodiment.

Referring to FIG. 18, in step s1810, the video decoding apparatus 1700 may determine an available block among neighboring blocks neighboring the current block in the same frame as the current block.

According to an embodiment, neighboring blocks may be adjacent to at least one of the left, top, top, right, and right sides of the current block.

According to another embodiment, neighboring blocks may be adjacent to at least one of the left side, the top left side, and the top side of the current block.

According to another embodiment, neighboring blocks may be adjacent to at least one of the top, right, and right sides of the current block.

Referring back to FIG. 18, in step s1830, the video decoding apparatus 1700 may derive local luminance compensation information from the available block.

In step s1850, a local luminance compensation model may be determined based on the local luminance compensation information.

In step s1870, local luminance compensation may be applied using the local luminance compensation model determined for the current block. Specifically, a final prediction pixel to which local luminance compensation is applied may be obtained by applying a local luminance compensation model to a sample obtained from motion compensation of a current block.

21A and 21B show an example of a modeling process for applying local luminance compensation using predictive pixels and reconstructed pixels.

Referring to FIG. 21A, the x-axis may be a pixel value of predicted pixels of the current block of the current frame, and the y-axis may be a pixel value of reconstructed pixels of the current block. The predicted pixel and reconstructed pixel of the current block may be pixels located at the edges of the current block (eg, the left, lower, and upper edges of the current block). The total range of pixel values may be 0 to 1023. The points indicated in the graph for model generation shown in FIG. 21A indicate the relationship between the predicted pixel of the current block of the current frame and the reconstructed pixel of the current block. A local luminance compensation model for the current coding unit may be generated by performing linear regression on these points. The generated local luminance compensation model may be used for local luminance compensation of future neighboring coding units neighboring the current coding unit. Specifically, referring to FIG. 21B, as a result of FIG. 21A, a straight line graph of applying a local luminance compensation model may be completed. Accordingly, local luminance compensation information of the stored neighboring coding unit can be derived to determine a local luminance compensation model for the current coding unit based on the local luminance compensation information. By applying the determined local luminance compensation model to the prediction sample obtained from motion compensation of the current coding unit, a final prediction pixel of the current coding unit to which local luminance compensation is applied can be obtained. For example, the local luminance compensation model may be determined by y=a*x+b, and the local luminance compensation parameter may be determined by scale factor a and offset b.

According to an embodiment, the local luminance compensation information may include a local luminance compensation parameter. The local luminance compensation parameter may be calculated using the predicted sample of the current block of the current frame and the reconstructed sample of the current block, and stored in the memory. The local luminance compensation parameter is calculated and stored in memory using the predicted and reconstructed samples of the current block of the current frame, thereby accessing the reconstructed pixels of the block neighboring the current block of the current frame and the reconstructed pixels of the reference frame. Can be removed. The prediction sample of the current block used for local luminance compensation modeling is a pixel obtained immediately after motion compensation and a pixel before other refinements or tools are applied.

22 illustrates local luminance compensation parameters according to an embodiment.

Referring to FIG. 22, the local luminance compensation model may be a linear model, and in the case of a linear model, a scale factor (int a[REFP_NUM][N_C][IC_TOTAL-SIDES]) and an offset (int b[REFP_NUM][N_C] [IC_TOTAL-SIDES]) may be used as a modeling parameter, and the local luminance compensation parameter may be a bidirectional reference list index (REFP_NUM) of the current block, three color components (N_C) of the current block, left and bottom of the current block, And three right edge positions (IC_TOTAL-SIDES).

24 illustrates a location of samples used in calculation of a current block, a neighboring block neighboring the current block, and local luminance compensation parameters of the neighboring block according to an embodiment.

According to an embodiment, referring to FIG. 24, a left peripheral block 2420 neighboring to the left of the current block 2410 in a current frame, an upper peripheral block 2430 neighboring to an upper side of the current block 2410, and A block for which local luminance compensation information is available may be determined from the right peripheral block 2440 neighboring the right side of the current block 2410.

