KR102606290B1 - Method and apparatus for image encoding, and method and apparatus for image decoding - Google Patents

Abstract

A step of hierarchically dividing the chroma image based on the segmentation mode of blocks in the chroma image of the current image, determining a plurality of coding units in the chroma image, and decoding the current image based on the plurality of coding units in the chroma image. A video decoding method including: At this time, the step of determining the plurality of coding units in the chroma image includes the size of one chroma block among the plurality of chroma blocks to be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image. Or, if the area is less than or equal to a predetermined size or area, not allowing division of the current chroma block based on the division type mode of the current chroma block, and determining at least one coding unit included in the current chroma block. can do.

Description

Image encoding method and apparatus, image decoding method and apparatus {Method and apparatus for image encoding, and method and apparatus for image decoding}

The method and device according to an embodiment can encode or decode an image using various types of coding units included in the image. The method and device according to an embodiment may hierarchically divide a chroma image, determine at least one coding unit, and encode or decode the chroma image using the at least one coding unit.

As hardware capable of playing and storing high-resolution or high-definition video content is developed and distributed, the need for a codec that effectively encodes or decodes high-resolution or high-definition video content is increasing. Encoded video content can be played by being decoded. Recently, methods have been implemented to effectively compress such high-resolution or high-definition video content. For example, an efficient image compression method is being implemented through the process of processing the image to be encoded in a random manner.

Various data units may be used to compress images, and an inclusion relationship may exist between these data units. In order to determine the size of the data unit used for video compression, the data unit can be divided by various methods, and an optimized data unit is determined according to the characteristics of the video, so that the video can be encoded or decoded.

An image decoding method according to an embodiment of the present disclosure includes the steps of hierarchically dividing the luma image based on a segmentation mode of blocks included in the luma image of a current image and determining a plurality of coding units in the luma image; determining a plurality of coding units in the chroma image by hierarchically dividing the chroma image based on a segmentation mode of blocks in the chroma image of the current image; and decoding the current image based on a plurality of coding units in the determined luma image and a plurality of coding units in the chroma image, wherein the partition type mode is based on at least one of a block partition direction and a partition type. mode, and the step of determining a plurality of coding units in the chroma image includes one of a plurality of chroma blocks to be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image. If the size or width of the chroma block is less than or equal to a predetermined size or area, division of the current chroma block based on the division type mode of the current chroma block is not allowed, and at least one coding unit included in the current chroma block It is characterized by including the step of determining.

An image decoding device according to an embodiment of the present disclosure determines a plurality of coding units in the luma image by hierarchically dividing the luma image based on the division type mode of blocks included in the luma image of the current image, The chroma image is hierarchically divided based on the division type mode of blocks in the chroma image of the current image to determine a plurality of coding units in the chroma image, and a plurality of coding units in the determined luma image and a plurality of coding units in the chroma image are determined. and at least one processor that decodes the current image based on a coding unit, wherein the partition type mode is a mode based on at least one of a partition direction and a partition type of a block, and the at least one processor decodes the current image in the chroma image. When determining a plurality of coding units, the size or area of one chroma block among a plurality of chroma blocks to be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image is predetermined. If it is less than or equal to the size or width, the at least one processor does not allow division of the current chroma block based on the division type mode of the current chroma block and determines at least one coding unit included in the current chroma block. It is characterized by

An image decoding method according to an embodiment of the present disclosure includes the steps of hierarchically dividing a luma image based on the division type mode of blocks included in the luma image of a current image and determining a plurality of coding units in the luma image; determining a plurality of coding units in the chroma image by hierarchically dividing the chroma image based on the segmentation mode of blocks in the chroma image of the current image; And encoding the current image based on a plurality of coding units in the determined luma image and a plurality of coding units in the chroma image,

The division type mode is a mode based on at least one of the division direction and division type of the block,

The step of determining a plurality of coding units in the chroma image includes:

When the size or area of one chroma block among a plurality of chroma blocks to be created by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image is smaller than or equal to a predetermined size or area. , disallowing division of the current chroma block based on the division type mode of the current chroma block, and determining at least one coding unit included in the current chroma block.

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

FIG. 1A shows a block diagram of an image decoding device according to various embodiments.
FIG. 1B shows a flowchart of an image decoding method according to various embodiments.
Figure 1C shows a block diagram of an image decoder according to various embodiments.
FIG. 2A shows a block diagram of an image encoding device according to various embodiments.
FIG. 2B shows a flowchart of an image encoding method according to various embodiments.
Figure 2C shows a block diagram of an image decoder according to various embodiments.
FIG. 3 illustrates a process in which an image decoding device divides a current coding unit and determines at least one coding unit, according to an embodiment.
FIG. 4 illustrates a process in which an image decoding apparatus divides a coding unit in a non-square shape and determines at least one coding unit, according to an embodiment.
FIG. 5 illustrates a process by which an image decoding apparatus divides a coding unit based on at least one of block type information and information about a split type mode, according to an embodiment.
FIG. 6 illustrates a method by which an image decoding apparatus determines a predetermined coding unit among an odd number of coding units, according to an embodiment.
FIG. 7 illustrates the order in which the plurality of coding units are processed when the video decoding device divides the current coding unit to determine a plurality of coding units, according to an embodiment.
FIG. 8 illustrates a process in which an image decoding device determines that the current coding unit is divided into an odd number of coding units when coding units cannot be processed in a predetermined order, according to an embodiment.
FIG. 9 illustrates a process in which an image decoding device divides a first coding unit and determines at least one coding unit, according to an embodiment.
FIG. 10 illustrates that, according to one embodiment, when a non-square second coding unit determined by dividing a first coding unit satisfies a predetermined condition, the form in which the second coding unit can be divided is limited. shows that
FIG. 11 illustrates a process in which an image decoding apparatus splits a square-shaped coding unit when information about the split mode cannot indicate splitting into four square-shaped coding units, according to an embodiment.
FIG. 12 illustrates that the processing order between a plurality of coding units may vary depending on the division process of the coding unit, according to one embodiment.
FIG. 13 illustrates a process in which the depth of the coding unit is determined as the shape and size of the coding unit change when the coding unit is recursively divided to determine a plurality of coding units according to an embodiment.
FIG. 14 illustrates an index (part index, hereinafter PID) for classifying depth and coding units that can be determined according to the shape and size of coding units, according to an embodiment.
FIG. 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.
FIG. 16 illustrates a processing block that serves as a standard for determining the decision order of a reference coding unit included in a picture, according to an embodiment.
FIGS. 17A and 17B are diagrams for explaining a method of disallowing division into chroma blocks of a certain size or less when the division tree type is a single tree, according to various embodiments.
FIG. 18 is a diagram illustrating a method of disallowing division into chroma blocks of a certain size or less when the division tree type is a dual tree, according to one embodiment.
FIG. 19 is a diagram illustrating a method of dividing a block located at a picture boundary using a division type mode based on the direction of the picture boundary, according to an embodiment.
20A to 20B show a method of dividing a block at the border of a picture based on whether a block of the minimum size appears when binary dividing a block at the border of a picture by applying an allowable binary division depth according to an embodiment. This is a drawing to explain.

Best mode for carrying out the invention

An image decoding method according to an embodiment of the present disclosure includes the steps of hierarchically dividing the luma image based on a segmentation mode of blocks included in the luma image of a current image and determining a plurality of coding units in the luma image; determining a plurality of coding units in the chroma image by hierarchically dividing the chroma image based on a segmentation mode of blocks in the chroma image of the current image; and decoding the current image based on a plurality of coding units in the determined luma image and a plurality of coding units in the chroma image, wherein the partition type mode is based on at least one of a block partition direction and a partition type. mode,

The step of determining a plurality of coding units in the chroma image includes:

When the size or area of one chroma block among a plurality of chroma blocks to be created by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image is smaller than or equal to a predetermined size or area. , disallowing division of the current chroma block based on the division type mode of the current chroma block, and determining at least one coding unit included in the current chroma block.

The split type may represent one of binary split, tri split, and quad split.

The predetermined size may be one of 4x2, 2x4, and 2x2.

The predetermined area may be one of 8 and 4.

When the size or area of one chroma block among a plurality of chroma blocks to be created by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image is smaller than or equal to a predetermined size or area. , The step of not allowing division of the current chroma block based on the division type mode of the current chroma block and determining at least one coding unit included in the current chroma block includes the size or area of the current chroma block and the current chroma block. Depending on whether the condition based on the division type mode of the chroma block is satisfied, the size or area of one chroma block among a plurality of chroma blocks to be created by dividing the current chroma block in the chroma image is smaller than a predetermined size or area. determining whether they are equal; and determining, according to the result of the determination, not to allow division of the current chroma block based on the division type mode of the current chroma block, and determining at least one coding unit included in the current chroma block. You can.

The condition based on the size or width of the current chroma block and the division type mode of the current chroma block is, when the division type of the current chroma block indicates quad division, the width or height of the current chroma block. ) may be a condition regarding whether is less than or equal to 4.

The condition based on the size or width of the current chroma block and the partition type mode of the current chroma block is, when the partition type of the current chroma block indicates binary partition, whether the width of the current chroma block is less than or equal to 16. It may be a condition.

Conditions based on the size or area of the current chroma block and the division type mode of the current chroma block are:

When the division type of the current chroma block indicates trie division, the condition may be whether the area of the current chroma block is less than or equal to 32.

The segmentation mode of blocks in the chroma image of the current image may be independent of the segmentation mode of blocks included in the luma image of the current image.

The segmentation mode of blocks in the chroma image of the current image is dependent on the segmentation mode of corresponding blocks in the luma image of the current image corresponding to the blocks in the chroma image, and the size of the block in the chroma image is dependent on the segmentation mode of the blocks in the luma image of the current image. It may be determined based on the chroma sub sampling format and the size of the corresponding block in the luma image.

The size of one block among a plurality of blocks to be generated by dividing the current chroma block of the chroma image based on the division type mode of the current chroma block in the chroma image is greater than 2xN (N is an integer greater than or equal to 2) or Nx2. If less than or equal to the current chroma block, determining that division of the current chroma block is not permitted based on the division type mode of the current chroma block, and determining at least one coding unit included in the current chroma block.

The step of hierarchically dividing the luma image based on the division type mode of blocks included in the luma image of the current image and determining a plurality of coding units in the luma image includes the step of determining a plurality of coding units in the luma image. When located on the right border of , obtaining a flag indicating a partition type of one of binary partition and quad partition from the bitstream; and determining at least one coding unit included in the current luma block based on the obtained flag.

An image decoding device according to an embodiment of the present disclosure determines a plurality of coding units in the luma image by hierarchically dividing the luma image based on the division type mode of blocks included in the luma image of the current image, The chroma image is hierarchically divided based on the division type mode of blocks in the chroma image of the current image to determine a plurality of coding units in the chroma image, and a plurality of coding units in the determined luma image and a plurality of coding units in the chroma image are determined. and at least one processor that decodes the current image based on a coding unit, wherein the partition type mode is a mode based on at least one of a partition direction and a partition type of a block, and the at least one processor decodes the current image in the chroma image. When determining a plurality of coding units, the size or area of one chroma block among a plurality of chroma blocks to be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image is predetermined. If it is less than or equal to the size or width, the at least one processor may not allow division of the current chroma block based on the division type mode of the current chroma block and may determine at least one coding unit included in the current chroma block. there is.

An image encoding method according to an embodiment of the present disclosure includes the steps of hierarchically dividing a luma image based on the division type mode of blocks included in the luma image of a current image and determining a plurality of coding units in the luma image; determining a plurality of coding units in the chroma image by hierarchically dividing the chroma image based on the segmentation mode of blocks in the chroma image of the current image; And encoding the current image based on a plurality of coding units in the determined luma image and a plurality of coding units in the chroma image, wherein the partition type mode is based on at least one of a block partition direction and a partition type. mode, and the step of determining a plurality of coding units in the chroma image includes one of a plurality of chroma blocks to be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image. If the size or width of the chroma block is less than or equal to a predetermined size or area, division of the current chroma block based on the division type mode of the current chroma block is not allowed, and at least one coding unit included in the current chroma block It may include a step of determining.

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

Forms for practicing the invention

Advantages and features of the disclosed embodiments and methods for achieving them will become clear by referring to the embodiments described below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the present disclosure is complete and to those skilled in the art to which the present disclosure pertains. It is only provided to fully inform the user of the scope of the invention.

Terms used in this specification will be briefly described, and the disclosed embodiments will be described in detail.

The terms used in this specification are general terms that are currently widely used as much as possible while considering the function in the present disclosure, but this may vary depending on the intention or precedent of a technician working in the related field, the emergence of new technology, etc. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the relevant invention. Therefore, the terms used in this disclosure should be defined based on the meaning of the term and the overall content of this disclosure, rather than simply the name of the term.

In this specification, singular expressions include plural expressions, unless the context clearly specifies the singular.

When it is said that a part "includes" a certain element throughout the specification, this means that, unless specifically stated to the contrary, it does not exclude other elements but may further include other elements.

Additionally, the term “unit” used in the specification refers to a software or hardware component, and the “unit” performs certain roles. However, “wealth” is not limited to software or hardware. The “copy” may be configured to reside on an addressable storage medium and may be configured to run on one or more processors. Thus, as an example, “part” refers to software components, such as object-oriented software components, class components, and task components, processes, functions, properties, procedures, Includes subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and “parts” may be combined into smaller numbers of components and “parts” or may be further separated into additional components and “parts”.

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

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

Hereinafter, “video” may refer to a static image such as a still image of a video or a dynamic image such as a moving image, that is, the video itself.

Hereinafter, “sample” refers to data assigned to a sampling position of an image and is subject to processing. For example, in an image in the spatial domain, pixel values and transform coefficients in the transform domain may be samples. A unit containing at least one sample can be defined as a block.

*Below, with reference to the attached drawings, the embodiments will be described in detail so that those skilled in the art can easily perform them. In order to clearly explain the present disclosure in the drawings, parts unrelated to the description are omitted.

Hereinafter, an image encoding device, an image decoding device, an image encoding method, and an image decoding method according to various embodiments will be described in detail with reference to FIGS. 1 to 20. A method of determining a data unit of an image according to various embodiments is described with reference to FIGS. 3 to 16, and various types of coding units according to various embodiments with reference to FIGS. 1, 2, and 17 to 20. Based on this, an image encoding device, an image decoding device, an image encoding method, and an image decoding method for encoding or decoding an image are described.

Hereinafter, with reference to FIGS. 1 and 2, an encoding/decoding method and device for encoding or decoding an image based on various types of coding units according to an embodiment of the present disclosure will be described in detail.

FIG. 1A shows a block diagram of an image decoding device according to various embodiments.

