KR20200066638A - Image encoding method and apparatus, Image decoding method and apparatus - Google Patents

Abstract

Obtain information about a transform coefficient of a current block from a bitstream, determine a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block, and a size of the current block, and use the determined filter To obtain a prediction block of the current block including the prediction sample of the current sample, and obtain a residual block of the current block based on information on the obtained transform coefficients of the current block, the prediction block of the current block, and the current An image decoding method for restoring a current block based on a residual block of a block is disclosed.

Description

Image encoding method and apparatus, Image decoding method and apparatus

The method and apparatus according to an embodiment may encode or decode an image using various types of coding units included in the image. A method and apparatus according to an embodiment includes an intra prediction method and apparatus.

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-definition 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, an efficient image compression method has been implemented through a process of processing an image to be encoded by an arbitrary method.

Various data units may be used to compress an image, and an inclusion relationship may exist between these data units. In order to determine the size of a data unit used for such image compression, data units may be divided by various methods, and an optimized data unit may be determined according to characteristics of the image, thereby encoding or decoding an image.

An image decoding method according to an embodiment may include obtaining information about a transform coefficient of a current block from a bitstream; Determining a filter used for the current sample based on at least one of a distance between a current sample in a current block and a reference sample, and a size of the current block; Obtaining a prediction block of a current block including a prediction sample of the current sample generated using the determined filter; Obtaining a residual block of the current block based on the information on the transform coefficient of the obtained current block; And restoring the current block based on the prediction block of the current block and the residual block of the current block.

Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block includes: a distance between the current sample and the reference sample in the current block and the current And determining a type of a filter used in the current sample and a coefficient of the filter based on at least one of block sizes.

The filter type is a low pass filter, a Gaussian filter, a bilateral filter, a uniform filter, a bilinear interpolation filter, and a cubic filter ( cubic filter) and DCT (Discrete Cosign Transform) filter (DCT filter).

The number of taps of the filter used for the current sample may be a predetermined value, or may be determined based on at least one of a distance between the current sample and the reference sample and the size of the current block. The predetermined value may be an integer of 4 or more.

Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block includes: a size of the current block and a sample and a reference sample in the current block Determining a plurality of filters for the current block based on at least one of the distances between them; And determining a filter corresponding to the current sample among a plurality of filters for the current block.

Determining a plurality of filters for the current block based on at least one of a size of the current block and a distance between a sample in the current block and a reference sample includes: a height or width of the current block and a sample in the current block. And determining a plurality of filters for the current block based on a ratio of distances between reference samples.

Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block includes: in the current block based on the intra prediction mode of the current block. Determining a first reference sample corresponding to the sample; Determining a plurality of filters for the current block based on a distance between the sample and a first reference sample; And determining a filter corresponding to the current sample among a plurality of filters for the current block.

Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block, based on the size of the current block, is used for the current block Determining a number of filters, and determining a filter for the current block corresponding to the number of filters; And determining a filter used for the current sample among filters for the current block based on at least one of a distance between the current sample and a reference sample and the size of the current block.

Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block includes: an intra prediction mode of the current block and a shape of the current block ( and determining a filter used for the current sample based on at least one of shapes.

Determining a filter used for the current sample based on at least one of an intra prediction mode of the current block and a shape of the current block,

If the intra prediction mode of the current block is a predetermined intra prediction mode, determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block. It may include.

Determining a filter used for the current sample based on the intra prediction mode of the current block and the shape and at least one of the current block,

When the width of the current block is less than or equal to a predetermined first value, and the height of the current block is less than or equal to a predetermined second value, the distance between the current sample and the reference sample in the current block and the size of the current block And determining a filter used for the current sample based on at least one of the above.

Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block, the distance between the current sample and the reference sample is less than a predetermined value. And determining a first filter for the current sample, and determining a second filter for the current sample if the distance between the current sample and the reference sample is greater than a predetermined value. The smoothing strength of may be smaller than that of the second filter.

An image encoding method according to an embodiment may include determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in a current block and a size of the current block; Generating a prediction block of a current block including a prediction sample of the current sample generated using the determined filter; And encoding information on transform coefficients of the current block based on the prediction block of the current block.

The image decoding apparatus according to an embodiment obtains information about a transform coefficient of a current block from a bitstream, and based on at least one of a distance between a current sample and a reference sample in a current block and a size of the current block. Determine a filter to be used, obtain a prediction block of a current block including a prediction sample of the current sample generated using the determined filter, and obtain the prediction block of the current block based on information about the transform coefficient of the obtained current block And a processor that obtains a residual block of and reconstructs the current block based on a prediction block of the current block and a residual block of the current block.

A computer program for an image decoding method according to an embodiment of the present disclosure may be recorded on a computer-readable recording medium.

1A is a block diagram of an image decoding apparatus according to various embodiments.
1B is a flowchart of an image decoding method according to various embodiments.
1C is a block diagram of an image decoder according to various embodiments.
1D is a block diagram of an image decoding apparatus according to various embodiments.
2A is a block diagram of an image encoding apparatus according to various embodiments.
2B is a flowchart of an image encoding method according to various embodiments.
2C is a block diagram of an image decoder according to various embodiments.
2D is a block diagram of an image encoding apparatus according to various embodiments.
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 illustrates 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.
8 illustrates 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 for 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.
FIG. 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 four coding units in a square shape according to an embodiment.
12 illustrates that a processing order between 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 illustrating a depth and a index (part index, PID) for classifying coding units, which may be determined according to types and sizes 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 diagram illustrating intra prediction modes according to an embodiment.
18 illustrates a method of generating a prediction sample of a current sample using a different filter based on at least one of a distance between a current sample and a reference sample and a size of a current block, according to an embodiment of the present disclosure It is a figure for illustration.
FIG. 19 shows a right or upper reference line according to a coding order flag, in which a coding order between coding units is determined in a forward or reverse direction, and a determined coding code order is determined according to an embodiment of the present disclosure. This is a diagram for explaining that it can be used for intra prediction.

Best mode for carrying out the invention

A video decoding method according to various embodiments may include obtaining information about a transform coefficient of a current block from a bitstream; Determining a filter used for the current sample based on at least one of a distance between a current sample in a current block and a reference sample, and a size of the current block; Obtaining a prediction block of a current block including a prediction sample of the current sample generated using the determined filter; Obtaining a residual block of the current block based on the information on the transform coefficient of the obtained current block; And restoring the current block based on the prediction block of the current block and the residual block of the current block.

The video encoding method according to various embodiments may include determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in a current block and a size of the current block; Generating a prediction block of a current block including a prediction sample of the current sample generated using the determined filter; And encoding information on transform coefficients of the current block based on the prediction block of the current block.

The video decoding apparatus according to various embodiments obtains information about a transform coefficient of a current block from a bitstream, and based on at least one of a distance between a current sample and a reference sample in a current block and a size of the current block. Determine a filter to be used, obtain a prediction block of a current block including a prediction sample of the current sample generated using the determined filter, and obtain the prediction block of the current block based on information about the transform coefficient of the obtained current block And a processor that obtains a residual block of and reconstructs the current block based on a prediction block of the current block and a residual block of the current block.

A computer-readable recording medium in which a program for implementing a method according to various embodiments is recorded may be included.

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 part of the specification "includes" a certain component, this means that other components may be further included instead of excluding other components, unless specifically stated to the contrary.

In addition, the term "part" as 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 the 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 microprocessor, a combination of multiple 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 It may also 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 19. A method of determining a data unit of an image according to an embodiment is described with reference to FIGS. 3 to 16, and a distance and a current to a reference sample according to an embodiment with reference to FIGS. 1-2 and 17 to 19 An image encoding or decoding method and apparatus for determining a filter based on at least one of block sizes and performing intra prediction adaptively using the determined filter is described.

Hereinafter, an image encoding/decoding method and apparatus for adaptively performing intra prediction 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.

1A is a block diagram of an image decoding apparatus according to various embodiments.

The image decoding apparatus 100 according to various embodiments may include an acquisition unit 105, an intra prediction unit 110, and an image decoding unit 115.