According to an embodiment, in determining available blocks, it may be determined whether neighboring blocks are available blocks in a predetermined order according to the size or shape of the current block, and available blocks may be determined among the neighboring blocks. For example, in deriving local luminance compensation information from neighboring blocks, in order to determine whether the neighboring block is an available block, the upper neighboring block 2430 adjacent to the upper side of the current block 2410 is first checked. , A neighboring left peripheral block 2420 on the left side of the current block 2410 may be checked, and a neighboring right peripheral block 2440 on the right side of the current block 2410 may be checked. Further, in deriving the local luminance compensation information from among the neighboring blocks, the right neighboring block 2440 adjacent to the right side of the current block 2410 is first checked, and the upper neighboring block neighboring the upper side of the current block 2410 ( 2430), and finally, the left neighboring block 2420 adjacent to the left side of the current block 2410 may be checked.

According to another embodiment, when the shape of the current block is a rectangular shape having a horizontal length longer than a vertical length, local luminance compensation information may be derived by checking only the upper peripheral block 2430 located above the current block 2410. Can. If the current block has a rectangular shape in which the vertical length is longer than the horizontal length, the local luminance compensation information is checked by checking only one of the left peripheral block 2420 located on the left side of the current block or the right peripheral block 2440 located on the right side. Can be derived.

23 shows an example of the positions of samples used in the calculation of the local luminance compensation parameter of the current block of the current frame.

Referring to FIG. 23, local luminance compensation information of the current block 2310 in the current frame 2300, for example, local luminance compensation parameter is left 2320 except for the upper side of the current block 2310 in the current frame 2300. ), the lower 2330, and the right 2340 edge area samples may be calculated and stored in the memory, and the remaining areas 2350 samples may not be used to calculate local luminance compensation information.

Referring again to FIG. 24, the left peripheral block 2420 neighboring the left side of the current block 2410 includes the lower edge 2421, the left edge 2422, and the right edge, except for the upper edge and the middle portion 2424. The local luminance compensation parameter calculated using the samples at 2423 may be stored in the memory, and the upper peripheral block 2430 adjacent to the upper side of the current block 2410 excludes the upper edge and the middle portion 2434. , Local luminance compensation parameters calculated using samples of the lower edge 2431, the left edge 2432, and the right edge 2433 may be stored in the memory, and the right neighboring the right side of the current block 2440 In the peripheral block 2440, local luminance compensation parameters calculated using samples of the lower edge 2441, the left edge 2244, and the right edge 2443, except for the upper edge and the middle portion 2444, are stored in the memory. It may be. Then, the stored local luminance compensation parameters corresponding to the right edge 2423 and the lower edge 2421 of the left peripheral block 2420 adjacent to the current block 2410, the upper peripheral block adjacent to the current block 2410 ( Stored local luminance compensation parameters corresponding to the lower edge 2431 of 2430, and stored local luminance corresponding to the left edge 2242 and the lower edge 2244 of the right peripheral block 2440 adjacent to the current block 2410. Local luminance compensation information to be applied to the current block 2410 may be derived using at least one of the compensation parameters.

According to an embodiment, the local luminance compensation parameter may be calculated at the 4X4 block level, which is a minimum coding unit, and stored in the memory.

Also, the local luminance compensation parameter may be calculated for each coding unit and stored in the memory. Specifically, the local luminance compensation parameter may be calculated and stored in a single parameter value for one coding unit.

According to an embodiment, the local luminance compensation parameter may be stored in the memory at a 4X4 block level, which is a minimum coding unit.

Also, the local luminance compensation parameter may be stored in the memory in coding units. Specifically, the local luminance compensation parameter may store one parameter value for one coding unit in the memory.

According to an embodiment, the application of the local luminance compensation model may be signaled with a flag of a coding unit level.

According to one embodiment, the scale factor and offset can be derived by searching for a pre-computed and stored value in the frame level parameter map.

According to an embodiment, a local luminance compensation parameter of a position corresponding to a neighboring block neighboring the current block in the parameter storage map may be checked.

According to an embodiment, when the neighboring block neighboring the current block is a block that does not need to apply the local luminance compensation model, for example, when the local luminance compensation model is y = x, the local luminance compensation parameter does not exist. , Local luminance compensation information may be derived by checking the next neighboring block in a predetermined order.

According to an embodiment, when the neighboring block neighboring the current block is a reference index different from the reference index of the current block, the corresponding neighboring block is skipped, and neighboring blocks in the next order are checked to derive local luminance compensation information. . This is because the current block does not need to refer to the luminance change of the neighboring block because the reference index of the current block and the neighboring block are different because they refer to different reference frames.

According to an embodiment, when the neighboring block neighboring the current block is intra prediction, the corresponding neighboring block is skipped, and neighboring blocks in the next order are checked to derive local luminance compensation information.