The image decoding device 100 according to various embodiments may include a coding unit determination unit 105 and an image decoding unit 110. The coding unit determination unit 105 and the image decoding unit 110 may include at least one processor. Additionally, the coding unit determination unit 105 and the image decoding unit 110 may include a memory that stores instructions to be performed by at least one processor. The image decoder 110 may be implemented as hardware separate from the coding unit determination unit 105, or may include the coding unit determination unit 105.

The coding unit determiner 105 may determine a plurality of coding units in the luma image by hierarchically dividing the luma image based on the division type mode of blocks included in the luma image of the current image.

The coding unit determination unit 105 may determine a plurality of coding units in the chroma image by hierarchically dividing the chroma image based on the division type mode of blocks in the chroma image of the current image.

The coding unit determination unit 105 determines the size or area of one chroma block among a plurality of chroma blocks that can be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image by a predetermined amount. You can determine whether it is less than or equal to the size or area. The division type mode of the current chroma block may be a mode based on at least one of the division direction and division type of the block.

According to the result of the above determination, the coding unit determination unit 105 may determine that division of the current chroma block is not permitted based on the division type mode of the current chroma block.

The coding unit determination unit 105 may determine at least one coding unit included in the current chroma block based on one of the split type modes of the current block that are allowed except for the split type mode determined not to be allowed. . If there is no partition type mode of the current block that is allowed, the coding unit determination unit 105 may determine the current chroma block as the coding unit without further partitioning.

The coding unit determination unit 105 determines the size or area of one chroma block among a plurality of chroma blocks that can be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image by a predetermined amount. If it is determined that it is less than or equal to the size or width, it may be determined that division of the current chroma block is not allowed based on the division type mode of the current chroma block. At this time, the predetermined size may be one of 4x2, 2x4, and 2x2. Additionally, the predetermined area may be one of 8 and 4.

The coding unit determination unit 105 selects one of a plurality of blocks that can be generated by dividing the current chroma block in the chroma image according to whether conditions based on the size or area of the current chroma block and the division type mode of the current chroma block are satisfied. It can be determined whether the size or area of one chroma block is smaller than or equal to a predetermined size or area. At this time, the condition based on the size or width of the current chroma block and the division type mode of the current block is a condition for whether the width or height of the current chroma block is less than or equal to 4 if the division type of the current chroma block is quad division. It can be. When the partition type of the current chroma block indicates quad partition, the coding unit determination unit 105 may determine that partition based on quad partition is not permitted if the size or width of the current chroma block is less than or equal to 4. That is, if the height or width of the current chroma block is less than or equal to 4, the height or width of one chroma block among a plurality of chroma blocks created by quad-dividing the current chroma block may be less than or equal to 2. Therefore, the size of one chroma block among the plurality of chroma blocks generated by quad-dividing the current chroma block may be 2x2, 4x2, 2x4 (or smaller), and the size of this block is accepted as a coding unit and encoded. In this case, it may be decided not to allow quad-splitting of the current block to improve throughput because this may result in reduced throughput.

The coding unit determination unit 105 may split the current chroma block based on other allowable split types except quad split. If there is no split type allowed in the current chroma block, the coding unit determination unit 105 may determine the current chroma block as the coding unit without further splitting.

The condition based on the size or width of the current chroma block and the division type mode of the current block may be a condition regarding whether the width of the current chroma block is less than or equal to 16 when the division type of the current chroma block indicates binary division. When the division type of the current chroma block indicates binary division, the coding unit determination unit 105 may determine that division based on binary division is not permitted if the area of the current chroma block is less than or equal to 16. That is, if the width of the current chroma block is less than or equal to 16 (for example, if the size of the current chroma block is less than or equal to 2x8, 8x2, or 4x4), multiple chromas are generated by binary dividing the current chroma block. The size of one chroma block among the blocks may be less than or equal to 2x4 or 4x2. When encoding by allowing the size of such a block as a coding unit, throughput may be reduced, so it may be decided not to allow binary division of the current block in order to improve throughput. The coding unit determination unit 105 may split the current chroma block based on other allowable split types except binary split. If there is no split type allowed in the current chroma block, the coding unit determination unit 105 may determine the current chroma block as the coding unit without further splitting.

The condition based on the size or width of the current chroma block and the partition type mode of the current block is whether the width of the current chroma block is less than or equal to 32, if the partition type of the current chroma block is tri-partition (also called triple partition). It may be a condition for. When the division type of the current chroma block indicates trie division, the coding unit determination unit 105 may determine that division based on binary division is not permitted if the area of the current chroma block is less than or equal to 32. That is, if the area of the current chroma block is less than or equal to 32 (for example, if the size of the current chroma block is less than or equal to 4x8, 8x4, 2x16, 16x2), a plurality of The size of one of the chroma blocks may be less than or equal to 2x4 or 4x2. When encoding by allowing the size of such a block as a coding unit, throughput may be reduced, so it may be decided not to allow tri-division of the current block to improve throughput. The coding unit decision unit 105 may split the current chroma block based on other allowable split types other than trie split. If there is no split type allowed in the current chroma block, the coding unit determination unit 105 may determine the current chroma block as the coding unit without further splitting.

The segmentation mode of blocks in the chroma image of the current image may be independent of the segmentation mode of blocks included in the luma image of the current image, but is not limited to this, and the segmentation mode of blocks in the chroma image of the current image may be independent of the segmentation mode of blocks included in the luma image of the current image. The segmentation type mode of corresponding blocks in the luma image of the current image corresponding to blocks in the image may be dependent on the mode.

*That is, the coding unit determination unit 105 divides the luma image hierarchically based on the division type mode of blocks included in the luma image of the current image to determine a plurality of coding units in the luma image and include them in the luma image. A plurality of coding units in the chroma image can be determined by hierarchically dividing the chroma image based on the segmentation mode of the blocks included in the chroma image and the segmentation mode of the blocks included in the same chroma image. At this time, the coding unit determination unit 105 may determine the size of a block in the chroma image based on the chroma subsampling method of the current image and the size of the corresponding block of the luma image. For example, if the chroma subsampling method is YUV 4:2:0 and the size of the corresponding block of the luma image is 16x16, the size of the block in the chroma image may be determined to be 8x8.

The coding unit determiner 105 determines that the size of one block among a plurality of blocks generated by dividing the current chroma block of the chroma image based on the division type mode of the current chroma block in the chroma image is 2xN (N is greater than 2 or equal integer) or less than or equal to Nx2, it may be determined that division of the current chroma block is not permitted based on the division type mode of the current chroma block. The coding unit determination unit 105 may determine at least one coding unit included in the current chroma block based on the remaining allowable split types excluding the impermissible split types.

The image decoder 110 may decode the current image based on a plurality of coding units in the luma image and a plurality of coding units in the chroma image.

Meanwhile, each luma block divided from each inter slice or picture may have a different prediction mode. For example, each luma block may have an inter or intra prediction mode. In this case, the image decoding apparatus 100 may determine the prediction mode of the corresponding chroma block as follows. When the current slice or picture is an inter slice or picture, the video decoding apparatus 100 sets the prediction mode of the chroma block if the ratio of the area of the luma block with an intra prediction mode to the area of the luma block is greater than or equal to a predetermined value. can be determined as the intra prediction mode.

When the current slice or picture is an inter slice or picture, the video decoding apparatus 100 sets the prediction mode of the chroma block if the ratio of the area of the luma block with the inter prediction mode to the area of the luma block is greater than or equal to a predetermined value. can be determined as the inter prediction mode.

When a luma block of a specific size is divided, the image decoding apparatus 100 may obtain information about the prediction mode of the corresponding chroma block from the bitstream.

The image decoding apparatus 100 may determine the prediction mode of the luma corresponding block corresponding to a specific position of the chroma block as the prediction mode of the chroma block. For example, the specific location may be an upper left location, a center location, a lower left location, an upper location, a lower right location, etc. At this time, the specific location may be a predefined location, but is not limited to this, and the video decoding device 100 may obtain information about the specific location from a separate bitstream and determine the specific location based on the obtained information. there is.

In order to improve throughput, the image decoding device 100 may perform the following operations when the size of the current block is smaller than or equal to a specific size or when the width of the current block is smaller than or equal to a specific value.

The image decoding apparatus 100 may inversely transform the current block using a transformation method other than a transformation method such as DCT (Discrete Cosine Transform). For example, if the size of the current block is smaller than 4x4, the image decoder 105 may inversely transform the current block using the Hadamard transform.

The video decoding device 100 may always set the value of the transform skip flag for the current block to 1. For example, the video decoding apparatus 100 may obtain the transform skip flag for the current block from the bitstream and set the value of the transform skip flag based on the value of the transform skip flag obtained from the bitstream. If the size of the current block is smaller than or equal to a specific size, or if the width of the current block is smaller than or equal to a specific value, the value of the conversion skip flag for the current block is set to 1 without obtaining the conversion skip flag from the bitstream. It can be set to .

The transform skip flag is a flag that indicates whether transform is used. When its value is 0, the image decoding device 100 does not perform an inverse transform operation and can restore the current block using the inverse quantized block, and the If the value is 1, the image decoding apparatus 100 may perform an inverse transformation on the inverse quantized block to generate an inversely transformed block, and restore the current block using the inversely transformed block.

Additionally, the video decoding apparatus 100 may determine that division of the block is not permitted when the size of the block is smaller than or equal to a specific size or area. For example, if the size of the current block is 8x8, the video decoding apparatus 100 may determine that division of the current block is not allowed. Additionally, for example, if the width of the current block is 64, the video decoding apparatus 100 may determine that division of the current block is not allowed.

In the case of an inter slice or picture, the probability of splitting a block may be lower than the probability of skipping a block, so the image decoding apparatus 100 may perform the following operations.

The video decoding apparatus 100 may obtain skip information of the current block from the bitstream before segmentation information of the current block.

Additionally, the video decoding device 100 obtains flag information indicating whether the maximum coding unit has residual information at the maximum coding unit level, and if the value of this flag indicates that the maximum coding unit does not have residual information. In this case, the video decoding apparatus 100 may determine not to parse syntax elements related to the residual from the bitstream and to skip the decoding process related thereto.

Additionally, the video decoding apparatus 100 may determine that asymmetric binary division is not permitted in the case of inter slices or pictures.

When the current block is located on the boundary of a picture, the video decoding apparatus 100 can split the current block without obtaining additional information from the bitstream. For example, when the current block is located on the boundary of a picture, the video decoding apparatus 100 may quad-split the current block without obtaining separate information from the bitstream. At this time, quad division may be performed recursively until the divided block is not located on the border of the picture. However, if there is a predetermined division depth, the block may be divided up to that depth.

Meanwhile, when the current block is located on the border of a picture, the video decoding device 100 can split the current block without obtaining separate information from the bitstream, but splits the current block based on various split types and split directions. can do. At this time, the image decoding apparatus 100 may determine the division type and division direction of the current block based on the boundary condition of the block. Here, the divided block may be divided recursively until it is not located on the boundary of the picture. However, if there is a predetermined division depth, the block may be divided up to that depth.

For example, when the current block is located on the lower border of the picture, the video decoding device 100 determines the division direction of the current block to be horizontal, and determines the division type to be binary division (or tri division), Based on the division direction and division type of the current block, the current block can be binary divided (or tri-divided) in the horizontal direction.

When the current block is located on the right border of the picture, the video decoding device 100 determines the division direction of the current block to be vertical, determines the division type of the current block as binary division (or tri division), and Based on the division direction and division type of the block, the current block can be binary divided (or tri-divided) in the vertical direction.

When the current block is located on the lower right border of the picture, the video decoding apparatus 100 may determine the partition type of the current block to be quad partition and quad partition the current block based on the partition type of the current block.

As the split types or directions of allowable blocks become more diverse, the complexity increases exponentially, and the video decoding device 100 limits some of the various split types or directions to reduce complexity. can do.

For example, the video decoding apparatus 100 may limit the division depth of binary division. The video decoding apparatus 100 may limit the ratio of allowable blocks or the size of allowable blocks.

The video decoding apparatus 100 can split a block without obtaining separate information from the bitstream using only the split type mode that satisfies the above restriction conditions.

When the current block is located on the boundary of a picture, the image decoding apparatus 100 may allow only some split types among various split types of a plurality of blocks. For example, when the current block is located on the boundary of a picture, the video decoding apparatus 100 may only allow quad splitting among various split types.

If there is no specific partition type mode that can be used in the current block, the video decoding apparatus 100 may implicitly partition the current block until the divided block has a specific partition type mode that can be used in the block.

If the current block located on the boundary of the picture does not have a residual, the image decoding apparatus 100 may determine not to further divide the current block. To make this possible, the video decoding device 100 may perform the following operations.

When the current block is located on the border of a picture, the video decoding apparatus 100 may obtain a flag from the bitstream that indicates whether implicit splitting of the current block is allowed. If the value of the flag is equal to 0, the video decoding apparatus 100 may determine that implicit segmentation for the current block is not allowed. In this case, the video decoding apparatus 100 may obtain information about the division type mode of the current block from the bitstream and determine the division type mode of the current block based on the obtained information. If the value of the flag is equal to 1, the video decoding apparatus 100 may determine that implicit segmentation for the current block is allowed. In this case, the image decoding apparatus 100 may perform implicit segmentation on the current block.

When the current block is located on a picture boundary, the video decoding apparatus 100 may obtain a flag indicating that the current block does not have a residual from the bitstream. If the value of the flag is equal to 0, the video decoding apparatus 100 may perform implicit segmentation on the current block. If the value of the flag is equal to 1, the video decoding apparatus 100 may determine to perform a skip mode decoding process on the current block.

When the current maximum coding unit is located on the border of a picture, the video decoding apparatus 100 may obtain a maximum coding unit level flag from the bitstream that indicates whether implicit segmentation for the maximum coding unit is allowed.

If the value of the flag is 0, the video decoding device 100 may determine that implicit segmentation for the maximum coding unit is not allowed. The video decoding device 100 is

If the value of the flag is 1, it is determined that implicit splitting for the maximum coding unit is allowed, and an implicit splitting process for the maximum coding unit can be performed.

When the current largest coding unit is located on a picture boundary, the video decoding device 100 may obtain a flag indicating that the current largest coding unit does not have a residual from the bitstream. If the value of the flag is equal to 0, the video decoding device 100 may perform implicit segmentation on the current maximum coding unit. If the value of the flag is equal to 1, the video decoding device 100 may determine to perform a skip mode decoding process for the current maximum coding unit.

When the current block is located at the boundary of a picture, the video decoding apparatus 100 may implicitly determine the division type mode of the current block. For example, the image decoding apparatus 100 may determine one split type mode among a plurality of specific split type modes based on a boundary condition. When the current block is located on the right border of the picture, the video decoding apparatus 100 may obtain a flag indicating one of binary division and quad division from the bitstream.

When the current maximum coding unit is located on a picture boundary, the video decoding apparatus 100 may obtain information about the segmentation mode used for the current maximum coding unit from the bitstream.