The acquisition unit 105, the intra prediction unit 110, and the image decoding unit 115 may include at least one processor. Also, the acquisition unit 105, the intra prediction unit 110, and the image decoding unit 115 may include a memory that stores instructions to be executed by at least one processor. The image decoding unit 115 may be implemented in hardware separate from the acquisition unit 105 and the intra prediction unit 110, or may include the acquisition unit 105 and the intra prediction unit 110.

The acquiring unit 105 may acquire information about a transform coefficient of a current block from a bitstream. The acquisition unit 105 may obtain information about a prediction mode of a current block and information about an intra prediction mode of a current block from a bitstream.

The acquisition unit 105 may include information indicating an intra mode or an inter prediction mode as information about a prediction mode of the current block. The information on the intra prediction mode of the current block may be information on the intra prediction mode applied to the current block among the plurality of intra prediction modes. For example, the intra prediction mode may be one of a DC mode, a planar mode, and at least one angular mode having a prediction direction. The angular mode includes a horizontal mode, a vertical mode, and a diagonal mode, and may include a mode having a predetermined direction except for a horizontal direction, a vertical direction, and a diagonal direction. For example, the number of angular modes may be 65 or 33.

The intra prediction unit 110 may be activated when the prediction mode of the current block is an intra prediction mode.

The intra prediction unit 110 may perform intra prediction on the current block based on the intra prediction mode of the current block. The intra prediction unit 110 determines a reference sample for the current sample among reference samples based on the location of the current sample in the current block and the intra prediction mode of the current block, and uses the reference sample for the current sample to determine the current sample. Predictive sample values can be generated. In this case, the reference sample may include a sample of the left or upper reference line adjacent to the current block. The reference sample for the current sample may include at least one neighboring sample of the current block among samples of a reference line on the left or upper side of the current block. If there is only one reference sample for the current sample, the intra prediction unit 110 may generate the predicted sample value of the current sample using the reference sample. Meanwhile, when there are two or more reference samples for the current sample, the intra prediction unit 110 may generate a prediction sample of the current sample by applying a filter to the sample values of the two or more reference samples for the current sample. At this time, the coefficient of the filter may be an integer. In order to determine the coefficient of the filter as an integer, scaling on the coefficient of the filter is performed and the coefficient of the scaled filter can be used. When scaling is performed on the coefficients of the filter and the coefficients of the scaled filter are used, a process of descaling inversely, as long as the coefficients of the filter are scaled, may be performed later. The accuracy of the filter may be an accuracy of 1/32 fractional pixels.

The intra prediction unit 110 may determine a filter used for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample. The intra prediction unit 110 determines at least one filter candidate that can be applied to the current sample, and based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block, the current one of the at least one filter candidate The filter used for the sample can be determined. In this case, the distance between the current sample and the reference sample may be the distance between the current sample and the reference sample located in the vertical direction of the current sample or the distance between the current sample and the reference sample located in the horizontal direction of the current sample, in this case, the current sample The distance from and the reference sample may correspond to the position coordinate value of the current sample in the current block. Therefore, it can be seen that the intra prediction unit 110 determines a filter used for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample.

The intra prediction unit 110 may determine the type of filter and coefficient of the filter used for the current sample based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block. At this time, the type of filter is a low pass filter, a Gaussian filter, a bilateral filter, a uniform filter, a bilinear interpolation filter, and a cubic filter. (cubic filter), [1 2 1] filter, and DCT (Discrete Cosign Transform) filter (DCT filter). At this time, the DCT filter may be a 4-tap DCT interpolation filter (DCT interpolation filter) used for compensating sub-pixel motion of a chroma component. Also, a new filter may be generated by combining two or more filters, and the newly generated filter may be added as a filter type. In addition, the types of filters listed above are not limited, and various types of filters may be types of filters used in the current sample.

The number of taps of the filter used for the current sample may be a predetermined value. At this time, the predetermined value may be 4. That is, the filter used for the current sample may be a 4-tap filter. However, the present invention is not limited thereto, and the predetermined value may be one of various integer values of 1 or more, preferably 2 or more.

Alternatively, the number of taps of the filter used for the current sample may be determined based on at least one of the distance between the current sample and the reference sample and the size of the current block. For example, if the distance between the current sample and the reference sample is less than a predetermined value, the intra prediction unit 110 may determine the number of taps of the filter as a predetermined first tap number. If the distance between the current sample and the reference sample is greater than a predetermined value, the intra prediction unit 110 may determine the number of taps of the filter as a predetermined second tap number. At this time, the predetermined number of first taps may be smaller than the predetermined number of second taps.

The intra prediction unit 110 may determine a plurality of filters for the current block based on at least one of a size of a current block and a distance between at least one sample and a reference sample in the current block. That is, the plurality of filters for the current block may include at least one filter candidate that can be used for the current sample.

The intra prediction unit 110 may determine a filter corresponding to the current sample among a plurality of filters for the current block. At this time, the intra prediction unit 110 is based on the size (height or width) of the current block, the ratio of the distance between at least one sample in the current block, and the position of the current sample in the current block (or the distance between the current sample and the reference sample). Accordingly, a filter corresponding to the current sample among the plurality of filters for the current block may be determined.

The intra prediction unit 110 may determine a first reference sample corresponding to a sample in the current block based on the intra prediction mode of the current block. For example, the intra prediction unit 110 may determine, as a first reference sample, a reference sample intersecting an extension line of the intra prediction direction according to the intra prediction mode of the current block from the current sample among the reference samples. The intra prediction unit 110 may determine a plurality of filters for the current block based on the distance between the sample and the first reference sample. The intra prediction unit 110 may determine a filter corresponding to the current sample among a plurality of filters for the current block.

The intra prediction unit 110 may determine the number of filters used for the current block based on the size of the current block, and determine a filter for the current block corresponding to the number of filters. For example, when the height or width of the current block is smaller than a predetermined value, the video decoding apparatus 100 may determine the number of filters used for the current block to be one. If the number of filters used for the current block is determined to be one, the intra prediction unit 110 may determine a filter for the current block based on the size of the current block and the current intra prediction mode. That is, the intra prediction unit 110 determines the threshold value based on the size of the current block, and determines the intra prediction mode index difference value based on the index difference value between the current intra prediction mode and the vertical mode and horizontal mode, and The filter for the current block may be determined by comparing the determined intra prediction mode index difference value with a threshold value.

Alternatively, if the index value of the intra prediction mode of the current block is an odd value, the intra prediction unit 110 may determine the first filter as a filter for the current block, and when the value of the intra prediction mode of the current block is an even value , A second filter may be determined as a filter for the current block.

The intra prediction unit 110 may determine a range of a distance between a sample to which each filter is applied and a reference sample based on the size of the current block. For example, if the height and width of the current block are both greater than or equal to 32, the distance between the sample of the current block where filter f0 is used and the reference sample is [0, 2), and the sample of the current block where filter f1 is used. The distance between the reference sample is [2, 4), the distance between the sample of the current block using filter f2 and the reference sample is [4,8), and the distance between the sample of the current block using filter f3 and the reference sample is [8,16] ), and a distance between a sample of a current block in which filter f4 is used and a reference sample may be (16, size). Otherwise (if the height of the current block is less than 32 or the width is less than 32), the distance between the sample of the current block where filter f0 is used and the reference sample is [0,1), and the current block where filter f1 is used. The distance between the sample and the reference sample is [1, 2), the distance between the sample of the current block using filter f2 and the reference sample is [2,3), and the distance between the sample of the current block using filter f3 and the reference sample is [3 ,4), and the distance between the sample of the current block and the reference sample in which the filter f4 is used may be [4, size).

The intra prediction unit 110 may determine a filter used for the current sample among filters for the current block based on at least one of the distance between the current sample and the reference sample and the size of the current block.

The intra prediction unit 110 may determine a filter used for the current sample based on at least one of an intra prediction mode of the current block and a shape of the current block.