According to an embodiment, when the current block is a skip mode or a merge mode for acquiring information from neighboring blocks, parameters of a block corresponding to the skip mode or the merge mode may be used. In this case, a flag for local luminance compensation may not be transmitted.

According to one embodiment, even if all neighboring blocks neighboring the current block are checked, if there is no available block providing a valid local luminance compensation parameter set, local luminance compensation may not be applied. Accordingly, the flag signaling bit can be reduced.

25 illustrates local luminance compensation parameters according to another embodiment.

According to another embodiment, in order to obtain a new set of predictive pixels after motion compensation in the absence of an available block providing a set of valid local luminance compensation parameters even though all neighboring blocks neighboring the current block are checked, predictive pixels For the set of default local luminance compensation parameters shown in FIG. 25 can be applied.

Referring to FIG. 25, the default local luminance compensation parameter may include a scale factor (int a[REFP_NUM][N_C]) and an offset (int b[REFP_NUM][N_C]). The scale factor and offset may be distinguished by two bidirectional reference indexes (REFP_NUM) and three color components (N_C).

26 shows another example of a local luminance compensation model using predictive pixels and reconstructed pixels of the current frame.

According to another embodiment, referring to FIG. 26, a prediction sample 2650 of a neighboring block neighboring the current block 2630 of the current frame 2610 and a neighboring neighboring block of the current block 2640 of the current frame 2620 Local luminance compensation information may be derived using the reconstructed sample 2660 of the block. In this case, the prediction sample 2650 of the neighboring block of the current frame 2610 may be a value in which a sample obtained immediately after motion compensation is stored in the memory. Specifically, instead of calculating and storing the local luminance compensation parameter corresponding to the edge of the current coding unit, the prediction frame of the current frame, that is, the prediction samples themselves are stored in memory, and neighboring blocks neighboring the current block of the current frame A local luminance compensation model may be derived using the stored predicted sample and the reconstructed sample of the neighboring block after reconstruction. Accordingly, a temporal dependency on a reference frame can be removed by using a predicted sample and a reconstructed sample of the current frame.

27 shows another example of a modeling process for applying local luminance compensation.

According to another embodiment, referring to FIG. 27, local luminance compensation information may be derived using a prediction sample of a current block of a current frame and a prediction sample of a current block and a DC residual value. For example, prediction pixel values and DC residual values of the entire region of the current block may be used. Alternatively, the predicted pixel value and DC residual value of the current block may be values of pixels located at the edges of the current block (eg, the left, bottom, and top edges of the current block). 27 illustrates a graph in which a local luminance compensation model using DC residual is applied to a prediction sample of a current block. Specifically, when reconstruction of the coding block is completed, the reconstructed sample value of the coding block may be a sum of a predicted sample value, a DC residual value, and an AC residual value. Instead of these reconstructed samples, DC residual values corresponding to the result values obtained by inverse transforming the first coefficient value after the transform for the current frame and the predicted sample values of the current frame are used, without waiting for completion of reconstruction for the coded block. Local luminance compensation information can be derived. Accordingly, instead of treating AC residual value as 0 and losing some accuracy, inverse quantization and inverse transformation are completed and latency caused by failure to process the current block until reconstructed surrounding pixels are available can be reduced. have. However, since the AC residual value itself is not large, the effect of the lost accuracy is not large.

In addition, the temporal dependency on the reference frame may be removed by using only the DC residual value and the prediction sample of the current frame.

According to an embodiment, when the DC residual value is a DCT2 type conversion, the coefficient value located at the upper left of the block may be selected as the DC residual value.

According to another embodiment, when the type of conversion is DCT 8 or DST-7, a coefficient having a phase similar to DC may be selected as the DC residual value.

Referring back to FIG. 27, the local luminance compensation parameter of the local luminance compensation model may be calculated using the predicted sample value and DC residual value of the current block of the current frame and stored in the memory. Therefore, the scale factor of the local luminance compensation parameter of the local luminance compensation model may be determined as 0, and the offset of the local luminance compensation parameter may be determined as a DC residual value.

As illustrated in FIG. 27, according to a local luminance compensation model (scale factor: 0, offset: DC residual value) derived from neighboring blocks neighboring the current block, the DC residual value is assigned to the predicted sample value of the current block. A final prediction sample to which the added value is applied with local luminance compensation can be obtained. In this case, the set of derived local luminance compensation parameters may be divided according to three color components. Also, since only DC residual values are used from neighboring blocks, no calculation is required.