When the current block is located on a picture boundary, the video decoding apparatus 100 may determine the division type mode of the current block based on the ratio of the area within the picture. For example, the image decoding apparatus 100 may determine the division mode of the current block based on the ratio of the height and width of the block area in the picture. If the current block is located on the left boundary or the right boundary, and the ratio of the width and height of the current block is greater than N, the video decoding device 100 may determine the division type of the current block to be quad division. Otherwise, the video decoding apparatus 100 may determine the division type of the current block to be binary division.

If the ratio of the width and height of the current block is not equal to an integer value, the video decoding apparatus 100 may determine the division type of the current block as quad division or determine the division type of the current block as binary division.

Alternatively, the image decoding apparatus 100 can always obtain information about the division type mode of the current block from the bitstream, regardless of whether the current block is located on the boundary of the picture. When the current block is located on the border of a picture, the video decoding device 100 performs entropy decoding by allocating a context-adaptive binary arithmetic coding (CABAC) context that is different from the context of blocks that are not located on the border of the picture. You can decide. The image decoding apparatus 100 may determine to perform entropy decoding using a CABAC context based on a boundary condition.

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

In step S105, the image decoding apparatus 100 may hierarchically divide the luma image based on the division type mode of the block included in the luma image of the current image and determine a plurality of coding units in the luma image. The division type mode may be a mode based on at least one of the division direction and division type of the block. The split type may represent at least one of binary split, tri split, and quad split.

In step S110, the image decoding device 100 may hierarchically segment the chroma image based on the segmentation mode of blocks within the chroma image of the current image and determine a plurality of coding units within the chroma image. The image decoding device 100 is smaller than or equal to the size or area of one chroma block among a plurality of chroma blocks that can be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image. In this case, at least one coding unit included in the current chroma block may be determined without allowing division of the current chroma block based on the division type mode of the current chroma block.

In step S115, the image decoding device 100 may decode the current image based on a plurality of coding units in the luma image and a plurality of coding units in the chroma image.

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

The image decoding unit 6000 according to various embodiments performs tasks required to encode image data in the image decoding unit 110 of the image decoding device 100.

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

The intra prediction unit 6400 performs intra prediction for each block. The inter prediction unit 6350 performs inter prediction using the reference image obtained from the reconstructed picture buffer 6300 for each block. By adding the prediction data and residue data for each block generated in the intra prediction unit 6400 or the inter prediction unit 6350, data in the spatial domain for the block of the current image 6050 is restored, and the deblocking unit ( 6450) and the SAO performing unit 6500 may perform loop filtering on data in the restored spatial domain and output the filtered restored image 6600. Additionally, restored images stored in the restored picture buffer 6300 may be output as reference images.

In order to decode image data in the image decoding device 100, step-by-step operations of the image decoder 6000 according to various embodiments may be performed block by block.

FIG. 2A shows a block diagram of an image encoding device according to various embodiments.

The image encoding device 150 according to various embodiments may include a coding unit determination unit 155 and an image encoding unit 160.

The coding unit determination unit 155 and the image encoding unit 160 may include at least one processor. Additionally, the coding unit determiner 155 and the image encoder 160 may include a memory that stores instructions to be performed by at least one processor. The image encoder 160 may be implemented as hardware separate from the coding unit determination unit 155, or may include the coding unit determination unit 155.

The coding unit determiner 155 may determine a plurality of coding units in the luma image by hierarchically dividing the luma image based on the division type mode of blocks included in the luma image of the current image.

The coding unit determination unit 155 may determine a plurality of coding units in the chroma image by hierarchically dividing the chroma image based on the division type mode of blocks in the chroma image of the current image. The coding unit determiner 155 determines the size or area of one chroma block among a plurality of chroma blocks that can be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image by a predetermined amount. You can determine whether it is less than or equal to the size or area. According to the result of the above determination, the coding unit determination unit 155 may determine that division of the current chroma block is not permitted based on the division type mode of the current chroma block.

The coding unit determination unit 155 may determine at least one coding unit included in the current chroma block based on one of the split type modes of the current block that are allowed except for the split type mode determined not to be allowed. . If there is no partition type mode of the current block that is allowed, the coding unit determination unit 155 may determine the current chroma block as the coding unit without further partitioning.

The coding unit determiner 155 determines the size or area of one chroma block among a plurality of chroma blocks that can be generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image by a predetermined amount. If it is determined that it is less than or equal to the size or width, it may be determined that division of the current chroma block is not allowed based on the division type mode of the current chroma block. At this time, the predetermined size may be one of 4x2, 2x4, and 2x2. Additionally, the predetermined width may be one of 8 and 4.

The coding unit determiner 155 selects one of a plurality of blocks that can be generated by dividing the current chroma block in the chroma image according to whether conditions based on the size or area of the current chroma block and the division type mode of the current chroma block are satisfied. It can be determined whether the size or area of one chroma block is smaller than or equal to a predetermined size or area. At this time, the condition based on the size or width of the current chroma block and the division type mode of the current block is a condition for whether the width or height of the current chroma block is less than or equal to 4 if the division type of the current chroma block is quad division. It can be. When the partition type of the current chroma block indicates quad partition, the coding unit determination unit 155 may determine that partition based on quad partition is not allowed if the size or width of the current chroma block is less than or equal to 4. That is, if the height or width of the current chroma block is less than or equal to 4, the height or width of one chroma block among a plurality of chroma blocks created by quad-dividing the current chroma block may be less than or equal to 2. Therefore, the size of one chroma block among the plurality of chroma blocks generated by quad-dividing the current chroma block may be 2x2, 4x2, 2x4 (or smaller), and the size of this block is allowed as a coding unit to encode or When decrypting, you may decide not to allow quad-splitting of the current block to improve throughput because this may reduce throughput. The coding unit decision unit 155 may split the current chroma block based on other allowable split types except quad split. If there is no split type allowed in the current chroma block, the coding unit determination unit 155 may determine the current chroma block as the coding unit without further splitting.

The condition based on the size or width of the current chroma block and the division type mode of the current block may be a condition regarding whether the width of the current chroma block is less than or equal to 16 when the division type of the current chroma block indicates binary division. When the division type of the current chroma block indicates binary division, the coding unit determination unit 155 may determine that division based on binary division is not permitted if the area of the current chroma block is less than or equal to 16. That is, when the width of the current chroma block is less than or equal to 16 (for example, when the size of the current chroma block is less than or equal to 2x8, 8x2, 4x4), multiple chroma blocks are created by binary dividing the current chroma block. The size of one chroma block may be less than or equal to 2x4 or 4x2. When encoding or decoding by allowing the size of such a block as a coding unit, throughput may be reduced, so it may be decided not to allow binary division of the current block in order to improve throughput. The coding unit decision unit 155 may split the current chroma block based on other allowable split types except binary split. If there is no split type allowed in the current chroma block, the coding unit determination unit 155 may determine the current chroma block as the coding unit without further splitting.

The condition based on the size or width of the current chroma block and the division type mode of the current block may be a condition regarding whether the width of the current chroma block is less than or equal to 32 when the division type of the current chroma block indicates trie division. When the division type of the current chroma block indicates trie division, the coding unit determination unit 155 may determine that division based on binary division is not permitted if the area of the current chroma block is less than or equal to 32. That is, if the area of the current chroma block is less than or equal to 32 (for example, if the size of the current chroma block is less than or equal to 4x8, 8x4, 2x16, 16x2), a plurality of The size of one of the chroma blocks may be less than or equal to 2x4 or 4x2. When encoding or decoding by allowing the size of such a block as a coding unit, throughput may be reduced, so it may be decided not to allow tri-division of the current block to improve throughput. The coding unit decision unit 155 may split the current chroma block based on other allowable split types other than trie split. If there is no split type allowed in the current chroma block, the coding unit determination unit 155 may determine the current chroma block as the coding unit without further splitting.

The segmentation mode of blocks in the chroma image of the current image may be independent of the segmentation mode of blocks included in the luma image of the current image, but is not limited to this, and the segmentation mode of blocks in the chroma image of the current image may be independent of the segmentation mode of blocks included in the luma image of the current image. The segmentation type mode of corresponding blocks in the luma image of the current image corresponding to blocks in the image may be dependent on the mode.

That is, the coding unit determiner 155 hierarchically divides the luma image based on the segmentation mode of blocks included in the luma image of the current image to determine a plurality of coding units in the luma image, and determines a plurality of coding units in the luma image. A chroma image may be hierarchically divided based on the segmentation mode of blocks and the segmentation mode of blocks included in the same chroma image to determine a plurality of coding units in the chroma image. At this time, the coding unit determiner 155 may determine the size of a block in the chroma image based on the chroma subsampling method of the current image and the size of the corresponding block of the luma image. For example, if the chroma subsampling method is YUV 4:2:0 and the size of the corresponding block of the luma image is 16x16, the size of the block in the chroma image may be determined to be 8x8.

The coding unit determiner 155 determines that the size of one block among the plurality of blocks divided from the current chroma block in the chroma image is 2xN (N is an integer greater than or equal to 2) based on the division type mode of the current chroma block in the chroma image. ) or less than or equal to Nx2, it may be determined that division of the current chroma block is not permitted based on the division type mode of the current chroma block. The coding unit determination unit 155 may determine at least one coding unit included in the current chroma block based on the remaining allowable split types excluding the impermissible split types.

The image encoder 160 may encode the current image based on a plurality of coding units in the luma image and a plurality of coding units in the chroma image.

Each luma block divided in each inter slice or picture may have a different prediction mode. For example, each luma block may have an inter or intra prediction mode. In this case, the image encoding device 150 may determine the prediction mode of the corresponding chroma block as follows. If the current slice or picture is an inter slice or picture, and the ratio of the area of the luma block with the intra prediction mode to the area of the luma block is greater than a predetermined value, the video encoding device 150 sets the prediction mode of the chroma block to the intra prediction mode. The decision can be made in prediction mode.

When the current slice or picture is an inter slice or picture, if the ratio of the area of the luma block with the inter prediction mode among the areas of the luma block is greater than a predetermined value, the video encoding device 150 sets the prediction mode of the chroma block to inter prediction mode. The decision can be made in prediction mode.

*When a luma block of a specific size is divided, the video encoding device 150 encodes information about the prediction mode of the corresponding chroma block and generates a bitstream including information about the prediction mode of the encoded chroma block. You can.

The image encoding device 150 may determine the prediction mode of the luma corresponding block corresponding to a specific position of the chroma block as the prediction mode of the chroma block. For example, the specific location may be an upper left location, a center location, a lower left location, an upper location, a lower right location, etc. At this time, the specific location may be a predefined location, but is not limited to this, and the video encoding device 150 may encode information about the specific location and generate a bitstream including the encoded information about the specific location. there is.

In order to improve throughput, the image encoding device 150 may perform the following operations when the size of the current block is smaller than or equal to a specific size or when the width of the current block is smaller than or equal to a specific value.

The image encoding device 150 may transform the current block using a transformation method other than a transformation method such as DCT (Discrete Cosine Transform). For example, if the size of the current block is smaller than 4x4, the image encoding device 150 may transform the current block using the Hadamard transform.

The image encoding device 150 may decide to omit transformation for the current block. For example, the video encoding device 150 may encode a transform skip flag for the current block and generate a bitstream including the encoded flag, but the size of the current block may be smaller than or equal to a specific size. If the width of the current block is less than or equal to a specific value, it is determined to skip transformation for the current block, and the transformation skip flag for the current block may not be encoded.

Additionally, the image encoding device 150 may determine that division of the block is not permitted when the size of the block is less than or equal to a specific size or area. For example, if the size of the current block is 8x8, the image encoding device 150 may determine that division of the current block is not allowed. Additionally, for example, if the width of the current block is 64, the image encoding device 150 may determine that division of the current block is not allowed.

When the current slice or picture is an inter slice or picture, the video encoding device 150 may perform the following operation because the probability of splitting a block may be lower than the probability of skipping the block.

The video encoding device 150 may encode skip information of the current block before segmentation information of the current block.

Additionally, when the video encoding device 150 determines that the maximum coding unit does not have residual information, it determines not to encode syntax elements related to the residual, and sets a flag indicating that the maximum coding unit does not have residual information. It is possible to encode and generate a bitstream including the encoded flag.

The video encoding device 150 may determine that asymmetric binary segmentation is not allowed when the current slice or picture is an inter slice or picture.

The image encoding device 150 may split the current block when the current block is located on the boundary of a picture. At this time, the image encoding device 150 may not encode information about the division type mode of the current block.

For example, when the current block is located on the boundary of a picture, the image encoding device 150 may quad-split the current block without separately encoding split type mode information. At this time, quad division may be performed recursively until the divided block is not located on the border of the picture. However, if there is a predetermined division depth, the block may be divided up to that depth.

Meanwhile, when the current block is located on the boundary of a picture, the image encoding device 150 can split the current block without separately encoding the split type mode information for the current block, but based on various split types and split directions. The current block can be split. In this case, the image encoding device 150 may determine the division type and division direction of the current block based on the boundary condition of the block. At this time, the divided block may be divided recursively until it is not located on the border of the picture. However, if there is a predetermined division depth, the block may be divided up to that depth.

For example, when the current block is located on the lower border of the picture, the video encoding device 150 determines the division direction of the current block to be horizontal, determines the division type as binary division, and determines the division direction of the current block. And based on the division type, the current block can be binary divided in the horizontal direction.

When the current block is located on the right border of the picture, the video encoding device 150 determines the division direction of the current block to be vertical, determines the division type of the current block as binary division, and determines the division direction and direction of the current block. Based on the split type, the current block can be binary split in the vertical direction.

When the current block is located on the lower right border of the picture, the image encoding device 150 may determine the partition type of the current block to be quad partition and quad partition the current block based on the partition type of the current block.

As the split types or directions of allowable blocks become more diverse, the complexity increases exponentially, and the video encoding device 150 limits some of the various split types or directions to reduce complexity. can do.

For example, the image encoding device 150 may limit the division depth of binary division. The image encoding device 150 may limit the ratio of allowable blocks or the size of allowable blocks.

The video encoding device 150 may segment a block using only the segmentation mode that satisfies the above-mentioned restriction conditions and may not separately encode information regarding the segmentation mode.

When the current block is located on the boundary of a picture, the image encoding device 150 may only allow some split types among various split types of a plurality of blocks. For example, when the current block is located on the border of a picture, the image encoding device 150 may only allow quad splitting among various split types.

If there is no specific partition type mode that can be used in the current block, the image encoding device 150 may implicitly partition the current block until the divided block has a specific partition type mode that can be used in the block.

If the current block located on the border of the picture does not have a residual, the image encoding device 150 may determine not to further divide the current block. To make this possible, the image encoding device 150 may perform the following operations.