For example, when the intra prediction mode of the current block is a predetermined intra prediction mode, the intra prediction unit 110 may transmit the current sample to the current sample based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block. The filter used can be determined. At this time, the predetermined intra prediction mode may be one of an angular mode except for the DC mode and the planar mode. Specifically, the predetermined intra prediction mode may be one of the remaining modes excluding diagonal modes among angular modes.

For example, if the prediction mode of the current block is a horizontal mode or a vertical mode, the intra prediction unit 110 may use a filter (eg, an interpolation filter or [1] to reference samples to generate prediction samples of the current block). , 2, 1] Intra prediction can be performed without using a reference sample filter, etc.). When the prediction mode of the current block is a diagonal mode having an angle of a multiple of 45 degrees, the intra prediction unit 110 performs intra prediction using the [1, 2, 1] reference sample filter to generate prediction samples of the current block. It can be done. The intra prediction unit 110 is a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block when the prediction mode of the current block is an angular mode other than the above modes Can decide.

The intra prediction unit 110 further filters a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block based on whether the current block is square or rectangular. Can decide.

Alternatively, the intra prediction unit 110 further determines a filter used for the current sample based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block based on the ratio of the height and width of the current block. Can be.

If the width of the current block is less than or equal to a predetermined first value, and the height of the current block is less than or equal to a predetermined second value, the intra prediction unit 110 may include a distance between the current sample and the reference sample in the current block and the current The first filter used for the current sample may be determined based on at least one of the block sizes. In addition, if the width of the current block is greater than a predetermined first value or the height of the current block is greater than a predetermined second value, the intra prediction unit 110 may determine the distance between the current sample and the reference sample in the current block and the current block. A second filter used for the current sample may be determined based on at least one of the sizes of.

If the distance between the current sample and the reference sample is less than a predetermined value, the intra prediction unit 110 determines a first filter for the current sample, and when the distance between the current sample and the reference sample is greater than a predetermined value, the current sample A second filter for can be determined. At this time, the smoothing strength of the first filter may be smaller than the smoothing strength of the second filter.

The intra prediction unit 110 may obtain a prediction block of a current block including a prediction sample of the current sample generated using the determined filter.

The image decoder 115 may obtain a residual block of the current block based on information about the transform coefficient of the current block. That is, the image decoder 115 may obtain a residual sample of the residual block of the current block by performing inverse quantization and inverse transformation based on information on the transform coefficient of the current block from the bitstream.

The image decoder 115 may reconstruct the current block based on the prediction block of the current block and the residual block of the current block. The image decoder 115 generates a reconstructed sample in the current block using the sample value of the predicted sample in the predicted block of the current block and the sample value of the residual sample in the residual block of the current block, and based on the reconstructed sample It is possible to create a reconstructed block of blocks.

On the other hand, the image decoding apparatus 100 determines the filter used for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample, and displays flag information indicating whether to perform adaptive intra prediction. It is possible to determine whether to obtain a filter used for a current sample based on at least one of a size of a current block and a distance between a current sample and a reference sample based on flag information. In this case, the flag information may be obtained for each block, and particularly, for each largest coding unit. Or, it may be obtained for each frame.

Also, the image decoding apparatus 100 may obtain flag information commonly applied to luminance components and color difference components. Alternatively, the image decoding apparatus 100 may obtain flag information applied to luminance components or color difference components, respectively.

The image decoding apparatus 100 may determine a filter set commonly applied to luminance components and color difference components. Alternatively, the image decoding apparatus 100 may determine a filter set applied for each component.

Alternatively, the image decoding apparatus 100 may determine whether to determine a filter used for the current sample based on at least one of a size of a current block and a distance between a current sample and a reference sample, without obtaining flag information from the bitstream Can be. For example, when the prediction mode of the current block is a predetermined intra prediction mode, the image decoding apparatus 100 may use a filter used for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample It can be determined that intra prediction is performed adaptively by determining.

Alternatively, the image decoding apparatus 100 may determine whether to perform intra prediction adaptively based on the weights of the filtering reference sample and the filter using information of neighboring blocks, without obtaining flag information from the bitstream. For example, the image decoding apparatus 100 filters a filter used for the first sample in the neighboring block based on the size of the neighboring block and the distance between the first sample and the reference sample in the neighboring block for the neighboring block of the current block. Determine, at least one of a size of at least one current block and a distance between a current sample and a reference sample according to flag information of a neighboring block indicating whether to perform intra prediction adaptively based on a filter used for the first sample in the neighboring block It is possible to determine whether to determine the filter used for the current sample based on one. Alternatively, when the size of the current block is a predetermined first block size, the image decoding apparatus 100 determines a filter used for the current sample based on at least one of the size of the current block and the distance between the current sample and the reference sample And, intra prediction may be performed based on a filter used for the current sample. In the case of a predetermined second block size, the image decoding apparatus 100 may perform conventional intra prediction without determining a filter used for the current sample based on the size of the current block and the distance between the current sample and the reference sample. have.

The image decoding apparatus 100 determines a filter used for the current sample based on at least one of a size of a current block and a distance between a current sample and a reference sample, and a sub prediction unit based on the filter used for the current sample. Intra prediction can be performed by combining intra-prediction sub/decoding tools similar to a decoding tool. Alternatively, the image decoding apparatus 100 may give priority between sub/decoding tools of a plurality of intra predictions and perform intra prediction according to the priority between sub/decoding tools. That is, when a sub/decoding tool having a high priority is used, a sub/decoding tool having a low priority may not be used, and when a sub/decoding tool having a high priority is not used, a low priority is set. The having/decoding tool can be used.

1B is a flowchart of an image decoding method according to various embodiments.

In step S105, the image decoding apparatus 100 may obtain information about a transform coefficient of the current block from the bitstream.

In operation S110, the image decoding apparatus 100 may determine a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block.

In operation S115, the image decoding apparatus 100 may obtain a prediction block of the current block including the prediction sample of the current sample generated using the determined filter.

In operation S120, the image decoding apparatus 100 may obtain a residual block of the current block based on information on the transform coefficient of the current block.

In operation S125, the image decoding apparatus 100 may reconstruct the current block based on the prediction block and residual block of the current block.

1C is a block diagram of an image decoder 6000 according to various embodiments.

The image decoding unit 6000 according to various embodiments performs operations that are performed by the image decoding unit 115 of the image decoding apparatus 100 to encode image data.

Referring to FIG. 1C, the entropy decoding unit 6150 parses encoded image data to be decoded and encoding information necessary for decoding from the bitstream 6050. The coded image data is a quantized transform coefficient, and the inverse quantization unit 6200 and the inverse transform unit 6250 recover residual data from the quantized transform coefficients.

The intra prediction unit 6400 performs intra prediction for each block. The intra prediction unit 6400 of FIG. 1C may correspond to the intra prediction unit 110 of FIG. 1A.

The inter prediction unit 6350 performs inter prediction by using a reference image obtained from the reconstructed picture buffer 6300 for each block. By adding prediction data and residual data for each block generated by the intra prediction unit 6400 or the inter prediction unit 6350, data in a spatial region for a block of the current image is restored, and the deblocking unit 6450 and The SAO performing unit 6500 may output a filtered reconstructed image 6600 by performing loop filtering on the reconstructed spatial region data. Also, reconstructed images stored in the reconstructed picture buffer 6300 may be output as reference images.

In order to decode image data in a decoding unit (not shown) of the image decoding apparatus 100, step-by-step operations of the image decoding unit 6000 according to various embodiments may be performed block by block.

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

The image decoding apparatus 100 according to an embodiment may include a memory 120 and at least one processor 125 connected to the memory 120. The operations of the image decoding apparatus 100 according to an embodiment may operate as individual processors or may be operated under the control of a central processor. Also, the memory 120 of the video decoding apparatus 100 may store data received from the outside and data generated by the processor. The processor 125 of the image decoding apparatus 100 obtains information about a current block from a bitstream, and is used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block A filter is determined, a prediction block of a current block including a prediction sample of a current sample generated using the determined filter is obtained, and a residual block of the current block is obtained based on information about transform coefficients of the current block. , The current block may be reconstructed based on the prediction block and residual block of the current block.