According to another embodiment, instead of deriving by using the predicted sample value and the DC residual value, the DC value (or a value having a phase similar to the DC value) obtained by performing an inverse quantization and inverse transformation process directly compensates for local luminance. Can be set as the offset value of the parameter.

28 shows another example of a local luminance compensation model using the sum of the pixel to be reconstructed of the reference frame and the predicted pixel value and DC residual value of the current frame.

According to another embodiment, referring to FIG. 28, the sum of the prediction sample value and the DC residual value of the neighboring block 2860 neighboring the current block 2840 of the current frame 2820 and the above of the reference frame 2810 Local luminance compensation information may be derived using a reconstructed sample of the neighboring reference block 2850 adjacent to the reference block 2830 indicated by the motion information of the current block 2840 of the current frame 2820. Specifically, instead of storing the local luminance compensation parameter corresponding to the edge of the current coding unit in the memory, the prediction frame of the current frame, that is, the prediction samples themselves are stored in the memory, and neighboring blocks neighboring the current block of the current frame A local luminance compensation model may be derived using the sum of the stored prediction sample and the DC residual value and the reconstructed sample of the reference frame. When the prediction frame of the current frame is stored in the memory, a value obtained by adding a DC residual value to the prediction frame may be stored. In this case, it is not necessary to add the DC residual value again when calculating the local luminance compensation model. Latency can be reduced by using the sum of the predicted sample value and the DC residual value instead of the reconstructed samples of neighboring blocks neighboring the current block of the current frame.

According to an embodiment, parameters for the entire frame are pre-calculated and stored in the memory, and retrieval and use of the stored parameters from neighboring blocks may be applied to other tools. For example, it may be applied to cross component intra prediction (CCIP) or linear model chroma (LMC) using neighboring luma and chroma pixels to generate a model. Specifically, a model for the luma sample of the current block can be used to obtain the chroma sample. Modeling parameters for these models can be calculated at the edge of the coding unit (eg, the left, bottom, and right edges of the coded unit) and stored in memory. In order to derive a parameter to be applied to the current block, stored parameters corresponding to the closest edge of a neighboring coding unit neighboring the current coding unit may be searched.

According to an embodiment, a flag in a frame level or sequence level unit indicating whether a local luminance compensation tool is applied to a current frame or a current sequence may be signaled.

19 and 20 show a block diagram of a video encoding apparatus 1900 according to an embodiment corresponding to each of the video decoding apparatus and video decoding method described above, and a flowchart of a video encoding method according to an embodiment.

19 is a block diagram of a video encoding apparatus 1900 according to an embodiment.

The video encoding apparatus 1900 according to an embodiment may include a memory 1910 and at least one processor 1920 connected to the memory 1910. The operations of the video encoding apparatus 1900 according to an embodiment may operate as individual processors or may be operated under the control of a central processor. Also, the memory 1910 of the video encoding apparatus 1900 may store data received from the outside, data generated by the processor, for example, local luminance compensation information of a neighboring block.

The processor 1920 of the video encoding apparatus 1900 determines an available block among neighboring blocks neighboring the current block in the same frame as the current block, derives local luminance compensation information from the available block, and the local A local luminance compensation model may be determined based on luminance compensation information, and local luminance compensation may be applied using the local luminance compensation model determined for the current block.

Hereinafter, with reference to FIG. 20, the video encoding apparatus 1900 determines an available block among neighboring blocks adjacent to the current block in the same frame as the current block, and local luminance compensation information from the available block Detailed operations for a video encoding method for deriving them, determining a local luminance compensation model based on the local luminance compensation information, and applying local luminance compensation using the determined local luminance compensation model to the current block will be described.

20 is a flowchart of a video encoding method according to an embodiment.

Referring to FIG. 20, in step s2010, the video encoding apparatus 1900, the video decoding apparatus 1700, may determine available blocks among neighboring blocks neighboring the current block in the same frame as the current block.

According to an embodiment, neighboring blocks may be adjacent to at least one of the left, top, top, right, and right sides of the current block.

According to another embodiment, neighboring blocks may be adjacent to at least one of the left side, the top left side, and the top side of the current block.

According to another embodiment, neighboring blocks may be adjacent to at least one of the top, right, and right sides of the current block.