When the current block is located on the boundary of a picture, the video encoding device 150 may encode a flag indicating whether implicit splitting of the current block is allowed. If the video encoding device 150 determines that implicit segmentation for the current block is not allowed, the video encoding device 150 may encode the flag value as 0. In this case, the image encoding device 150 may encode information about the division type mode of the current block and generate a bitstream including information about the encoded division type mode of the current block.

If the video encoding device 150 determines that implicit segmentation of the current block is allowed, the video encoding device 150 may encode the flag value as 1.

When located on a picture boundary, the image encoding device 150 may encode a flag indicating that the current block does not have a residual and generate a bitstream including the encoded flag.

When performing implicit segmentation on the current block, the image encoding device 150 may encode the flag value as 0. When performing a skip mode encoding process on the current block, the image encoding device 150 may encode the flag value as 1.

When the current maximum coding unit is located on the border of a picture, the video encoding device 150 may encode a flag at the maximum coding unit level indicating whether implicit segmentation for the maximum coding unit is allowed.

When the video encoding device 150 determines that implicit segmentation for the maximum coding unit is not permitted, the value of the flag may be encoded as 0.

When performing an implicit segmentation process for the maximum coding unit, the video encoding device 150 may encode the value of the flag as 1.

When the current largest coding unit is located on a picture boundary, the image encoding device 150 may encode a flag indicating that the current largest coding unit does not have a residual. When performing implicit segmentation on the current maximum coding unit, the video encoding device 150 may encode the value of the flag equal to 0. When the video encoding device 150 determines to perform a skip mode encoding process on the current maximum coding unit, the video encoding device 150 may encode the flag value to be equal to 1.

When the current block is located at the boundary of a picture, the image encoding device 150 may implicitly determine the division type mode of the current block. For example, the image encoding device 150 may determine one segment mode among a plurality of specific segment mode modes based on a boundary condition. When the current block is located on the right border of the picture, the image encoding device 150 may encode a flag indicating one of binary division and quad division.

When the current largest coding unit is located on a picture boundary, the image encoding device 150 encodes information about the segmentation mode used for the current largest coding unit, and encodes a bit containing information about the encoded segmentation mode. Streams can be created.

When the current block is located on a picture boundary, the video encoding device 150 may determine the division type mode of the current block based on the ratio of the area within the picture. For example, the division type mode of the current block can be determined based on the ratio of the height and width of the block area in the picture. If the current block is located on the left boundary or the right boundary, and the ratio of the width and height of the current block is greater than N, the image encoding device 150 may determine the division type of the current block to be quad division. Otherwise, the image encoding device 150 may determine the division type of the current block to be binary division.

If the ratio of the width and height of the current block is not equal to an integer value, the image encoding device 150 may determine the division type of the current block to be quad division, or may determine the division type of the current block to be binary division.

Alternatively, the image encoding device 150 may encode information about the division type mode of the current block, regardless of whether the current block is located on the boundary of the picture.

When the current block is located on the border of a picture, the image encoding device 150 may perform entropy coding by allocating a context-adaptive binary arithmetic coding (CABAC) context that is different from the context of blocks that are not located on the border of the picture. . The image encoding device 150 may perform entropy encoding using a CABAC context based on boundary conditions.

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

In step S155, the image encoding device 150 may hierarchically divide the luma image based on the segmentation mode of blocks included in the luma image of the current image and determine a plurality of coding units in the luma image.

In step S160, the image encoding device 150 may determine a plurality of coding units in the chroma image by hierarchically dividing the chroma image based on the segmentation mode of blocks in the chroma image of the current image. The image encoding device 150 determines that the size or area of one chroma block among a plurality of chroma blocks generated by dividing the current chroma block in the chroma image based on the division type mode of the current chroma block in the chroma image is a predetermined size or area. If it is less than or equal to, division of the current chroma block based on the division type mode of the current chroma block is not permitted, and at least one coding unit included in the current chroma block may be determined.

In step S165, the image encoding device 150 may encode the current image based on a plurality of coding units in the luma image and a plurality of coding units in the chroma image.

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

The image encoder 7000 according to various embodiments performs the tasks required to encode image data in the image encoder 160 of the video encoding device 150.

That is, the intra prediction unit 7200 performs intra prediction for each block of the current image 7050, and the inter prediction unit 7150 performs intra prediction on the current image 7050 and the reference image obtained from the reconstructed picture buffer 7100 for each block. Inter prediction is performed using

Residue data is generated by subtracting the prediction data for each block output from the intra prediction unit 7200 or the inter prediction unit 7150 from the data for the block to be encoded in the current image 7050, and the conversion unit 7250 And the quantization unit 7300 may perform transformation and quantization on the residual data and output quantized transformation coefficients for each block. The inverse quantization unit 7450 and the inverse transform unit 7500 can restore residual data in the spatial domain by performing inverse quantization and inverse transformation on the quantized transform coefficients. The restored residual data in the spatial domain is added to the prediction data for each block output from the intra prediction unit 7200 or the inter prediction unit 7150, thereby restoring spatial domain data for the blocks of the current image 7050. . The deblocking unit 7550 and the SAO performing unit perform in-loop filtering on data in the restored spatial domain and generate a filtered restored image. The generated restored image is stored in the restored picture buffer 7100. Reconstructed images stored in the reconstructed picture buffer 7100 can be used as reference images for inter prediction of other images. The entropy encoding unit 7350 entropy encodes the quantized transform coefficient, and the entropy encoded coefficient may be output as a bitstream 7400.

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

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

The video can be divided into maximum coding units. The size of the maximum coding unit can 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 to this. Additionally, the maximum coding unit may be hierarchically divided into coding units based on information about the split type mode obtained from the bitstream. Information about the division type mode may include at least one of information indicating whether to divide, division direction information, and division type information. Information indicating whether to split indicates whether to split the coding unit. Division direction information indicates division in either the horizontal or vertical direction. Split type information indicates that the coding unit is split into one of binary split, tri split (or triple split), or quad split.

For convenience of explanation, the present disclosure divides information about the split type mode into information indicating whether to split, split direction information, and split type information, but is not limited thereto. The video decoding apparatus 100 can obtain information about the segmentation mode from the bitstream as one empty string. The video decoding apparatus 100 may determine whether to split a coding unit, a splitting direction, and a splitting type based on one empty string.

The coding unit may be smaller than or equal to the maximum coding unit. For example, if information about the split type mode indicates that it is not split, the coding unit has the same size as the maximum coding unit. If the information about the split mode indicates splitting, the maximum coding unit may be split into coding units of lower depth. Additionally, if the information about the split form mode for the coding unit of the lower depth indicates splitting, the coding unit of the lower depth may be split into coding units of smaller size. However, segmentation of the image is not limited to this, and the maximum coding unit and coding unit may not be distinguished. Division of the coding unit will be described in more detail in FIGS. 3 to 16.

Additionally, the coding unit can be divided into prediction units for video prediction. The prediction unit may be equal to or smaller than the coding unit. Additionally, the coding unit can be divided into conversion units for image conversion. The conversion unit may be equal to or smaller than the encoding unit. The shape and size of the transformation unit and prediction unit may be unrelated. A coding unit may be distinguished from a prediction unit and a transformation unit, but the coding unit, prediction unit, and transformation unit may be the same as each other. Division of prediction units and transformation units may be performed in the same manner as division of coding units. 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 a maximum coding unit, a coding unit, a prediction unit, and a transformation unit. Additionally, the current block or current coding unit is a block currently undergoing decoding or encoding, or a block currently undergoing division. The surrounding block may be a block restored before the current block. Neighboring blocks may be spatially or temporally adjacent to the current block. Surrounding blocks can be located on one of the following: bottom left, left, top left, top, top right, right, and bottom right of the current block.

FIG. 3 illustrates a process in which the video decoding apparatus 100 divides a current coding unit and determines at least one coding unit, according to an embodiment.

Block shapes may include 4Nx4N, 4Nx2N, 2Nx4N, 4NxN, Nx4N, 32NxN, Nx32N, 16NxN, Nx16N, 8NxN or Nx8N. Here, N may be a positive integer. Block shape information is information representing at least one of the shape, direction, width, and height ratio or size of the 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 (that is, when the block shape of the coding unit is 4Nx4N), the video decoding device 100 may determine the block shape information of the coding unit to be square. The video decoding device 100 may determine the shape of the coding unit to be non-square.

If the width and height lengths of the coding unit are different (that is, if the block shape of the coding unit is 4Nx4N, 4Nx2N, 2Nx4N, 4NxN, Nx4N, 32NxN, Nx32N, 16NxN, Nx16N, 8NxN, or Nx8N), the video decoding device (100 ) can determine the block shape information of the coding unit to be non-square. When the shape of the coding unit is non-square, the video decoding device 100 sets the ratio of the width and height of the block shape information of the coding unit to 1:2, 2:1, 1:4, 4:1, 1:8. Alternatively, you can decide on at least one of 8:1. Additionally, based on the width and height of the coding unit, the video decoding device 100 may determine whether the coding unit is in the horizontal or vertical direction. Additionally, the video decoding apparatus 100 may determine the size of the coding unit based on at least one of the width length, height length, or area of the coding unit.

According to one embodiment, the video decoding apparatus 100 may determine the form of a coding unit using block shape information, and determine in what form the coding unit is divided using information on the split form mode. In other words, the method of dividing the coding unit indicated by the information about the split type mode can be determined depending on what block type the block type information used by the video decoding apparatus 100 represents.

The video decoding apparatus 100 may obtain information about the segmentation mode from the bitstream. However, it is not limited to this, and the image decoding device 100 and the image encoding device 150 may obtain information about a pre-arranged segmentation type mode based on block type information. The video decoding device 100 may obtain information about a pre-arranged segmentation mode for the maximum coding unit or the minimum coding unit. For example, the video decoding device 100 may determine information about the split type mode for the maximum coding unit as quad split. Additionally, the video decoding device 100 may determine information about the split type mode as “not split” for the minimum coding unit. Specifically, the video decoding device 100 may determine the size of the maximum coding unit to be 256x256. The video decoding device 100 may determine information about the pre-arranged division type mode as quad division. Quad division is a division mode that divides both the width and height of the coding unit into two halves. The video decoding device 100 may obtain a coding unit of size 128x128 from the largest coding unit of size 256x256 based on information about the segmentation mode. Additionally, the video decoding device 100 may determine the size of the minimum coding unit to be 4x4. The video decoding device 100 may obtain information about a segmentation mode indicating “not segmentation” for the minimum coding unit.

According to one embodiment, the video decoding device 100 may use block shape information indicating that the current coding unit is square. For example, the video decoding device 100 may determine whether to split the square coding unit, whether to split it vertically, horizontally, or into four coding units, according to information about the split type mode. Referring to FIG. 3, when the block shape information of the current coding unit 300 indicates a square shape, the decoder 120 divides the current coding unit 300 and The coding unit 310a having the same size may not be divided, or the divided coding units 310b, 310c, 310d, etc. may be determined based on information about the division type mode indicating a predetermined division method.

Referring to FIG. 3, the video decoding device 100 divides the current coding unit 300 in the vertical direction into two coding units 310b based on information about the split type mode indicating vertical splitting according to one embodiment. ) can be determined. The video decoding apparatus 100 may determine two coding units 310c obtained by dividing the current coding unit 300 in the horizontal direction based on information about the division type mode indicating division in the horizontal direction. The video decoding device 100 can determine four coding units 310d obtained by dividing the current coding unit 300 in the vertical and horizontal directions based on information about the division type mode indicating division in the vertical and horizontal directions. there is. According to one embodiment, the video decoding device 100 divides the current coding unit 300 in the vertical direction into three coding units 310e based on split type mode information indicating tri (or ternary) splitting in the vertical direction. can be decided. The video decoding apparatus 100 may determine three coding units 310f obtained by dividing the current coding unit 300 in the horizontal direction based on division type mode information indicating ternary division in the horizontal direction.

However, the division form into which the square coding unit can be divided should not be interpreted as limited to the above-described form, and may include various forms that can be indicated by information about the division mode. Predetermined division forms into which a square coding unit is divided will be described in detail below through various embodiments.

FIG. 4 illustrates a process in which the image decoding apparatus 100 divides a coding unit in a non-square shape and determines at least one coding unit, according to an embodiment.

According to one embodiment, the image decoding apparatus 100 may use block shape information indicating that the current coding unit is in a non-square shape. The image decoding apparatus 100 may determine whether to split the non-square current coding unit or not to split it using a predetermined method according to information about the split type mode. Referring to FIG. 4, when the block shape information of the current coding unit (400 or 450) indicates a non-square shape, the image decoding device 100 performs the current encoding according to information about the segmentation shape mode indicating that it is not segmented. A coding unit (410 or 460) having the same size as the unit (400 or 450) is determined, or a coding unit (420a, 420b, 430a, 430b) is divided based on information about the division mode indicating a predetermined division method. , 430c, 470a, 470b, 480a, 480b, 480c) can be determined. A predetermined division method by which non-square coding units are divided will be described in detail below through various embodiments.

According to one embodiment, the video decoding device 100 may determine the form in which the coding unit is divided using information about the split type mode. In this case, the information about the split type mode includes at least one piece generated by splitting the coding unit. It can indicate the number of coding units. Referring to FIG. 4, when the information about the split type mode indicates that the current coding unit (400 or 450) is divided into two coding units, the video decoding device 100 performs the current encoding based on the information about the split type mode. By dividing the unit 400 or 450, two coding units 420a, 420b, or 470a, 470b included in the current coding unit can be determined.

According to one embodiment, when the image decoding device 100 divides the current coding unit (400 or 450) in a non-square shape based on information about the segmentation mode, the image decoding device 100 divides the current coding unit (400 or 450) into a non-square shape. The current coding unit can be divided by considering the position of the long side of the current coding unit (400 or 450). For example, the video decoding device 100 divides the current coding unit (400 or 450) in a direction that divides the long side of the current coding unit (400 or 450) in consideration of the shape of the current coding unit (400 or 450). Thus, a plurality of coding units can be determined.

According to one embodiment, when the information about the split type mode indicates that the coding unit is split into an odd number of blocks (tri split), the video decoding device 100 includes the current coding unit 400 or 450. An odd number of coding units can be determined. For example, if the information about the split type mode indicates dividing the current coding unit (400 or 450) into three coding units, the video decoding device 100 divides the current coding unit (400 or 450) into three coding units. It can be divided into units (430a, 430b, 430c, 480a, 480b, 480c).

According to one 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 width length is longer than the height length, so the block shape information may be horizontal. When the ratio of width and height is 1:4, the width length is shorter than the height length, so the block shape information may be vertically oriented. The video decoding apparatus 100 may determine to split the current coding unit into an odd number of blocks based on information about the split type mode. Additionally, the image decoding device 100 may determine the division direction of the current coding unit (400 or 450) based on the 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 video decoding device 100 may divide the current coding unit 400 in the horizontal direction to determine coding units 430a, 430b, and 430c. Additionally, when the current coding unit 450 is in the horizontal direction, the video decoding device 100 may divide the current coding unit 450 in the vertical direction to determine coding units 480a, 480b, and 480c.