2A is a block diagram of an image encoding apparatus according to various embodiments.

The image encoding apparatus 150 according to various embodiments may include an intra prediction unit 155 and an image encoding unit 160.

The intra prediction unit 155 and the image encoding unit 160 may include at least one processor. Also, the intra prediction unit 155 and the image encoding unit 160 may include a memory storing instructions to be executed by at least one processor. The intra prediction unit 155 and the image encoding unit 160 may be implemented in separate hardware, or may include an intra prediction unit 155 and the image encoding unit 160.

The intra prediction unit 155 may determine a filter used for the current sample based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block.

The intra prediction unit 155 may generate a prediction block of a current block including a prediction sample of the current sample generated using a filter used for the current sample.

The intra prediction unit 155 may determine a filter type and a filter coefficient used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block.

The number of taps of the filter used for the current sample may be a predetermined value. At this time, the predetermined value may be an integer of 4 or more. Alternatively, the number of taps of the filter used for the current sample may be determined based on at least one of the distance between the current sample and the reference sample and the size of the current block.

The intra prediction unit 155 may determine a plurality of filters for the current block based on at least one of a size of a current block and a distance between a sample in a current block and a reference sample.

The intra prediction unit 155 may determine a filter corresponding to the current sample among a plurality of filters for the current block.

The intra prediction unit 155 may determine a first reference sample corresponding to a sample in the current block based on the intra prediction mode of the current block. The intra prediction unit 155 may determine a plurality of filters for the current block based on the distance between the sample in the current block and the first reference sample. The intra prediction unit 155 may determine a filter corresponding to the current sample among a plurality of filters for the current block.

The intra prediction unit 155 determines the number of filters used in the current block based on the size of the current block, determines the filter for the current block corresponding to the number of filters, and the intra prediction unit 155 determines the current sample The filter used for the current sample among filters for the current block may be determined based on at least one of the distance between the reference samples and the size of the current block.

When the intra prediction mode of the current block is a predetermined intra prediction mode, the intra prediction unit 155 filters a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block. Can decide.

If the distance between the current sample and the reference sample is less than a predetermined value, the intra prediction unit 155 determines a first filter for the current sample, and when the distance between the current sample and the reference sample is greater than a predetermined value, the current sample A second filter for can be determined. At this time, the smoothing strength of the first filter may be smaller than the smoothing strength of the second filter.

The image encoder 160 may encode information about a transform coefficient of the current block based on the prediction block of the current block. That is, the image encoder 160 generates the residual block of the current block based on the original block of the current block and the prediction block of the current block, and transforms and quantizes the residual block of the current block to the transform coefficient of the current block. Information about can be encoded. The image encoder 160 may encode information about a prediction mode of the current block and information about an intra prediction mode of the current block.

The image encoder 160 may generate a bitstream including information on transform coefficients of the current block and output a bitstream.

2B is a flowchart of an image encoding method according to various embodiments.

In operation S150, the image encoding apparatus 150 may determine a filter used for the current sample based on at least one of a distance between a current sample and a reference sample and a size of the current block.

In operation S155, the video encoding apparatus 150 may generate a prediction block of the current block including the prediction sample of the current sample generated using the determined filter. In operation S160, the image encoding apparatus 150 may encode information on transform coefficients of the current block based on the prediction block of the current block.

2C is a block diagram of an image encoder according to various embodiments.

The image encoding unit 7000 according to various embodiments performs operations that are performed by the image encoding unit 160 of the image encoding apparatus 150 to encode image data.

That is, the intra prediction unit 7200 performs intra prediction for each block among the current images 7050, and the inter prediction unit 7150 performs reference images obtained from the current image 7050 and the reconstructed picture buffer 7100 for each block. To perform inter prediction.

Residue data is generated by subtracting prediction data for each block output from the intra prediction unit 7200 or the inter prediction unit 7150 from data for an encoded block of the current image 7050, and converting unit 7250 And the quantization unit 7300 may perform transform and quantization on the residual data to output quantized transform coefficients for each block. The intra predictor 7200 of FIG. 2C corresponds to the intra predictor 155 of FIG. 2A Can be.

The inverse quantization unit 7450 and the inverse transform unit 7500 may perform inverse quantization and inverse transformation on the quantized transform coefficients to restore residual data in the spatial domain. The residual data of the reconstructed spatial region is restored to the data of the spatial region for the block of the current image 7050 by adding it with the prediction data for each block output from the intra prediction unit 7200 or the inter prediction unit 7150. . The deblocking unit 7550 and the SAO performing unit perform in-loop filtering on the data of the reconstructed spatial region to generate a filtered reconstructed image. The generated reconstructed image is stored in the reconstructed picture buffer 7100. The reconstructed images stored in the reconstructed picture buffer 7100 may be used as reference images for inter prediction of other images. The entropy encoding unit 7350 entropy-encodes the quantized transform coefficients, and the entropy-encoded coefficients may be output to the bitstream 7400.

In order for the image encoder 7000 according to various embodiments to be applied to the image encoding apparatus 150, step-by-step operations of the image encoder 7000 according to various embodiments may be performed block by block.

2D is a block diagram of an image encoding apparatus 150 according to an embodiment.

The video encoding apparatus 150 according to an embodiment may include a memory 165 and at least one processor 170 connected to the memory 165. The operations of the image encoding apparatus 150 according to an embodiment may operate as individual processors or may be operated under the control of a central processor. Further, the memory 165 of the video encoding apparatus 150 may store data received from the outside and data generated by the processor.

The processor 170 of the image encoding apparatus 150 determines a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block, and generates using the determined filter The prediction block of the current block including the prediction sample of the current sample may be generated, and information on the transform coefficient of the current block may be encoded based on the prediction block of the current block.

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 coding tree units (CTUs). 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), a maximum coding unit (CTU) is a maximum coding block of a luma sample and two maximum 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 largest 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 that is coded by a color plane separated for each color component, a coding unit is a unit including syntax structures used to code a corresponding picture and samples of a picture.

As described above, the maximum coding block and the maximum coding unit are concepts that are distinct 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 Is mentioned 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 the 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 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 size of a luma block can 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 a maximum size of a bi-dividable luma coding block obtained from a bitstream and information about a difference in a luma block size are combined, a size of a 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 splitting in an I slice may be 32x32, and a maximum size of a luma coding block capable of ternary splitting in a P slice or 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 quad-segmented (QUAD_SPLIT) or not.

If the current coding unit is quadrant or not, information indicating whether to split the current 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.

When 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. A binstring is a binary representation of information. The binstring may consist of at least one bit. The image decoding apparatus 100 may obtain division type mode information corresponding to the empty string based on the division 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 to this, 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. In addition, 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 division is currently 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 image 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 square and 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 (i.e., 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 a 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. Also, 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. In addition, the video decoding apparatus 100 may determine the size of the coding unit based on at least one of a width, a height, or a width 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 the coding unit indicated by the 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 150 may determine the pre-promised split mode mode information based on the 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 largest 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 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, to vertically, horizontally, or to divide 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. The coding unit 310a having the or may not be split, or the split coding units 310b, 310c, 310d, 310e, 310f, etc. may be determined based on split mode mode information indicating a predetermined splitting method.

Referring to FIG. 3, the video 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 image 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 mode 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. The 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 video decoding apparatus 100 may determine whether to split the current coding unit of the non-square or not according to the split mode mode information in a predetermined method. Referring to FIG. 4, when the block shape information of the current coding unit 400 or 450 represents a non-square shape, the image decoding apparatus 100 according to split mode mode information indicating that the splitting mode mode information 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 split and 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 may display a 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 shape of the current coding unit 400 or 450 By determining a plurality of coding units.

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 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 block shape information may be horizontal because the length of the width is longer than the length of the height. When the ratio of width and height is 1:4, the length of the width is shorter than the length of the height, so the block shape information may be vertical. 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 a 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, the coding units 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 further split 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 splits 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 having a square shape is not divided into coding units or split 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 above-described features.