Referring back to FIG. 20, in step s2030, the video encoding apparatus 1900 may derive local luminance compensation information from the available block.

In step s2050, a local luminance compensation model may be determined based on the local luminance compensation information.

In step s2070, local luminance compensation may be applied using the local luminance compensation model determined in the current block. Specifically, a final prediction pixel to which local luminance compensation is applied may be obtained by applying a local luminance compensation model to a sample obtained from motion compensation of a current block.

According to an embodiment, information on application of local luminance compensation is encoded and signaled. Specifically, information about a local luminance compensation parameter stored in a neighboring block adjacent to the current block is encoded and signaled.

So far, we have focused on various embodiments. Those skilled in the art to which the present disclosure pertains will appreciate that the present disclosure may be implemented in a modified form without departing from the essential characteristics of the present disclosure. Therefore, the disclosed embodiments should be considered in terms of explanation, not limitation. The scope of the present disclosure is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be interpreted as being included in the present disclosure.

Meanwhile, the above-described embodiments of the present disclosure can be written in a program executable on a computer, and can be implemented in a general-purpose digital computer that operates a program using a computer-readable recording medium. The computer-readable recording medium includes a storage medium such as a magnetic storage medium (eg, ROM, floppy disk, hard disk, etc.), an optical reading medium (eg, CD-ROM, DVD, etc.).

Claims (15)

Determining an available block among neighboring blocks neighboring the current block in the same frame as the current block;
Deriving local luminance compensation information from the available blocks;
Determining a local luminance compensation model based on the local luminance compensation information; And
And applying local luminance compensation using the determined local luminance compensation model to the current block. According to claim 1,
The neighboring blocks are adjacent to at least one of left, upper left, upper right, upper right, and right sides of the current block. According to claim 2,
The local luminance compensation information includes local luminance compensation parameters corresponding to regions located at each of the left, lower, and right edges of the neighboring blocks. The method of claim 3,
The local luminance compensation parameters are determined and stored based on a predicted sample and a reconstructed sample of regions located at respective edges of the left side, bottom side, and right side of the peripheral block. According to claim 2,
The local luminance compensation information includes local luminance compensation parameters determined using a prediction sample of the neighboring block and a reconstructed sample of the neighboring block,
The prediction sample is a sample stored after motion compensation is performed on the neighboring block, and the video decoding method. The method of claim 3,
The local luminance compensation parameters include predicted sample values of regions located on the left, lower, and right edges of the neighboring block and predicted sample values of regions located on the respective edges of the left, lower, and right sides of the neighboring block. A video decoding method, determined and stored based on a sum of DC residual values. The method of claim 3,
The local luminance compensation parameters are determined and stored based on a prediction sample value of the neighboring block and a sum of a prediction residual value of the neighboring block and a DC residual value. According to claim 2,
The local luminance compensation information includes local luminance compensation parameters determined using a sum of a prediction sample value and a DC residual value of the neighboring block and a reconstructed sample of a neighboring reference block indicated by motion information of the neighboring block,
The predicted sample value is a value stored after motion compensation for the neighboring block is performed. According to claim 2,
The available blocks are determined according to a predetermined order based on the size or shape of the current block. The method of claim 9,
If the neighboring block uses a reference list of an index different from the current block or is intra predicted, it is not determined as the available block. The method of claim 9,
When the current block is a merge mode or a skip mode, local luminance compensation information is derived from a block neighboring a block corresponding to the current block according to the merge mode or skip mode. According to claim 2,
If the available block does not exist among the neighboring blocks,
A video decoding method in which local luminance compensation is not applied. According to claim 2,
If the available block does not exist among the neighboring blocks,
The local luminance compensation information includes default local luminance compensation parameters,
And applying local luminance compensation to the current block using the default luminance compensation parameter. Determining an available block among neighboring blocks neighboring the current block in the same frame as the current block;
Deriving local luminance compensation information from the available blocks;
Determining a local luminance compensation model based on the local luminance compensation information; And
And applying local luminance compensation using the determined local luminance compensation model to the current block. Memory; And
And at least one processor connected to the memory,
The at least one processor is:
Determine an available block among neighboring blocks neighboring the current block in the same frame as the current block,
Derive local luminance compensation information from the available block, determine a local luminance compensation model based on the local luminance compensation information,
A video decoding apparatus applying local luminance compensation using the determined local luminance compensation model to the current block.

Images