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

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

FIG. 5 illustrates a process by which the image decoding apparatus 100 splits a coding unit based on at least one of block type information and information about a split type mode, according to an embodiment.

According to one embodiment, the image decoding apparatus 100 determines to divide or not divide the square-shaped first coding unit 500 into coding units based on at least one of block type information and information about the split type mode. You can. According to one embodiment, when the information about the division type mode indicates dividing the first coding unit 500 in the horizontal direction, the video decoding device 100 divides the first coding unit 500 in the horizontal direction 2 Encoding unit 510 can be determined. The first coding unit, second coding unit, and third coding unit used according to one embodiment are terms used to understand the relationship before and after division between coding units. For example, if the first coding unit is split, the second coding unit can be determined, and if the second coding unit is split, the third coding unit can be determined. Hereinafter, the relationship between the first coding unit, the second coding unit, and the third coding unit used may be understood as being in accordance with the above-described characteristics.

According to one embodiment, the image decoding apparatus 100 may determine to split or not split the determined second coding unit 510 into coding units based on at least one of block type information and information about the split type mode. . Referring to FIG. 5, the image decoding apparatus 100 divides the first coding unit 500 based on at least one of block type information and information about the split type mode to divide the first coding unit 500 into a non-square second coding unit ( 510) may be divided into at least one third coding unit 520a, 520b, 520c, 520d, etc., or the second coding unit 510 may not be divided. The image decoding device 100 may acquire at least one of block type information and information about the split type mode, and the image decoding device 100 may acquire at least one of the obtained block type information and information about the split type mode. The first coding unit 500 can be divided into a plurality of second coding units (for example, 510) of various types, and the second coding unit 510 includes block type information and information about the split type mode. The first coding unit 500 may be divided according to the division method based on at least one of the following. According to one embodiment, when the first coding unit 500 is divided into the second coding unit 510 based on at least one of block type information and information about the division type mode for the first coding unit 500. , the second coding unit 510 is also a third coding unit (e.g., 520a, 520b, 520c, 520d) based on at least one of the block type information and the split type mode information for the second coding unit 510. etc.) can be divided into That is, the coding unit may be recursively divided based on at least one of information about the partition type mode and block type information related to each coding unit. Therefore, a square coding unit may be determined from a non-square coding unit, and the square coding unit may be recursively divided to determine a non-square coding unit.

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

According to one embodiment, the video decoding device 100 divides each of the third coding units (520a, 520b, 520c, 520d, etc.) into coding units based on at least one of block type information and information about the split type mode. You can. Additionally, the image decoding apparatus 100 may determine not to split the second coding unit 510 based on at least one of block type information and information about the split type mode. According to one embodiment, the image decoding device 100 may divide the non-square second coding unit 510 into an odd number of third coding units 520b, 520c, and 520d. The video decoding device 100 may place a predetermined limit on a third coding unit among the odd number of third coding units 520b, 520c, and 520d. For example, the video decoding device 100 restricts the coding unit 520c located in the center among the odd number of third coding units 520b, 520c, and 520d to no longer being split, or splits it a settable number of times. It can be limited to:

Referring to FIG. 5, the image decoding device 100 uses a coding unit ( 520c) is no longer divided, is limited to being divided into a predetermined division form (for example, divided into only four coding units or divided into a form corresponding to the split form of the second coding unit 510), or is divided into a predetermined division form. It can be limited to splitting only the number of times (for example, splitting only n times, n>0). However, the above limitation on the coding unit 520c located in the center is only a simple embodiment and should not be interpreted as limited to the above-described embodiments, and the coding unit 520c located in the center is limited to the other coding units 520b and 520d. ) should be interpreted as including various restrictions that can be decoded differently.

According to one embodiment, the video decoding apparatus 100 may obtain at least one of block type information and information about the split type mode used to split the current coding unit from a predetermined position within the current coding unit.

FIG. 6 illustrates a method by which the video decoding apparatus 100 determines a predetermined coding unit among an odd number of coding units, according to an embodiment.

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

According to one embodiment, when the current coding unit is divided into a predetermined number of coding units, the video decoding device 100 may select one coding unit among them. Methods for selecting one of a plurality of coding units may vary, and these methods will be described later through various embodiments below.

According to one embodiment, the video decoding apparatus 100 may divide the current coding unit into a plurality of coding units and determine a coding unit at a predetermined position.

According to one embodiment, the video decoding apparatus 100 may use information indicating the location of each odd number of coding units to determine a coding unit located in the center among the odd number of coding units. Referring to FIG. 6, the video decoding device 100 divides the current coding unit 600 or the current coding unit 650 into odd-numbered coding units 620a, 620b, 620c or odd-numbered coding units 660a, 660b, 660c) can be determined. The video decoding device 100 uses information about the positions of the odd number of coding units 620a, 620b, and 620c or the odd number of coding units 660a, 660b, and 660c to generate the middle coding unit 620b or the middle coding unit. (660b) can be determined. For example, the image decoding device 100 determines the positions of the coding units 620a, 620b, and 620c based on information indicating the positions of predetermined samples included in the coding units 620a, 620b, and 620c, thereby The coding unit 620b located in can be determined. Specifically, the image decoding device 100 encodes the coding units 620a, 620b, and 620c based on information indicating the positions of the samples 630a, 630b, and 630c at the upper left of the coding units 620a, 620b, and 620c. By determining the position of , the coding unit 620b located in the center can be determined.

According to one embodiment, the information indicating the location of the upper left samples 630a, 630b, and 630c included in the coding units 620a, 620b, and 620c, respectively, is within the picture of the coding units 620a, 620b, and 620c. It may contain information about the location or coordinates. According to one embodiment, the information indicating the positions of the upper left samples 630a, 630b, and 630c included in the coding units 620a, 620b, and 620c, respectively, is the coding units 620a included in the current coding unit 600. , 620b, 620c), and this width or height may correspond to information indicating the difference between coordinates within the picture of the coding units 620a, 620b, and 620c. That is, the video decoding device 100 directly uses information about the positions or coordinates of the coding units 620a, 620b, and 620c within the picture, or uses information about the width or height of the coding unit corresponding to the difference value between the coordinates. By using , the coding unit 620b located in the center can be determined.

According to one embodiment, information indicating the location of the sample 630a at the top left of the top coding unit 620a may represent (xa, ya) coordinates, and the sample 530b at the top left of the middle coding unit 620b. ) may represent (xb, yb) coordinates, and information representing the location of the sample 630c at the upper left of the lower coding unit 620c may represent (xc, yc) coordinates. The video decoding apparatus 100 may determine the middle coding unit 620b using the coordinates of the upper left samples 630a, 630b, and 630c 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. The current coding unit 600 can be determined as a coding unit located in the middle of the divided 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 within the picture, and further represent the location of the upper left samples 630a of the upper coding unit 620a. As a reference, the (dxb, dyb) coordinates are information indicating the relative position of the sample 630b at the upper left of the middle coding unit 620b, and the coordinates indicate the relative position of the sample 630c at the upper left of the lower coding unit 620c. Information (dxc, dyc) coordinates can also be used. In addition, the method of determining the coding unit at a predetermined position by using the coordinates of the sample as information indicating the position of the sample included in the coding unit should not be interpreted as limited to the above-described method, and various arithmetic methods that can use the coordinates of the sample should not be used. It must be interpreted in this way.

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

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

The video decoding device 100 provides (xd, yd) coordinates, which are information indicating the location of the sample 670a in the upper left corner of the left coding unit 660a, and the location of the sample 670b in the upper left corner 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 representing the location of the top left sample 670c of the right coding unit 660c. You can decide the width or height of each. The video decoding device 100 uses coordinates (xd, yd), (xe, ye), and (xf, yf), which represent the positions of the coding units 660a, 660b, and 660c, to encode the coding units 660a, 660b. , 660c) Each size can be determined.

According to one embodiment, the video decoding device 100 may determine the width of the left coding unit 660a to be xe-xd. The video decoding device 100 may determine the height of the left coding unit 660a as the height of the current coding unit 650. According to one embodiment, the video decoding device 100 may determine the width of the middle coding unit 660b as xf-xe. The video decoding device 100 may determine the height of the middle coding unit 660b as the height of the current coding unit 600. According to one embodiment, the image decoding device 100 determines the width or height of the right coding unit 660c, the width or height of the current coding unit 650, and the width or height of the left coding unit 660a and the middle coding unit 660b. It can be decided using . The image decoding apparatus 100 may determine a coding unit having a size different from other coding units based on the width and height of the determined coding units 660a, 660b, and 660c. Referring to FIG. 6, the video decoding device 100 may determine the middle coding unit 660b, which has a size different from the size of the left coding unit 660a and the right coding unit 660c, as the coding unit at a predetermined position. However, the process of determining a coding unit having a size different from other coding units by the video decoding device 100 described above is an embodiment of determining a coding unit at a predetermined position using the size of the coding unit determined based on sample coordinates. Therefore, various processes can be used to determine the coding unit at a predetermined position by comparing the size of the coding unit determined according to the predetermined sample coordinates.

However, the location of the sample considered to determine the location of the coding unit should not be interpreted as being limited to the upper left as described above, and information on the location of any sample included in the coding unit may be interpreted as being available.

According to one embodiment, the video decoding device 100 may consider the form of the current coding unit and select a coding unit at a predetermined position among an odd number of coding units determined by dividing the current coding unit. For example, if the current coding unit has a non-square shape where the width is longer than the height, the video decoding device 100 may determine the coding unit at a predetermined position according to the horizontal direction. That is, the video decoding device 100 can determine one of coding units whose positions vary in the horizontal direction and place restrictions on the corresponding coding unit. If the current coding unit has a non-square shape where the height is longer than the width, the video decoding device 100 may determine the coding unit at a predetermined position according to the vertical direction. That is, the video decoding device 100 can determine one of coding units whose positions vary in the vertical direction and place restrictions on the corresponding coding unit.

According to one embodiment, the video decoding apparatus 100 may use information indicating the position of each even number of coding units to determine a coding unit at a predetermined position among the even number of coding units. The video decoding device 100 can determine an even number of coding units by dividing the current coding unit (binary split or bi-split) and determine a coding unit at a predetermined position using information about the positions of the even number of coding units. You can. The specific process for this may be a process corresponding to the process of determining a coding unit at a predetermined position (for example, the center position) among the odd number of coding units described above in FIG. 6, so it will be omitted.

According to one embodiment, when a non-square current coding unit is divided into a plurality of coding units, a predetermined value for the coding unit at a certain position is determined during the division process in order to determine a coding unit at a certain position among the plurality of coding units. information is available. For example, the video decoding device 100 uses the block type information and division type stored in the sample included in the middle coding unit during the division process to determine the coding unit located in the middle among the coding units in which the current coding unit is divided into a plurality of pieces. At least one piece of information about the mode is available.

Referring to FIG. 6, the video decoding device 100 divides the current coding unit 600 into a plurality of coding units 620a, 620b, and 620c based on at least one of block type information and information about the split type mode. and the coding unit 620b located in the center among the plurality of coding units 620a, 620b, and 620c can be determined. Furthermore, the image decoding apparatus 100 may determine the coding unit 620b located in the center by considering the location where at least one of the block type information and the information about the split type mode is obtained. That is, at least one of the block type information and information about the split type mode of the current coding unit 600 can be obtained from the sample 640 located in the center of the current coding unit 600, and the block type information and the When the current coding unit 600 is divided into a plurality of coding units 620a, 620b, and 620c based on at least one of the information about the split type mode, the coding unit 620b including the sample 640 is placed in the center. It can be determined by the coding unit located in . However, the information used to determine the coding unit located in the center should not be interpreted as limited to at least one of block type information and information about the split type mode, and various types of information are used in the process of determining the coding unit located in the center. can be used in

According to one embodiment, predetermined information for identifying a coding unit at a predetermined position may be obtained from a predetermined sample included in the coding unit to be determined. Referring to FIG. 6, the video decoding device 100 divides the current coding unit 600 into a coding unit at a predetermined position among a plurality of coding units 620a, 620b, and 620c (e.g., divided into a plurality of pieces). Block shape information obtained from a sample at a predetermined position in the current coding unit 600 (for example, a sample located in the center of the current coding unit 600) to determine the coding unit located in the center among the coding units, and At least one piece of information about the split type mode can be used. That is, the video decoding device 100 can determine the sample at the predetermined position by considering the block shape of the current coding unit 600, and the video decoding device 100 can determine the plurality of samples by dividing the current coding unit 600. Among the coding units 620a, 620b, and 620c, a coding unit 620b containing a sample from which predetermined information (for example, at least one of block type information and information about the split type mode) can be obtained is You can decide to place certain restrictions. Referring to FIG. 6, according to one embodiment, the image decoding device 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 device 100 may determine a sample 640 located in the center of the current coding unit 600. 100 may place certain restrictions on the coding unit 620b including the sample 640 during the decoding process. However, the position of the sample from which predetermined information can be obtained should not be interpreted as limited to the above-mentioned position, but may be interpreted as samples at any position included in the coding unit 620b to be determined for the purpose of limitation.

According to one embodiment, the 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 one embodiment, the block shape information may determine whether the shape of the current coding unit is square or non-square, and determine the location of the sample from which predetermined information can be obtained depending on the shape. For example, the video decoding device 100 uses at least one of information about the width and height of the current coding unit to divide at least one of the width and height of the current coding unit into half. The sample may be determined as a sample from which predetermined information can be obtained. For another example, when the block shape information related to the current coding unit indicates that the block shape is in a non-square form, the image decoding device 100 selects one of the samples adjacent to the boundary dividing the long side of the current coding unit in half. It can be determined from a sample from which information can be obtained.

According to one embodiment, when the current coding unit is split into a plurality of coding units, the video decoding device 100 uses block type information and split type mode to determine a coding unit at a predetermined position among the plurality of coding units. At least one of the information is available. According to one embodiment, the image decoding device 100 may obtain at least one of block type information and information about the split type mode from a sample at a predetermined position included in a coding unit, and the image decoding device 100 may obtain the currently encoded information. A plurality of coding units generated by splitting the units can be split using at least one of information about the split type mode and block type information obtained from samples at predetermined positions included in each of the plurality of coding units. That is, the coding unit may be recursively divided using at least one of block type information and information about the division type mode obtained from samples at a predetermined position included in each coding unit. Since the recursive division process of the coding unit has been described in detail with reference to FIG. 5, detailed description will be omitted.

According to one embodiment, the video decoding apparatus 100 may divide the current coding unit to determine at least one coding unit, and determine the order in which the at least one coding unit is decoded by dividing the current coding unit into a predetermined block (e.g., the current coding unit ) can be decided based on

FIG. 7 illustrates the order in which the plurality of coding units are processed when the video decoding apparatus 100 divides the current coding unit to determine a plurality of coding units, according to an embodiment.