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 video 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 shape 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 split 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, a coding unit of a square may be determined from a coding unit of a non-square shape, and a coding unit of a square shape may be recursively divided to determine a coding unit of a non-square shape.

Referring to FIG. 5, a predetermined coding unit (for example, located in the center) among odd numbered third coding units 520b, 520c, and 520d determined by dividing and determining the second coding unit 510 in a non-square shape A coding unit or a square type coding unit) 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 having 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 odd numbered 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 no longer being divided or is divided into a configurable 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 partitioning form (for example, only divided into 4 coding units or the second coding unit 510 is divided into a form corresponding to the divided form), or a predetermined 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 center 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 is 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 position 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 (eg, 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) can be included. The image decoding apparatus 100 may obtain split mode mode information obtained from a predetermined location 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 in order 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, so that the middle coding unit 620b or the middle coding unit (660b) can be determined. For example, the image decoding apparatus 100 determines the position 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 positions 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 are within the 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 at 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 includes (xb, yb) which is the coordinates of the sample 630b located in the center. 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 information indicating the relative position of the sample 630b in the upper left of the middle coding unit 620b, and the relative position of the sample 630c in 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 position 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 in a way.

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 coding units 620b having different sizes among coding units 620a, 620b, and 620c.

According to an embodiment, the image decoding apparatus 100 may include (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. 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 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 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 by 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 (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 and 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 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 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 by 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 location 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 corresponding 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 a position 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 is omitted.

According to an embodiment, when the current coding unit in 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 image decoding apparatus 100 may determine a coding unit 620b positioned in the center in consideration of a location where the 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 kinds 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) 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. Of the coding units 620a, 620b, and 620c, a coding unit 620b including a sample from 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 can be interpreted as samples at an arbitrary 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 a current coding unit has a square shape or a non-square shape, 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. As 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 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 the coding unit, and the image decoding apparatus 100 may include 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 split recursively 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 thereof 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 in 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. To determine the second coding units 730a and 730b by dividing them in the horizontal direction, or to determine the second coding units 750a, 750b, 750c and 750d 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 an 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 first coding unit 700 is divided into vertical and horizontal directions, the image decoding apparatus 100 processes the second coding units 750a, 750b, 750c, and 750d determined in one row, and then processes the coding units. It may be determined according to a predetermined order (for example, a raster scan order or a z scan order 750e) in which coding units positioned in a next row are processed.

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 coding units 710a, 710b, 730a, 730b, 750a, 750b, 750c, and 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, respectively, 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 side 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 the processing order is determined according to coding units before division, respectively, the coding units should not be interpreted to be limited to the above-described embodiment, and coding units determined by being divided into various types are determined. 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 image 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 boundaries 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 sequence 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 descriptions 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 (not shown). 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 a 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 information indicates that the first coding unit 900 is split in the horizontal direction or the 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, wherein 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. In addition, since the boundaries of the second coding units 920a, 920b, and 920c determined by dividing the square first coding unit 900 in the horizontal direction cannot 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 descriptions 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 a case in which a second coding unit having 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 a receiver (not shown). , 1010b, 1020a, 1020b). The second coding units 1010a, 1010b, 1020a, and 1020b may be divided independently. Accordingly, the image decoding apparatus 100 may determine whether to divide or not divide 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 in 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 left second coding unit 1010a is split in the horizontal direction, the image decoding apparatus 100 may have the right second coding unit 1010b in 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 the second coding unit 1020a or 1020b in the non-square shape determined by dividing the first coding unit 1000 in the horizontal direction in the vertical direction, and then the third coding unit. (1022a, 1022b, 1024a, 1024b) can be determined. However, when the image 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.

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 split 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 divide 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 side in the horizontal direction, and the second coding unit 1110b on the right side. The third coding units 1114a and 1114b in 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 a 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 between 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 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 respectively split in the horizontal direction, and the third coding units 1226a, 1226b, and 1226c. , 1226d). Since the splitting process of the second coding units 1210a, 1210b, 1220a, and 1220b has been 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. 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 square coding units (1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 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 a 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 in the horizontal direction, respectively. 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 a procedure 1217 for 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 third coding units 1220b in the lower second coding unit 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 each divided to determine a third coding unit 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d. 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 coding units recursively through different processes based on 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 from each other. 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 depth of the current coding unit is greater than the depth 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 video decoding apparatus 100 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 divided 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 is non-square, or'indicating that a width is a non-square longer than the 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 a 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/2xN 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 (for example, 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 image 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 a horizontal direction, thereby forming a third coding unit 1304 having an N/2xN/2 size or a third coding unit 1304 having an N/2xN/4 size. ) Or split in the vertical direction and the horizontal direction to determine the third coding unit 1314 of size N/4xN/2.

According to an embodiment, the image decoding apparatus 100 divides at least one of a width and a height of the second coding unit 1322 having an NxN/2 size, and 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 the vertical direction and the horizontal direction to determine the third coding unit 1324 having an N/2×N/4 size.

According to an embodiment, the image decoding apparatus 100 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 may be determined by dividing the first coding unit 1300 having a size of 2Nx2N in a vertical direction, or a first coding unit 1310 having a size of 2NxN by splitting in a horizontal direction. Can be. According to an embodiment, when the depth is determined based on the length of the longest side of the coding unit, 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 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 illustrating a depth and a index (part index, PID) for classifying coding units, which may be determined according to types and sizes of coding units, according to an embodiment.

According to an embodiment, the image decoding apparatus 100 may determine a 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 video 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 units 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 that 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 video 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, and 1414c may include non-square second coding units 1414a and 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 in 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, and when 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 positioned at the center may include two of 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. In other words, discontinuity in the value of the index may exist. According to an embodiment, the apparatus 100 for decoding an image may determine whether odd numbered coding units are not the same size based on whether there is a discontinuity in 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 division 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 (eg, an upper left sample) of a predetermined position of each coding unit.

According to an embodiment, the image decoding apparatus 100 may determine an encoding unit at a predetermined location among the determined coding units, which are divided and determined using an index for classification of coding 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 image 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 when determining an index for classification of 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 middle 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 it 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 among different sizes 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 an 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 the 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, such a 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) that may include at least one reference coding unit. slice segment), maximum coding unit, etc.).

According to an embodiment, the receiving unit (not shown) of the image decoding apparatus 100 may acquire 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. have. 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 split, and the non-square type reference coding unit 1502 ) The process of determining at least one coding unit included in the above 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 (not shown) 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 ), only an index for identifying the size and shape of a reference coding unit can be obtained for each slice, slice segment, and maximum coding unit. 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, since the efficiency of use of the bitstream may be poor, the type of the reference coding unit Instead of directly acquiring information about the size of the reference coding unit and information about, 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 largest 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 maximum 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 that divides 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 Can be different for each processing block. The order of determination of the reference coding unit determined for each processing block is a raster scan, a Z-scan, an N-scan, an up-right diagonal scan, and a 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 on 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 (not shown) of the image decoding apparatus 100 may acquire information on 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 (not shown) may acquire 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 on the size of the obtained processing block. The size of at least one processing block may be determined, and the size of the 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 on 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 4 times the horizontal size of the reference coding unit and the vertical size to 4 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 receiving unit (not shown) 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 (not shown) is information related to the processing blocks 1602 and 1612 from a bitstream, and may obtain information on a reference coding unit determination order, and the image decoding apparatus 100 may process the processing block An order for determining at least one reference coding unit included in (1602, 1612) may be determined, and at least one reference coding unit included in the picture 1600 may be determined according to a determination order of the coding unit. 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 the decision order of the reference coding unit is obtained for each processing block, the 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 associated with 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 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.

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 determined in advance between the video decoding apparatus 100 and the video encoding apparatus 150. 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 150 and the video decoding apparatus 100 may determine in advance to determine a division rule based on a block form 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 a bitstream received from the video encoding apparatus 150.

The shape of the coding unit may include square and 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. In addition, . When 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.

The ratio of the width and height of the coding unit may include 1:2, 2:1, 1:4, 4:1, 1:8, 8:1, 1:16, or 16:1. Also, the direction of the coding unit may include a horizontal direction and a vertical direction. The horizontal direction may represent a case where the length of the width of the coding unit is longer than the length of the height. The vertical direction may indicate 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 image 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 a 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 150 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, a filter used for the current sample is determined based on at least one of the distance between the current sample and the reference sample in the current block and the size of the current block, and intra prediction is performed based on the determined filter. The video encoding/decoding method and apparatus to be described will be described in detail.

17 is a diagram illustrating intra prediction modes according to an embodiment.

Referring to FIG. 17, intra prediction modes according to an embodiment may include a planar mode (mode 0) and a DC mode (mode 1). In addition, the intra prediction modes may include an angular mode (2 to 66 modes) having a prediction direction. The angular mode may include a diagonal mode (#2 or 66 mode), a horizontal mode (#18 mode) and a vertical mode (#50 mode).

In the above, the intra prediction modes according to an embodiment have been described with reference to FIG. 17, but the present invention is not limited thereto, and various types of intra prediction modes may be obtained by adding a new intra prediction mode or subtracting an existing intra prediction mode. , It can be easily understood by those skilled in the art that the mode number of each intra prediction mode may vary depending on the case.

18 illustrates a method of generating a predictive sample of a current sample using a different filter based on at least one of a distance between a current sample and a reference sample and a size of a current block, according to an embodiment of the present disclosure It is a figure for illustration.

Referring to FIG. 18, the image decoding apparatus 100 generates predicted sample values for samples in the current block 1800 using reference samples 1820 to perform intra prediction for the current block 1800 can do.

For example, the apparatus 100 for decoding an image may use the current block 1800 from a current sample 1810 and a reference sample crossing an extension line 1830 in the prediction direction of the intra prediction mode of the current block 1800 and its adjacent samples. ), the predicted sample value p _x,y of the current sample 1810 may be determined according to Equation (1). Here, x,y may mean the x-coordinate and y-coordinate of the current sample based on the position of the upper-left sample of the current block.

In this case, f _k,i is the filter coefficient of i+1 th (0<=i<=3) for the k+1 th filter in a filter set including M+1 (M is an integer) filters. Can mean a ₀ means the sample value of the reference sample crossing the extension line 1830 from the current sample 1810, and a _-1 is just to the left of the reference sample crossing the extension line 1830 from the current sample 1810 Refers to the sample value of the reference sample being located, a ₁ means the sample value of the reference sample located immediately to the right of the reference sample crossing the extension line 1830 from the current sample 1810, and a ₂ is the current sample It may mean the sample value of the reference sample located second to the right from the reference sample crossing the extension line 1830 from 1810.

Above, the reference sample value according to equation (1) a _0, a _{-1, 1} a, but using a ₂ describes the information to generate a predicted sample value of the current sample, but not limited to, on the basis of a ₀ Those skilled in the art can understand that the sample values of various reference samples in the vicinity can be used to generate prediction values of the current sample. For example, predicted sample values of the current sample may be generated using a _-2 , a _-1 ,a ₀ ,a ₁ . Alternatively, a predicted sample value of the current sample may be generated using a ₀ ,a ₁ ,a ₂ ,a ₃ .

The video decoding apparatus 100 uses the current sample 1810 among the plurality of filters f _k (0<=k<=M) based on the distance between the current sample 1810 and the reference sample and the size of the current block 1800 You can decide which filter to be. For example, the image decoding apparatus 100 multiplies the size of the current block by a predetermined ratio, and determines a range of samples in which each of the plurality of filters f _k (0<=k<=M) is used, and the current sample The filter used in the range of the sample containing 1810 may be determined as the filter used in the current sample 1810. For example, the number of filters included in the filter set may be four. That is, the filter set may include filters f ₀ , f ₁ , f ₂ , and f ₃ .

The video decoding apparatus 100 has a distance between the current sample 1810 and a reference sample located above the current sample 1810 [0, size/4], or the left side of the current sample 1810 and the current sample 1810 When the distance between the reference samples located at [0, size/4], f ₀ may be determined as a filter used for the current sample 1810. In this case, size may be the size (height or width) of the current block 1800. In the video decoding apparatus 100, a distance between a current sample 1810 and a reference sample located above the current sample 1810 is [size/4, size/2], and the current sample 1810 and the current sample 1810 The distance between the reference samples located on the left side of is [size/4, size), or the distance between the samples located on the left side of the current sample 1810 and the current sample 1810 is [size/4, size/2), When the distance between the current sample 1810 and the sample located above the current sample 1810 is [size/4, size], f ₁ may be determined as a filter used for the current sample 1810. The video decoding apparatus 100 has a distance between the current sample 1810 and a reference sample located above the current sample 1810 [size/2, 3*size/4), and the current sample 1810 and the current sample ( The distance between the reference samples located on the left of 1810) is [size/2, size), or the distance between the samples located on the left of the current sample 1810 and the current sample 1810 is [size/2, 3*size/ 4), if the distance between the current sample 1810 and the sample located above the current sample 1810 is [size/2, size), f ₂ may be determined as a filter used for the current sample 1810. .

In the video decoding apparatus 100, a distance between a current sample 1810 and a reference sample located above the current sample 1810 is [3*size/4, size), and the current sample 1810 and the current sample 1810 The distance between the reference samples located on the left side of is [3*size/4, size), and the distance between the current sample 1810 and the sample located above the current sample 1810 is [3*size/4, size). In this case, f ₃ may be determined as a filter used in the current sample 1810.

That is, referring to FIG. 18, when the current sample 1810 is located in the first region 1850, the image decoding apparatus 100 may determine f ₀ as a filter used for the current sample 1810. When the current sample 1810 is located in the second region 1860, the video decoding apparatus 100 may determine f ₁ as a filter used for the current sample 1810. When the current sample 1810 is located in the third region 1870, the video decoding apparatus 100 may determine f ₂ as a filter used for the current sample 1810. When the current sample 1810 is located in the fourth region 1880, the video decoding apparatus 100 may determine f ₄ as a filter used for the current sample 1810.

At this time, the smoothing strength of the filters f ₀ , f ₁ , f ₂ , and f ₃ is the smallest filter f ₀ used for samples having a distance from the reference sample and the filter f ₃ used for samples having a distance from the reference sample. Can be the largest.

As described above, with reference to FIG. 18, it has been described that the image decoding apparatus 100 performs intra prediction on the current block using four filters for the current block 1800, but the image decoding apparatus is not limited thereto. It is understood by those skilled in the art that the 100 may perform intra prediction on the current block using various numbers of filters. At this time, a range of samples in which each filter is used may be variously determined based on the number of filters. For example, referring to FIG. 18, when the number of filters used in the current block 1800 is determined as three, the image decoding apparatus 100 integrates the third region 1870 and the fourth region 1880, When the current sample 1810 is located in the third area 1870 or the fourth area 1880, f ₃ may be determined as a filter used for the current sample 1810.

Alternatively, the video decoding apparatus 100 may determine in advance a range of samples in which each of the plurality of filters f _k (0<=k<=M) is used based on the distance between the sample in the current block and the reference sample, and the current sample The filter used for the range of the included sample can be determined as the filter used for the current sample.