According to one embodiment, the image decoding device 100 divides the first coding unit 700 in the vertical direction according to information about the block type information and the split type mode to determine the second coding units 710a and 710b. 1 The second coding unit 730a, 730b is determined by dividing the coding unit 700 in the horizontal direction, or the second coding unit 750a, 750b, 750c is determined by dividing the first coding unit 700 in the vertical and horizontal directions. , 750d) can be determined.

Referring to FIG. 7, the image decoding device 100 may determine the order in which the second coding units 710a and 710b, which are determined by splitting the first coding unit 700 in the vertical direction, are processed 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. The video decoding device 100 divides the first coding unit 700 into vertical and horizontal directions and divides the second coding units 750a, 750b, 750c, and 750d into the second coding units 750a, 750b, 750c, and 750d after the coding units located in one row are processed. It can be determined according to a predetermined order in which coding units located in the next row are processed (for example, raster scan order or z scan order 750e, etc.).

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

According to one embodiment, the video decoding device 100 may divide the second coding unit 710a on the left side in the horizontal direction into third coding units 720a and 720b, and divide the second coding unit 710a on the right side into third coding units 720a and 720b. ) may not be divided.

According to one embodiment, the processing order of coding units may be determined based on the division process of the coding units. In other words, the processing order of the divided coding units can be determined based on the processing order of the coding units immediately before being split. The image decoding device 100 may determine the order in which the third coding units 720a and 720b, which are determined by dividing the second coding unit 710a on the left, are processed independently of the second coding unit 710b on the right. Since the second coding unit 710a on the left is divided in the horizontal direction to determine the third coding units 720a and 720b, the third coding units 720a and 720b can be processed in the vertical direction 720c. In addition, 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, so the third coding unit included in the second coding unit 710a on the left After 720a and 720b are processed in the vertical direction 720c, the right coding unit 710b may be processed. Since the above description is intended to explain the process in which the processing order of each coding unit is determined according to the coding unit before division, it should not be interpreted as limited to the above-described embodiment, and the coding units determined by being divided into various forms are determined in a predetermined manner. It should be interpreted as being used in a variety of ways that can be processed independently in order.

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

According to one embodiment, the image decoding apparatus 100 may determine that the current coding unit is divided into an odd number of coding units based on the obtained block type information and information about the split type mode. Referring to FIG. 8, the square-shaped first coding unit 800 can be divided into non-square-shaped second coding units 810a and 810b, and the second coding units 810a and 810b are each independently It can be divided into 3 coding units (820a, 820b, 820c, 820d, 820e). According to one embodiment, the image decoding device 100 may divide the left coding unit 810a among the second coding units in the horizontal direction to determine a plurality of third coding units 820a and 820b, and divide the left coding unit 810a into a plurality of third coding units 820a and 820b. ) can be divided into an odd number of third coding units (820c, 820d, 820e).

According to one embodiment, the video decoding device 100 determines whether the third coding units 820a, 820b, 820c, 820d, and 820e can be processed in a predetermined order and determines whether there are odd-numbered coding units. You can decide. Referring to FIG. 8, the image decoding device 100 may recursively divide the first coding unit 800 to determine third coding units 820a, 820b, 820c, 820d, and 820e. The image decoding device 100 generates a first coding unit 800, a second coding unit 810a, 810b, or a third coding unit 820a, 820b based on at least one of block type information and information about the split type mode. , 820c, 820d, 820e) can be determined whether they are divided into an odd number of coding units. For example, the coding unit located on the right of the second coding units 810a and 810b 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 (e.g., z-scan order 830), and the image decoding device ( 100) may determine whether the third coding units 820c, 820d, and 820e, which are determined by dividing the right second coding unit 810b into an odd number, satisfy the condition that they can be processed according to the predetermined order.

According to one embodiment, the video decoding device 100 satisfies the condition that the third coding units 820a, 820b, 820c, 820d, and 820e included in the first coding unit 800 can be processed in a predetermined order. The condition may include whether at least one of the width and height of the second coding units 810a and 810b is divided in half according to the boundary of the third coding units 820a, 820b, 820c, 820d and 820e. It is related. For example, the third coding units 820a and 820b determined by dividing the height of the non-square left second coding unit 810a in half may satisfy the condition. The boundaries of the third coding units (820c, 820d, 820e) determined by dividing the right second coding unit (810b) into three coding units cannot 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. If this condition is not satisfied, the video decoding device 100 may determine that the scan order is disconnected, and based on the determination result, determine that the right second coding unit 810b is divided into an odd number of coding units. According to one embodiment, when the video decoding device 100 is divided into an odd number of coding units, a predetermined restriction may be placed on the coding unit at a predetermined position among the divided coding units, and various restrictions may be placed on the content of the restriction or the predetermined position. Since it has been described in detail through examples, detailed description will be omitted.

FIG. 9 illustrates a process in which the video decoding apparatus 100 divides the first coding unit 900 and determines at least one coding unit, according to an embodiment.

According to one embodiment, the video decoding apparatus 100 may split the first coding unit 900 based on at least one of block type information and information about the split type mode acquired through a receiver (not shown). The square-shaped first coding unit 900 may be divided into four square-shaped coding units or may be divided into a plurality of non-square-shaped coding units. For example, referring to FIG. 9, when the block shape information indicates that the first coding unit 900 is a square and the information on the partition type mode indicates that the first coding unit 900 is divided into non-square coding units, the image decoding device 100 1 coding unit 900 can be divided into a plurality of non-square coding units. Specifically, when the information about the division type mode indicates that an odd number of coding units is determined by dividing the first coding unit 900 in the horizontal or vertical direction, the video decoding device 100 divides the first coding unit 900 into a square shape. The unit 900 may be divided into second coding units 910a, 910b, and 910c determined by being split in the vertical direction or into second coding units 920a, 920b, and 920c determined by being split in the horizontal direction as an odd number of coding units. .

According to one embodiment, the image decoding device 100 is configured to process the second coding units 910a, 910b, 910c, 920a, 920b, and 920c included in the first coding unit 900 in a predetermined order. It can be determined whether is satisfied, and the condition is whether at least one of the width and height of the first coding unit 900 is divided in half according to the boundary of the second coding unit 910a, 910b, 910c, 920a, 920b, 920c. It is related to whether Referring to FIG. 9, the boundaries of the second coding units 910a, 910b, and 910c, which are determined by dividing the square-shaped first coding unit 900 in the vertical direction, divide the width of the first coding unit 900 in half. Since this is not possible, it may be determined that the first coding unit 900 does not satisfy the condition for being processed in a predetermined order. In addition, the boundaries of the second coding units 920a, 920b, and 920c, which are determined by dividing the square-shaped first coding unit 900 in the horizontal direction, do not split the width of the first coding unit 900 in half, so 1 Encoding unit 900 may be determined to not satisfy the conditions for being processed in a predetermined order. If this condition is not satisfied, the video decoding device 100 may determine that the scan order is disconnected, and based on the determination result, determine that the first coding unit 900 is divided into an odd number of coding units. According to one embodiment, when the video decoding device 100 is divided into an odd number of coding units, a predetermined restriction may be placed on the coding unit at a predetermined position among the divided coding units, and various restrictions may be placed on the content of the restriction or the predetermined position. Since it has been described in detail through examples, detailed description will be omitted.

According to one embodiment, the video decoding device 100 may divide the first coding unit to determine various types of coding units.

Referring to FIG. 9, the image decoding device 100 may divide the square-shaped first coding unit 900 and the non-square-shaped first coding unit 930 or 950 into coding units of various shapes. .

FIG. 10 shows, according to one embodiment, when the video decoding device 100 determines that the second coding unit of a non-square shape by dividing the first coding unit 1000 satisfies a predetermined condition, the second coding unit will be divided. It shows that the possible forms are limited.

According to one embodiment, the video decoding device 100 generates a square-shaped first coding unit 1000 based on at least one of block shape information and information about the segmentation mode acquired through a receiver (not shown). It may be decided to divide into square second coding units 1010a, 1010b, 1020a, and 1020b. The second coding units 1010a, 1010b, 1020a, and 1020b may be divided independently. Accordingly, the image decoding device 100 divides or does not divide the second coding units 1010a, 1010b, 1020a, and 1020b into a plurality of coding units based on at least one of block type information and information about the split type mode related to each of the second coding units 1010a, 1010b, 1020a, and 1020b. You can decide what not to do. According to one embodiment, the image decoding device 100 divides the non-square left second coding unit 1010a, which is determined by dividing the first coding unit 1000 in the vertical direction, in the horizontal direction to create a third coding unit ( 1012a, 1012b) can be determined. However, when the video decoding device 100 divides the left second coding unit 1010a in the horizontal direction, the right second coding unit 1010b is divided in the horizontal direction in the same direction as the left second coding unit 1010a. It can be restricted so that it cannot be divided. If the right second coding unit 1010b is divided 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 divided in the horizontal direction, respectively. By being independently divided, the third coding units 1012a, 1012b, 1014a, and 1014b can be determined. However, this means that the image decoding device 100 divides the first coding unit 1000 into four square second coding units 1030a, 1030b, 1030c, and 1030d based on at least one of block type information and information about the split type mode. ), and this may be inefficient in terms of video decoding.

According to one embodiment, the image decoding device 100 divides the first coding unit 1000 in the horizontal direction and divides the non-square second coding unit 1020a or 1020b in the vertical direction to form a third coding unit. (1022a, 1022b, 1024a, 1024b) can be determined. However, when the video decoding device 100 divides one of the second coding units (e.g., the upper second coding unit 1020a) in the vertical direction, the other second coding unit (e.g., the lower second coding unit 1020a) is divided according to the above-mentioned reason. The coding unit 1020b may be restricted so that it cannot be divided in the same vertical direction as the upper second coding unit 1020a.

FIG. 11 illustrates a process by which the image decoding apparatus 100 splits a square-shaped coding unit when information about the split mode cannot indicate division into four square-shaped coding units, according to an embodiment. .

According to one embodiment, the image decoding apparatus 100 divides the first coding unit 1100 based on at least one of block type information and information about the split type mode to generate second coding units 1110a, 1110b, 1120a, and 1120b. etc.) can be determined. Information about the split form mode may include information about various forms into which the coding unit can be split, but there are cases where the information about the various forms cannot include information for splitting the coding unit into four square-shaped coding units. According to the information about this division mode, the image decoding device 100 cannot divide the square-shaped first coding unit 1100 into four square-shaped second coding units 1130a, 1130b, 1130c, and 1130d. . Based on information about the segmentation mode, the image decoding device 100 may determine a non-square second coding unit (1110a, 1110b, 1120a, 1120b, etc.).

According to one embodiment, the video decoding device 100 may independently divide the second coding units (1110a, 1110b, 1120a, 1120b, etc.) of a non-square shape. Through a recursive method, each of the second coding units (1110a, 1110b, 1120a, 1120b, etc.) may be divided in a predetermined order, which is based on at least one of block type information and information about the division type mode. It may be a division method corresponding to the method by which the unit 1100 is divided.

For example, the image decoding device 100 may determine square-shaped third coding units 1112a and 1112b by dividing the left second coding unit 1110a in the horizontal direction, and the right second coding unit 1110b It can be divided in the horizontal direction to determine square-shaped third coding units 1114a and 1114b. Furthermore, the image decoding device 100 may divide both the left second coding unit 1110a and the right second coding unit 1110b in the horizontal direction to determine square-shaped third coding units 1116a, 1116b, 1116c, and 1116d. there is. In this case, the coding unit may be determined in the same form as when the first coding unit 1100 is divided into four square second coding units 1130a, 1130b, 1130c, and 1130d.

For another example, the video decoding device 100 may divide the upper second coding unit 1120a in the vertical direction to determine square-shaped third coding units 1122a and 1122b, and determine the lower second coding unit 1120b. ) can be divided in the vertical direction to determine square-shaped third coding units 1124a and 1124b. Furthermore, the image decoding device 100 may divide both the upper second coding unit 1120a and the lower second coding unit 1120b in the vertical direction to determine square-shaped third coding units 1126a, 1126b, 1126a, and 1126b. there is. In this case, the coding unit may be determined in the same form as when the first coding unit 1100 is divided into four square second coding units 1130a, 1130b, 1130c, and 1130d.

FIG. 12 illustrates that the processing order between a plurality of coding units may vary depending on the division process of the coding unit, according to one embodiment.

According to one embodiment, the image decoding apparatus 100 may split the first coding unit 1200 based on block type information and information about the split type mode. When the block shape information indicates a square shape and the information about the split form mode indicates that the first coding unit 1200 is split in at least one of the horizontal and vertical directions, the image decoding device 100 performs the first encoding. The unit 1200 may be divided to determine a second coding unit (eg, 1210a, 1210b, 1220a, 1220b, etc.). Referring to FIG. 12, the non-square second coding units 1210a, 1210b, 1220a, and 1220b, which are determined by dividing the first coding unit 1200 only in the horizontal or vertical direction, have block shape information and split shape mode for each. Can be divided independently based on information about. For example, the video decoding device 100 divides the second coding units 1210a and 1210b generated by dividing the first coding unit 1200 in the vertical direction, respectively, in the horizontal direction to create third coding units 1216a and 1216b. 1216c and 1216d) can be determined, and the second coding units 1220a and 1220b, which are generated by dividing the first coding unit 1200 in the horizontal direction, are respectively divided in the horizontal direction to produce third coding units 1226a, 1226b, and 1226c. , 1226d) can be determined. Since the division process of the second coding units 1210a, 1210b, 1220a, and 1220b has been described above with reference to FIG. 11, detailed description will be omitted.

According to one embodiment, the video decoding device 100 may process coding units according to a predetermined order. Since the characteristics of processing of coding units according to a predetermined order have been described above with reference to FIG. 7, detailed description will be omitted. Referring to FIG. 12, the video decoding device 100 divides the square-shaped first coding unit 1200 into four square-shaped third coding units (1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d). ) can be determined. According to one embodiment, the video decoding device 100 determines the processing order of the third coding units 1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, and 1226d according to the form in which the first coding unit 1200 is divided. You can decide.

According to one embodiment, the video decoding device 100 divides the second coding units 1210a and 1210b generated by splitting them in the vertical direction, respectively, in the horizontal direction to determine the third coding units 1216a, 1216b, 1216c, and 1216d. The image decoding device 100 first processes the third coding units 1216a and 1216c included in the left second coding unit 1210a in the vertical direction, and then processes the third coding units 1216a and 1216c included in the right second coding unit 1210b. The third coding units 1216a, 1216b, 1216c, and 1216d can be processed according to the order 1217 of processing the third coding units 1216b and 1216d in the vertical direction.