For example, when the minimum distance among the vertical and horizontal distances between the current sample and the reference sample is less than 4, the video decoding apparatus 100 may determine f ₀ as a filter used for the current sample. When the minimum distance among the vertical and horizontal distances between the current sample and the reference sample is greater than or equal to 4 and less than 8, the video decoding apparatus 100 may determine f ₁ as a filter used for the current sample. When the minimum distance among the vertical and horizontal distances between the current sample and the reference sample is greater than or equal to 8 and less than 16, the video decoding apparatus 100 may determine f ₂ as a filter used for the current sample. When the minimum distance among the vertical and horizontal distances between the current sample and the reference sample is greater than or equal to 16 and less than 32, the video decoding apparatus 100 may determine f ₃ as a filter used for the current sample. When the minimum distance among the vertical and horizontal distances between the current sample and the reference sample is greater than or equal to 32 and less than 64, the video decoding apparatus 100 may determine f ₄ as a filter used for the current sample. When the minimum distance among the vertical and horizontal distances between the current sample and the reference sample is greater than 64, the video decoding apparatus 100 may determine f ₅ as a filter used for the current sample. In this case, the number of filters used for the current block may vary according to the size of the current block. The video decoding apparatus 100 may predetermine a range of samples in which each of the plurality of filters f _k (0<=k<=M) is used based on a minimum distance among vertical and horizontal distances between the current sample and the reference sample. Although described, the present invention is not limited thereto, and based on the intra prediction mode of the current block, a distance between a reference sample intersecting an extension line in a prediction direction from a current sample is determined, and a plurality of filters f _k (0<=k<=M) Those skilled in the art will appreciate that each can predetermine the range of samples used.

In addition, the image decoding apparatus 100 multiplies the size of the current block by a predetermined ratio, and determines a range of samples in which each of the plurality of filters f _k (0<=k<=M) is used in advance or Contents for determining a range of samples in which each of the plurality of filters f _k (0<=k<=M) are used based on the distance between the reference samples have been described, but are not limited thereto, the size of the current block and the current block Those skilled in the art will appreciate that a plurality of filters may determine the range of samples used by each of the various methods based on at least one of the distances between my sample and the reference sample.

Also, the apparatus 100 for decoding an image may determine the number of filters used in the current block based on the size (height or width) of the current block, and determine a filter corresponding to the number of filters. For example, if the size of the current block is greater than or equal to a predetermined size, the video decoding apparatus 100 filters the filters f _0, f _1, f _2,..., f _M-1 for the current block You can decide. When the size of the current block is smaller than a predetermined size, the video decoding apparatus 100 may determine the number of filters used in the current block as a predetermined number K (K is an integer) smaller than M. In this case, the video decoding apparatus 100 may determine a predetermined number of K filters by a predetermined combination among various possible combinations for the filters f _0, f _1, f _2,..., f _M-1 . . For example, the image decoding apparatus 100 may determine the filters f _0, f _1, f _2,..., f _K-1 as filters used for the current block. For example, when determining the number of filters used for the current block as two, the video decoding apparatus 100 may determine filters f _{0 and} f ₁ as filters used for the current block. Alternatively, if the number of filters used for the current block is 2, the video decoding apparatus 100 may determine filters f _{0 and} f _M-1 as filters used for the current block.

For example, the video decoding apparatus 100 may determine a set of 4 tap filters including filters f ₀ , f ₁ , f ₂ and f ₃ used for intra prediction for the current block as follows. For example, the image decoding apparatus 100 may determine the coefficient of the filter f ₀ as {-2,126, 4,0}. (The coefficient of the filter is of a filter applied to a specific fractional pixel postion) Coefficient means) The video decoding apparatus 100 may determine the coefficient of the filter f ₁ as {12, 99, 18, -1}. The video decoding apparatus 100 may determine the coefficient of the filter f ₂ as {21, 82, 23, 2}. The video decoding apparatus 100 may determine the coefficient of the filter f ₃ as {31, 63, 33, 1}. At this time, the filter f ₀ may be the filter having the weakest smoothing strength among the filters f ₀ ,f ₁ ,f ₂ ,f ₃ , and the filter f ₃ may have the most smoothing strength among the filters f ₀ ,f ₁ ,f ₂ ,f ₃ It can be a strong filter. On the other hand, those skilled in the art can understand that the values of the coefficients of the filter are not limited to the above-listed coefficients, and that the values of the coefficients of the filter may be used by being slightly changed (for example, +1 to 5, -1 to 5).

Meanwhile, the video decoding apparatus 100 may determine the number of reference samples used to determine the predicted sample value of the current sample based on the distance between the current sample and the reference sample. The video decoding apparatus 100 may filter the current sample using the reference sample corresponding to the number of reference samples.

For example, when the distance between the current sample and the reference sample is greater than or equal to a predetermined distance, the video decoding apparatus 100 performs prediction filtering on the current sample using M reference samples to obtain a predicted sample value of the current sample. Can be created. When the distance between the current sample and the reference sample is smaller than a predetermined distance, the image decoding apparatus 100 generates prediction sample values of the current sample by performing filtering on the current sample using a number of reference samples smaller than M You can. For example, when the distance between the current sample and the reference sample is less than a predetermined distance, the video decoding apparatus 100 may generate a predicted sample value of the current sample by performing filtering using one or two reference samples have. When the distance between the current sample and the reference sample is greater than or equal to a predetermined distance, the video decoding apparatus 100 may generate a predicted sample value of the current sample by performing filtering using four or more reference samples.

The image decoding apparatus 100 may determine the number of reference samples used for filtering the current sample by adjusting the number of taps of the filter. For example, when the distance between the current sample and the reference sample is greater than or equal to a predetermined distance, the video decoding apparatus 100 may determine a filter having 4 or more taps as a filter used for the current sample. When the distance between the current sample and the reference sample is smaller than a predetermined distance, the video decoding apparatus 100 may determine a 1-tap filter or a 2-tap filter as a filter used for the current sample. In this case, the video decoding apparatus 100 may not perform filtering instead of performing filtering using a 1-tap filter.

Alternatively, the video decoding apparatus 100 may determine the number of reference samples used for filtering the current sample by fixing the number of taps of the filter and adjusting the values of the coefficients of some filters.

For example, the video decoding apparatus 100 determines the number of taps of the filter as 4 taps, and when the distance between the current sample and the reference sample is smaller than a predetermined distance, the coefficient of the filter used for the current sample is {0,128,0, 0}. When the distance between the current sample and the reference sample is greater than or equal to a predetermined distance, the video decoding apparatus 100 may determine the coefficient of the filter used for the current sample as {32, 63, 31, 1}.

The image decoding apparatus 100 may determine a filter used for the current sample among filters used for the current block based on the location of the current sample in the current block, the intra prediction mode, and the size of the current block.

For example, when the x-axis coordinate value of the current sample is less than a predetermined value or the y-axis coordinate value of the current sample is less than a predetermined value, the image decoding apparatus 100 determines that the first filter is used, If not, it may be determined that the second filter is used.

At this time, the first filter has a smoothing strength smaller than that of the second filter, and may have sharp characteristics. At this time, the predetermined value may be 8. It is not limited thereto, and may be one of various values of multiples of 4.

When the index value of the intra prediction mode of the current block is less than or equal to the index value (DIA_IDX) of the 34th mode, the image decoding apparatus 100 has a width of the current block less than or equal to the first value, and the height of the current block It can be determined whether it is less than or equal to the second value. At this time, the first value may be smaller than the second value. For example, the first value may be 16 and the second value may be 32.

When the index value of the intra prediction mode of the current block is greater than the index value (DIA_IDX) of the 34th mode, the image decoding apparatus 100 determines whether the width of the current block is less than or equal to the first value, or the height of the current block is second. You can decide if it is less than or equal to the value. At this time, the first value may be greater than the second value. The first value may be 32, and the second value may be 16.

The video decoding apparatus 100 may determine a filter used for the current block based on the width and height of the current block. For example, when the width of the current block is less than or equal to the first value and the height of the current block is less than or equal to the second value, the video decoding apparatus 100 uses f0 _and f ₁ as filters used in the current block. Can decide. When the width of the current block is greater than the first value or the width of the current block is greater than the second value, the image decoding apparatus 100 may determine f ₂ and f ₃ as filters used for the current block.

FIG. 19 shows a right or upper reference line according to a coding order flag, in which a coding order between coding units is determined in a forward or reverse direction based on a coding order flag, and the determined coding code order is determined in a forward or reverse direction. This is a diagram for explaining that it can be used for intra prediction.