According to one embodiment, the video decoding device 100 divides the second coding units (1220a, 1220b) generated by splitting them in the horizontal direction, respectively, in the vertical direction to determine the third coding units (1226a, 1226b, 1226c, and 1226d). The video decoding device 100 first processes the third coding units 1226a and 1226b included in the upper second coding unit 1220a in the horizontal direction, and then processes the third coding units 1226a and 1226b included in the lower second coding unit 1220b. The third coding units 1226a, 1226b, 1226c, and 1226d can be processed according to the order 1227 of processing the third coding units 1226c and 1226d in the horizontal direction.

Referring to FIG. 12, the second coding units (1210a, 1210b, 1220a, 1220b) can be divided into square-shaped third coding units (1216a, 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d). there is. The second coding units 1210a and 1210b determined by being divided in the vertical direction and the second coding units 1220a and 1220b determined by being divided in the horizontal direction are divided into different forms, but the third coding unit 1216a is determined later. , 1216b, 1216c, 1216d, 1226a, 1226b, 1226c, 1226d), the result is that the first coding unit 1200 is divided into coding units of the same type. Accordingly, the image decoding device 100 recursively splits the coding unit through a different process based on at least one of block type information and information about the split type mode, and as a result, even if coding units of the same type are determined, the same type A plurality of coding units determined as can be processed in different orders.

FIG. 13 illustrates a process in which the depth of the coding unit is determined as the shape and size of the coding unit change when the coding unit is recursively divided to determine a plurality of coding units according to an embodiment.

According to one embodiment, the video decoding device 100 may determine the depth of a coding unit according to a predetermined standard. For example, the predetermined standard may be the length of the long side of the coding unit. The video decoding device 100 is configured to divide the long side of the current coding unit into 2n (n>0) times the length of the long side of the coding unit before splitting, and the depth of the current coding unit is greater than the depth of the coding unit before splitting. It can be determined that the depth is increased by n. Hereinafter, the coding unit with increased depth will be expressed as a coding unit of lower depth.

Referring to FIG. 13, according to one embodiment, based on block shape information indicating a square shape (for example, the block shape information may indicate '0: SQUARE'), the image decoding apparatus 100 generates a square shape. By dividing 1 coding unit 1300, a second coding unit 1302, a third coding unit 1304, etc. of lower depth can be determined. If the size of the square-shaped first coding unit 1300 is 2Nx2N, the second coding unit 1302 determined by dividing the width and height of the first coding unit 1300 by 1/2 may have a size of NxN. there is. Furthermore, the third coding unit 1304 determined by dividing the width and height of the second coding unit 1302 into 1/2 sizes 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 that of the first coding unit 1300. If the depth of the first coding unit 1300 is D, the depth of the second coding unit 1302, which is 1/2 the width and height of the first coding unit 1300, may be D+1, and the depth of the second coding unit 1302 may be D+1. The depth of the third coding unit 1304, which is 1/4 times the width and height of 1300, may be D+2.

According to one embodiment, block shape information indicating a non-square shape (for example, the block shape information may be '1: NS_VER' indicating a non-square with a height longer than the width, or '1: NS_VER' indicating a non-square with a width longer than the height. 2: may represent NS_HOR′), the image decoding device 100 divides the first coding unit 1310 or 1320, which is non-square, into a second coding unit 1312 or 1322 of lower depth, The third coding unit (1314 or 1324), etc. can be determined.

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

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

According to one embodiment, the image decoding device 100 determines a third coding unit (e.g., 1304, 1314, 1324, etc.) by dividing at least one of the width and height of the second coding unit 1302 of NxN size. It may be possible. That is, the image decoding device 100 divides the second coding unit 1302 in the vertical and horizontal directions to determine a third coding unit 1304 of size N/2xN/2 or a third coding unit 1304 of size N/4xN/2. 3 coding units 1314 can be determined, or a third coding unit 1324 of size N/2xN/4 can be determined.

According to one embodiment, the image decoding device 100 divides at least one of the width and height of the second coding unit 1312 of N/2xN size into third coding units (e.g., 1304, 1314, 1324, etc.). You can also decide. That is, the video decoding device 100 divides the second coding unit 1312 in the horizontal direction into a third coding unit 1304 of size N/2xN/2 or a third coding unit 1324 of size N/2xN/4. ) can be determined or the third coding unit 1314 of size N/4xN/2 can be determined by dividing it in the vertical and horizontal directions.

According to one embodiment, the video decoding device 100 divides at least one of the width and height of the NxN/2-sized second coding unit 1322 into third coding units (e.g., 1304, 1314, 1324, etc.). You can also decide. That is, the image decoding device 100 divides the second coding unit 1322 in the vertical direction into a third coding unit 1304 of N/2xN/2 size or a third coding unit 1314 of N/4xN/2 size. ) can be determined or divided into vertical and horizontal directions to determine a third coding unit 1324 of size N/2xN/4.

According to one embodiment, the video decoding device 100 may divide square-shaped coding units (eg, 1300, 1302, and 1304) in the horizontal or vertical direction. For example, the first coding unit 1300 of size 2Nx2N may be divided in the vertical direction to determine the first coding unit 1310 of size Nx2N, or the first coding unit 1320 of size 2NxN may be determined by dividing in the horizontal direction. You can. According to one 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 of size 2Nx2N in the horizontal or vertical direction is the first coding unit. It may be the same as the depth of unit 1300.

According to one embodiment, the width and height of the third coding unit (1314 or 1324) may correspond to 1/4 times that of the first coding unit (1310 or 1320). If the depth of the first coding unit (1310 or 1320) is D, the depth of the second coding unit (1312 or 1322), which is 1/2 the width and height of the first coding unit (1310 or 1320), may be D+1. And the depth of the third coding unit (1314 or 1324), which is 1/4 times the width and height of the first coding unit (1310 or 1320), may be D+2.

FIG. 14 illustrates an index (part index, hereinafter PID) for classifying depth and coding units that can be determined according to the shape and size of coding units, according to an embodiment.

According to one embodiment, the image decoding device 100 may divide the square-shaped first coding unit 1400 to determine various forms of second coding units. Referring to FIG. 14, the video decoding device 100 divides the first coding unit 1400 into at least one of the vertical and horizontal directions according to information about the split mode to generate second coding units 1402a and 1402b. , 1404a, 1404b, 1406a, 1406b, 1406c, 1406d) can be determined. That is, the image decoding device 100 determines the second coding units 1402a, 1402b, 1404a, 1404b, 1406a, 1406b, 1406c, and 1406d based on information about the segmentation mode for the first coding unit 1400. You can.

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

According to one embodiment, the image decoding device 100 divides the first coding unit 1410, which has a height longer than the width, in the horizontal direction according to information about the split mode to create a plurality of second coding units 1412a and 1412b. , 1414a, 1414b, 1414c). According to one embodiment, the video decoding device 100 divides the first coding unit 1420, which has a width longer than the height, in the vertical direction according to information about the division mode to form a plurality of second coding units 1422a and 1422b. , 1424a, 1424b, 1424c).

According to one embodiment, the second coding units 1412a, 1412b, 1414a, 1414b, and 1414c are determined according to information about the segmentation mode for the non-square first coding unit 1410 or 1420. 1424a, 1424b, 1424c), the depth may be determined based on the length of the long side. For example, the length of one side of the square-shaped second coding units 1412a and 1412b is 1/2 the length of one side of the non-square first coding unit 1410, where the height is longer than the width, so it is a square. The depth of the second coding units 1412a and 1412b is D+1, which is one depth lower than the depth D of the non-square first coding unit 1410.

Furthermore, the image decoding device 100 may divide the non-square first coding unit 1410 into an odd number of second coding units 1414a, 1414b, and 1414c based on information about the division mode. 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 the long side of the non-square second coding units 1414a and 1414c and the length of one side of the square second coding unit 1414b are 1/ of the length of one side of the first coding unit 1410. Since it is double, the depth of the second coding units 1414a, 1414b, and 1414c may be a depth of D+1, which is one depth lower than the depth of the first coding unit 1410, D. The image decoding device 100 corresponds to the above method of determining the depth of coding units related to the first coding unit 1410, and uses a non-square first coding unit 1420 with a width longer than the height. The depth of coding units can be determined.

According to one embodiment, the video decoding device 100 determines an index (PID) for distinguishing divided coding units. When the odd number of divided coding units are not the same size, the size ratio between coding units is determined. Based on this, the index can be determined. Referring to FIG. 14, the coding unit 1414b located in the center among the coding units 1414a, 1414b, and 1414c divided into odd numbers has the same width but a different height from the other coding units 1414a and 1414c. It may be twice the height of fields 1414a and 1414c. That is, in this case, the coding unit 1414b located in the center may include two other coding units 1414a and 1414c. Therefore, if the index (PID) of the coding unit 1414b located in the center according to the scan order is 1, the index of the coding unit 1414c located next in order may be 3, which is increased by 2. In other words, there may be discontinuity in the value of the index. According to one embodiment, the video decoding apparatus 100 may determine whether odd-numbered coding units are of the same size based on the presence of discontinuity in the index for distinguishing between the divided coding units.

According to one embodiment, the video decoding apparatus 100 may determine whether the unit has been divided into a specific division type based on the value of an index for distinguishing a plurality of coding units determined by being divided from the current coding unit. Referring to FIG. 14, the image decoding device 100 divides the first coding unit 1410, which has a rectangular shape with a height longer than the width, to determine even-numbered coding units 1412a and 1412b or odd-numbered coding units 1414a and 1414b. , 1414c) can be determined. The video decoding device 100 may use an index (PID) indicating each coding unit to distinguish each of a plurality of coding units. According to one embodiment, the PID may be obtained from a sample at a predetermined position (eg, upper left sample) of each coding unit.

According to one embodiment, the video decoding device 100 may determine a coding unit at a predetermined position among coding units divided and determined using an index for distinguishing coding units. According to one embodiment, when information about the division form mode for the first coding unit 1410, which has a rectangular shape with a height longer than the width, indicates that the first coding unit 1410 is divided into three coding units, the image decoding device 100 divides the first coding unit 1410 into three coding units. 1410) can be divided into three coding units (1414a, 1414b, 1414c). The video decoding device 100 may allocate an index to each of the three coding units 1414a, 1414b, and 1414c. The video decoding device 100 may compare the indices for each coding unit to determine a middle coding unit among coding units divided into an odd number of coding units. The video decoding apparatus 100 generates a coding unit 1414b having an index corresponding to the middle value among the indices based on the indexes of the coding units, and encodes the coding unit 1414b at the middle position among the coding units determined by dividing the first coding unit 1410. It can be determined as a unit. According to one embodiment, when determining an index for distinguishing divided coding units, the video decoding device 100 may determine the index based on the size ratio between coding units if the coding units do not have the same size. . Referring to FIG. 14, the coding unit 1414b created by dividing the first coding unit 1410 has the same width as the other coding units 1414a and 1414c, but has a different height. It can be twice the height. In this case, if the index (PID) of the coding unit 1414b located in the center is 1, the index of the coding unit 1414c located next in order may be 3, which is increased by 2. In this case, when the index increases uniformly and the increment width changes, the video decoding device 100 may determine that it is divided into a plurality of coding units including a coding unit with a size different from other coding units. According to an example, when information about the split type mode indicates that the video decoding device 100 is divided into an odd number of coding units, the coding unit at a predetermined position (for example, the middle coding unit) among the odd number of coding units is divided into other coding units. The current coding unit can be divided into different sizes. In this case, the video decoding device 100 can determine coding units of different sizes using the index (PID) for the coding unit. However, the above-described index and the size or position of the coding unit at the predetermined position to be determined are specific for explaining one embodiment and should not be interpreted as limited thereto, and various indices and positions and sizes of the coding unit may be used. must be interpreted.

According to one embodiment, the video decoding apparatus 100 may use a predetermined data unit from which recursive division of the coding unit begins.

FIG. 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 one embodiment, a predetermined data unit may be defined as a data unit in which the coding unit begins to be recursively divided using at least one of block type information and information about the division type mode. In other words, it may correspond to the highest depth coding unit used in the process of determining a plurality of coding units that divide the current picture. Hereinafter, for convenience of explanation, this predetermined data unit will be referred to as a standard data unit.

According to one embodiment, the reference data unit may represent a predetermined size and shape. According to one embodiment, a reference coding unit may include MxN samples. Here, M and N may be the same as each other and may be integers expressed as a multiplier of 2. That is, the reference data unit may represent a square or non-square shape, and may then be divided into an integer number of coding units.

According to one embodiment, the video decoding apparatus 100 may divide the current picture into a plurality of reference data units. According to one embodiment, the video decoding apparatus 100 may split a plurality of reference data units for splitting the current picture using information about the split type mode for each reference data unit. The division process of this standard data unit may correspond to the division process using a quad-tree structure.

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

Referring to FIG. 15, the video decoding apparatus 100 may use a standard coding unit 1500 in a square shape, or a standard coding unit 1502 in a non-square shape. According to one embodiment, the shape and size of the reference coding unit can be divided into various data units (e.g., sequence, picture, slice, slice segment (e.g., sequence, picture, slice, slice segment) that may include at least one reference coding unit. slice segment, tile, tile group, maximum coding unit, etc.).

According to one embodiment, the receiving unit (not shown) of the video decoding device 100 may obtain at least one of information about the form of the reference coding unit and information about the size of the reference coding unit from the bitstream for each of the various data units. there is. The process of determining at least one coding unit included in the square-shaped reference coding unit 1500 has been described in detail through the process of dividing the current coding unit 300 of FIG. 3, and the non-square-shaped reference coding unit 1502 Since the process of determining at least one coding unit included in ) has been described above through the process of dividing the current coding unit (400 or 450) of FIG. 4, detailed description will be omitted.

According to one embodiment, the video decoding device 100 determines the size and shape of the reference coding unit according to some data units that are predetermined based on a predetermined condition, and an index for identifying the size and shape of the reference coding unit. can be used. That is, the receiver (not shown) receives a predetermined condition among the various data units (e.g., sequence, picture, slice, slice segment, tile, tile group, maximum coding unit, etc.) from the bitstream. As a data unit that satisfies (e.g., a data unit with a size smaller than a slice), the size and shape of the standard coding unit for each slice, slice segment, tile, tile group, maximum coding unit, etc. Only an index for identification can be obtained. The video decoding apparatus 100 can determine the size and shape of the reference data unit for each data unit that satisfies the predetermined condition by using the index. If information about the form of the standard coding unit and information about the size of the standard coding unit are obtained and used from the bitstream for each data unit of a relatively small size, the bitstream use efficiency may not be good, so the form of the standard coding unit Instead of directly obtaining information about and the size of the reference coding unit, only the index can be obtained and used. In this case, at least one of the size and shape of the standard coding unit corresponding to the index indicating the size and shape of the standard coding unit may be predetermined. That is, the video decoding device 100 selects at least one of the size and shape of a 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 standard for index acquisition. You can decide.