Referring to FIG. 19, the largest coding unit 2950 is divided into a plurality of coding units (1956, 1958, 1960, 1962, 1968, 1970, 1972, 1974, 1980, 1982, 1984, 1986). The largest coding unit 1950 corresponds to the highest node 1900 of the tree structure. In addition, a plurality of coding units (1956, 1958, 1960, 1962, 1968, 1970, 1972, 1974, 1980, 1982, 1984, 1986) each of a plurality of nodes (1906, 1908, 1910, 1912, 1918, 1920, 1922, 1924, 1930, 1932, 1934, 1936). The top coding order flags 1902, 1914, 1926 indicating the coding order in the tree structure correspond to the arrows 1952, 1964, 1976, and the top coding order flags 1904, 1916, 1928 are arrows 1954, 1966, 1978 ).

The upper coding order flag indicates a coding order of two coding units located at the top of coding units of the same depth. If the upper encoding order flag is 0, encoding is performed in the forward direction. Conversely, when the upper encoding order flag is 1, encoding is performed in the reverse direction.

Similarly, the lower coding order flag indicates the coding order of two coding units located at the bottom of the coding units having the same depth. If the lower encoding order flag is 0, encoding is performed in the forward direction. Conversely, when the lower encoding order flag is 1, encoding is performed in the reverse direction.

For example, since the upper coding order flag 1914 is 0, the coding order between coding units 1968 and 1970 is determined from left to right, which is the forward direction. In addition, since the lower coding order flag 1916 is 1, the coding order between coding units 1972 and 1974 is determined from the right side to the left side.

According to an embodiment, the upper coding order flag and the lower coding order flag may be set to have the same value. For example, when the upper coding order flag 1902 is determined to be 1, the lower coding order flag 1904 corresponding to the upper coding order flag 1902 may also be determined to be 1. Since the values of the upper coding order flag and the lower coding order flag are determined in 1 bit, the information amount of the coding order information decreases.

According to an embodiment, the top coding order flag and the bottom coding order flag of the current coding unit may be determined by referring to at least one of a top coding order flag and a bottom coding order flag applied to a coding unit having a depth lower than that of the current coding unit. For example, the upper coding order flag 1926 and the lower coding order flag 1928 applied to the coding units (1980, 1982, 1984, 1986) are the lower coding order flags 1916 applied to the coding units (1972, 1974). It can be determined based on. Accordingly, the upper coding order flag 1926 and the lower coding order flag 1928 may be determined to be the same values as the coding order flag 1916. Since the values of the upper coding order flag and the lower coding order flag are determined from the upper coding unit of the current coding unit, coding order information is not obtained from the bitstream. Therefore, the amount of information in the encoding order information decreases.

In this case, the image decoding apparatus 100 includes data of samples included in the right neighboring coding unit 1958 decoded before the current coding unit 1986 and data of samples included in the upper neighboring coding unit (1980, 1982). Since is available, the data of the samples (right reference line) included in the right neighboring coding unit 1958 and the data of the samples (upper reference line) included in the upper neighboring coding unit (1980,1982) are used. Prediction according to an embodiment of the present disclosure may be performed.

That is, referring to FIGS. 17 to 18, the filter used for the current sample is determined based on at least one of the size of the current block and the distance between the current sample and the reference sample, and intra prediction is adaptively performed based on the determined filter A method and apparatus have been described, and intra prediction is performed based on reference samples adjacent to the upper or left corners of the current block on the premise that the decoding is performed according to the decoding order of the conventional coding unit. Although the contents have been described, the present invention is not limited thereto, and when the sub/decoding order between some adjacent coding units is in the reverse order of the right coding unit and the left coding unit as shown in FIG. 19, a reference sample adjacent to the upper or right edge of the current block Those skilled in the art can readily understand that intra prediction can be performed based on these.

According to various embodiments of the present disclosure, prediction accuracy may be improved and a natural pattern prediction block may be generated by adaptively determining a filter used for the current sample based on a distance between the current sample and the reference sample.

That is, the prediction accuracy can be improved by using a filter having a small smoothing strength and sharp characteristics for a sample close to the reference sample. Also, a natural pattern prediction block may be generated for a sample far from the reference sample by using a filter having a high smoothing intensity.

In addition, by generating a prediction block having a natural pattern and a high prediction accuracy, correction of a sudden prediction error is indicated, and thus, the efficiency of transformation can be improved.

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 scope equivalent thereto 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 on 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)

Obtaining information about a transform coefficient of a current block from a bitstream;
Determining a filter used for the current sample based on at least one of a distance between a current sample in a current block and a reference sample, and a size of the current block;
Obtaining a prediction block of a current block including a prediction sample of the current sample generated using the determined filter;
Obtaining a residual block of the current block based on the information on the transform coefficient of the obtained current block; And
And reconstructing the current block based on the prediction block of the current block and the residual block of the current block. According to claim 1,
Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block,
And determining a type of a filter used in the current sample and a coefficient of the filter based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block. Video decoding method. According to claim 2,
The filter type is a low pass filter, a Gaussian filter, a bilateral filter, a uniform filter, a bilinear interpolation filter, and a cubic filter ( A video decoding method characterized in that it is one of a cubic filter) and a DCT (Discrete Cosign Transform) filter (DCT filter). According to claim 1,
The number of taps of a filter used for the current sample is a predetermined value, or is determined based on at least one of a distance between the current sample and the reference sample and the size of the current block. According to claim 1,
Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block,
Determining a plurality of filters for the current block based on at least one of a size of the current block and a distance between a sample in the current block and a reference sample; And
And determining a filter corresponding to the current sample among a plurality of filters for the current block. The method of claim 5,
Determining a plurality of filters for the current block based on at least one of a size of the current block and a distance between a sample in the current block and a reference sample,
And determining a plurality of filters for the current block based on a ratio of a height or a width of the current block and a distance between a sample in the current block and a reference sample. According to claim 1,
Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block,
Determining a first reference sample corresponding to a sample in the current block based on the intra prediction mode of the current block;
Determining a plurality of filters for the current block based on a distance between the sample and a first reference sample; And
And determining a filter corresponding to the current sample among a plurality of filters for the current block. According to claim 1,
Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block,
Determining the number of filters used for the current block based on the size of the current block, and determining a filter for the current block corresponding to the number of filters; And
And determining a filter used for the current sample among filters for the current block based on at least one of a distance between the current sample and a reference sample and the size of the current block. According to claim 1,
Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block,
And determining a filter used for the current sample based on at least one of an intra prediction mode of the current block and a shape of the current block. According to claim 1,
Determining a filter used for the current sample based on at least one of an intra prediction mode of the current block and a shape of the current block,
If the intra prediction mode of the current block is a predetermined intra prediction mode, determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block. Video decoding method comprising a. According to claim 1,
Determining a filter used for the current sample based on the intra prediction mode of the current block and the shape and at least one of the current block,
When the width of the current block is less than or equal to a predetermined first value, and the height of the current block is less than or equal to a predetermined second value, the distance between the current sample and the reference sample in the current block and the size of the current block And determining a filter used for the current sample based on at least one of the above. According to claim 1,
Determining a filter used for the current sample based on at least one of a distance between a current sample and a reference sample in the current block and a size of the current block,
If the distance between the current sample and the reference sample is less than a predetermined value, a first filter for the current sample is determined, and when the distance between the current sample and the reference sample is greater than a predetermined value, the first filter for the current sample is 2 determining a filter,
The smoothing strength of the first filter is smaller than the smoothing strength of the second filter. The method of claim 4,
The predetermined value is an integer of 4 or more, characterized in that the video decoding method. Determining a filter used for the current sample based on at least one of a distance between a current sample in a current block and a reference sample, and a size of the current block;
Generating a prediction block of a current block including a prediction sample of the current sample generated using the determined filter; And
And encoding information on transform coefficients of the current block based on the prediction block of the current block. Obtain information about a transform coefficient of a current block from a bitstream,
Determine a filter used for the current sample based on at least one of a distance between a current sample in a current block and a reference sample, and a size of the current block,
Obtaining a prediction block of a current block including a prediction sample of the current sample generated using the determined filter,
A processor that obtains a residual block of the current block based on information on the transform coefficient of the obtained current block, and restores the current block based on a prediction block of the current block and a residual block of the current block. Video decoding apparatus comprising a.

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