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

FIG. 16 illustrates a processing block that serves as a standard for determining the decision order of a reference coding unit included in the picture 1600, according to an embodiment.

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

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

According to one embodiment, the receiving unit (not shown) of the video decoding apparatus 100 may obtain information about the size of a processing block from the bitstream for each specific data unit. For example, information about the size of a processing block can be obtained from a bitstream in data units such as an image, sequence, picture, slice, or slice segment. That is, the receiver (not shown) can obtain information about the size of the processing block from the bitstream for each of the several data units, and the video decoding device 100 divides the picture using the information about the size of the obtained processing block. The size of at least one processing block may be determined, and the size of this processing block may be an integer multiple of the standard coding unit.

According to one embodiment, the image decoding apparatus 100 may determine the size of the processing blocks 1602 and 1612 included in the picture 1600. For example, the image decoding apparatus 100 may determine the size of the processing block based on information about the size of the processing block obtained from the bitstream. Referring to FIG. 16, according to one embodiment, the video decoding device 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. You can decide. The video decoding apparatus 100 may determine the order in which at least one reference coding unit is determined within at least one processing block.

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

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

According to one embodiment, the video decoding apparatus 100 may obtain information about the decision order of the reference coding unit for each specific data unit from the bitstream. For example, the receiver (not shown) converts information about the decision order of the standard coding unit into data units such as image, sequence, picture, slice, slice segment, tile, tile group, and processing block. It can be obtained from each bitstream. Since information about the decision order of the standard coding unit indicates the decision order of the standard coding unit within a processing block, information about 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 one embodiment, the receiving unit (not shown) may obtain information about the reference coding unit decision order as information related to the processing blocks 1602 and 1612 from the bitstream, and the video decoding device 100 may obtain the processing blocks 1602 and 1612. The order of determining at least one reference coding unit included in pictures 1602 and 1612 may be determined, and at least one reference coding unit included in the picture 1600 may be determined according to the determining order of the coding units. Referring to FIG. 16 , the image decoding apparatus 100 may determine a decision order (1604, 1614) of at least one reference coding unit related to each processing block (1602, 1612). For example, when information about the decision order of the reference coding unit is obtained for each processing block, the decision order of the reference coding unit associated with each processing block 1602 and 1612 may be different for each processing block. If the reference coding unit determination order 1604 related to the processing block 1602 is a raster scan order, the reference coding unit included in the processing block 1602 may be determined according to the raster scan order. On the other hand, if the reference coding unit determination order 1614 related to another processing block 1612 is 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.

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

According to one embodiment, the video decoding apparatus 100 may obtain and use block type information indicating the type of the current coding unit or information on a split type mode indicating a method of dividing the current coding unit from the bitstream. Block type information or information about the partition type mode may be included in the bitstream associated with various data units. For example, the video decoding device 100 includes a sequence parameter set, a picture parameter set, a video parameter set, a slice header, and a slice segment header. Block type information or information about the segment type mode included in the segment header, tile header, and tile group header can be used. Furthermore, the video decoding apparatus 100 may obtain and use syntax elements corresponding to block type information or information about the split type mode from the bitstream for each maximum coding unit, reference coding unit, and processing block.

17 to 20, an image encoding device, an image decoding device, an image encoding method, and an image decoding method for encoding or decoding an image based on various types of coding units according to various embodiments are described.

17 and 18 are diagrams for explaining a method of disallowing division into chroma blocks of a certain size or less depending on the division tree type, according to various embodiments.

Figures 17A and 17B are diagrams for explaining a method of not allowing division into chroma blocks of a certain size or less when the division tree type is a single tree, according to various embodiments.

FIG. 17A is a diagram illustrating a method of not allowing splitting of chroma blocks smaller than a certain size when the splitting tree type is a single tree, according to one embodiment.

When the split tree type is a single tree, the tree structure of coding units of the luma image and the tree structure of coding units of the chroma image may be determined according to the tree structure of one coding unit.

Referring to FIG. 17A, when the split tree type is a single tree, the image decoding apparatus 100 can binary split the luma block 1705 and the corresponding chroma block 1710 in the vertical direction. The image decoding device 100 may determine the minimum allowable size of the luma block to be 4x4, and since the size of the block 1715 to be generated by binary division in the vertical direction is larger than the minimum allowable size of the luma block, the image decoding device (100) may binary divide the luma block 1705 in the vertical direction.

The image decoding device 100 may determine the minimum allowable size of the chroma block to be 4x4, and the size of the block to be generated by binary division in the vertical direction is smaller than the minimum allowable size of the chroma block. , it may be determined not to divide the chroma block 1710.

The image decoding apparatus 100 may binary divide the luma block 1715 and the corresponding chroma block 1710 in the horizontal direction. The image decoding device 100 may determine the minimum allowable size of the luma block to be 4x4, and since the size of the block 1720 to be generated by binary division in the horizontal direction is the same as the minimum allowable size of the luma block, the image decoding device (100) may binary divide the luma block 1715 in the horizontal direction.

The image decoding device 100 may determine the minimum allowable size of the chroma block to be 4x4, and the size of the block to be generated by binary division in the horizontal direction is smaller than the minimum allowable size of the chroma block. , it may be decided not to split the chroma block any further.

FIG. 17B is a diagram illustrating a method of disallowing division into chroma blocks of a certain size or less when the division tree type is a single tree, according to one embodiment.

FIG. 17B is a diagram illustrating a method of disallowing division into chroma blocks of a certain size or less when the division tree type is a single tree, according to another embodiment.

Referring to FIG. 17b, when the split tree type is a single tree, the image decoding apparatus 100 may tri-split the luma block 1755 and the corresponding chroma block 1760 in the vertical direction. The image decoding apparatus 100 may determine the minimum allowable area of the luma block to be 16, and since the area of the block 1765 to be generated by tri-division in the vertical direction is greater than or equal to the minimum allowable area of the luma block, the image The decoding device 100 may tri-split the luma block 1755 in the vertical direction.

The image decoding device 100 may determine the minimum allowable area of the chroma block to be 16, and since the area of the block to be generated by tri-division in the vertical direction is smaller than the minimum allowable area of the chroma block, the image decoding device 100 may determine not to split the chroma block 1760.

FIG. 18 is a diagram illustrating a method of not allowing splitting of chroma blocks smaller than a certain size when the splitting tree type is dual tree, according to one embodiment.

When the split tree type is a dual tree, the tree structure of coding units of the luma image and the tree structure of coding units of the chroma image may be determined separately.

Referring to FIG. 18, the image decoding device 100 may determine the minimum allowable size of the chroma block to be 4x4, and the blocks to be generated by dividing the chroma blocks 1800, 1810, 1820, and 1825 according to a specific partition type. Since the size is smaller than 4x4, which is the minimum allowable size of the chroma block, it may be determined not to divide the chroma block 1800 according to a specific division type.

When the division type of the chroma block 1800 is quad division, the image decoding device 100 determines that the size of the block to be generated by dividing the chroma block 1800 according to the quad division is 2x2, which is smaller than the minimum allowable size of 4x4. , it may be determined not to divide the chroma block 1800 according to quad division. At this time, the image decoding apparatus 100 may determine, based on a condition based on the size of the chroma block 1800, whether the size of the block to be divided and created is smaller than the minimum allowable size of 4x4. For example, the image decoding device 100 determines whether the height or width of the chroma block 1800 is less than or equal to 4, and the size of the block to be divided and generated according to the decision result is 4x4, which is the minimum allowable size. You can decide that it is smaller than .

When the division type of the chroma block 1810 is binary division, the image decoding device 100 determines that the size of the block to be generated by dividing the chroma block 1810 according to the binary division is 4x2 or 2x4, which is larger than the minimum allowable size of 4x4. Since it is small, it can be decided not to divide the chroma block 1810 according to binary division. At this time, the image decoding apparatus 100 may determine, based on a condition based on the area of the chroma block 1810, whether the size of the block to be divided and created is smaller than the minimum allowable size of 4x4. For example, the image decoding device 100 determines whether the area of the chroma block 1810 is less than or equal to 16, and determines that the size of the block to be divided and created according to the decision result is smaller than the minimum allowable size of 4x4. You can decide.

When the partition type of the chroma blocks 1820 and 1825 is tri-partition, the image decoding apparatus 100 determines that the size of the block to be generated by dividing the chroma blocks 1820 and 1825 according to the tri-partition is 4x2 or 2x4, which is the minimum allowable size. Since it is smaller than the size of 4x4, it can be decided not to divide the chroma blocks (1820, 1825) according to trie division.

At this time, the image decoding device 100 may determine whether the size of the block to be divided and created is smaller than the minimum allowable size of 4x4, based on a condition based on the areas of the chroma blocks 1820 and 1825. For example, the image decoding device 100 determines whether the area of the chroma blocks 1820 and 1825 is less than or equal to 32, and the size of the block to be divided and generated according to the decision result is 4x4, which is the minimum allowable size. You can decide that it is smaller than .

The image decoding apparatus 100 can improve throughput when decoding a chroma block by always determining the coding unit of the chroma block to be larger than or equal to the minimum allowable size.

19 and 20 are diagrams for explaining a method of dividing a block located at a picture boundary, according to various embodiments.

FIG. 19 is a diagram illustrating a method of dividing a block located at the boundary of a picture using a division type mode based on the direction of the boundary, according to an embodiment.

The video decoding apparatus 100 can hierarchically quad-divide blocks by performing quad-division recursively. At this time, the range of the size of the block that can be created by quad division can be determined. The video decoding apparatus 100 may hierarchically quad-divide a block by recursively performing quad-division within the range of the size of the block that can be created by quad-division.

The video decoding apparatus 100 may recursively perform binary division or trie division on a block generated by hierarchical quad division. At this time, the division depth of binary division or tri division may be determined in advance. The image decoding apparatus 100 may recursively perform binary division or tri-division based on a predetermined division depth of binary division or tri-division from a block generated by hierarchical quad division.

Referring to FIG. 19, when the current block 1905 is located on a picture boundary 1910, the video decoding apparatus 100 performs splitting allowed from the current block 1905 without obtaining split type mode information from the bitstream. The current block 1905 can be divided according to the shape mode. For example, if the allowable split type of the current block mode is tri-split or binary split, the video decoding apparatus 100 may binary split (or tri-split) the current block 1905. At this time, the division direction may be determined to be horizontal according to the direction of the picture boundary 1910 of the current block 1905.

The video decoding apparatus 100 may quad-split the current block 1910 when the allowable split type of the current block mode is not tri-split or binary split.

At this time, the image decoding apparatus 100 may recursively divide the current block 1905 until the block generated by division is not located on the picture boundary 1910.

20A to 20B show a method of dividing a block at the border of a picture based on whether the minimum block size is obtained when binary dividing a block at the border of a picture by applying an allowable binary division depth according to an embodiment. This is a drawing for explanation.

Referring to FIG. 20A, when the size of the current block 2000 is 128x128, the allowable partition type of the current block 2000 is binary partition, and the allowable partition depth of the current block 2000 is 3, the video decoding device (100) If the current block 2000 is located on the image boundary 2005 of the current picture, binary division is performed based on the first division boundary 2010, and binary division is performed based on the second division boundary 2015. Division may be performed, and binary division may be performed based on the third division boundary 2020. Since binary segmentation has been performed as much as the binary segmentation depth, the video decoding apparatus 100 can no longer perform binary segmentation. Accordingly, the size of the block 2025 inside the image boundary 2005 determined in the coding unit may be 16x128. However, since the size of the block 2025 determined as a coding unit is not small, there is a problem that decoding efficiency is lowered when various motion information and pixel value information are included in it.

Referring to FIG. 20b, when the size of the current block 2030 is 128x128, the allowable partition type of the current block 2030 is binary partition, and the allowable partition depth of the current block 2030 is 3, the video decoding device If (100) is located on the image boundary 2035 of the current picture, the size of the current block 2030 and the allowable division depth for binary division of the current block are taken into account to represent the block to be created by recursively binary division from the current block. If the size is less than or equal to the minimum block size (e.g., 4x4), perform binary division, and considering the allowable division depth of binary division, the size of the block generated by recursive binary division from the current block is equal to the minimum block. If it is larger than the size, quad splitting can be performed.

Since the size of the block generated by recursively binary dividing the current block 2030 in consideration of the allowable division depth of binary division is larger than the minimum block size, the image decoding device 100 uses the first division boundary 2040 as the basis. You can perform quad division on the current block 2030.

The image decoding device 100 considers the maximum allowable division depth of binary division and sets the second division boundary 2050 because the size of the block generated by recursively binary division from the current block 2045 is larger than the minimum block size. As a basis, quad division can be performed on the current block (2045).

The image decoding device 100 considers the maximum allowable division depth of binary division and sets the third division boundary 2060 because the size of the block recursively binary divided from the current block 2055 is smaller than or equal to the minimum block size. Based on this, binary division can be performed on the current block 2055.

The size of the block 2065 inside the image boundary 2035 generated by performing binary division on the current block 2055 based on the third division boundary 2060 is 16x32, and the image decoding device 100 uses the block Additional binary division may be performed on (2065). Accordingly, the block determined as the coding unit may be small in size, unlike FIG. 20A, and decoding efficiency may be relatively high.

Above, with reference to FIGS. 20A and 20B, the video decoding device 100 determines the size of the current blocks 2000 and 2030 to be 128x128, and determines the allowable division type of the current blocks 2000 and 2030 as binary division. , when the allowable division depth of the current block (2000, 2030) is determined to be 3, a method of dividing the current block (2000, 2030) located on the picture boundary has been described, but is not limited to this, and is as follows. If the current block is located on a picture boundary according to the pseudo code, the current block can be split.

[Psudo Code]

For example, the video decoding device 100 that follows the above Psudo Code recursively divides as much as the division depth allowed by binary division based on the larger value of the height or width of the current block (in a binary tree). When performing a binary division, if the corresponding edge is of a certain size (or smaller) (here, the specific size may be the size of the minimum block, but may also be a size set by the user), the current Blocks can be split recursively (partitioning based on binary trees). In other cases, the video decoding device 100 may split the current block according to quad division. Specifically, if the allowed binary division depth (bt_depth) is 3, the current block is divided according to binary division only if the larger of the height and width of the current block is less than or equal to the minimum size (min_bt_size)x2x2x2 (i.e., minimum size x 8). It can be divided recursively.

Above, with reference to FIGS. 20A to 20B, the video decoding device 100 has described a method of performing binary division or quad division in consideration of the binary division depth, but the method is not limited thereto, and similarly, the binary (and tri) division depth Those skilled in the art can easily understand that binary division, tri-division, or quad division can be performed by considering .

So far, we have looked at various embodiments. A person skilled in the art to which this disclosure pertains will understand that this 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 from an illustrative rather than a restrictive perspective. The scope of the present disclosure is indicated in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present disclosure.

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

Claims (4)

Obtaining one or more luma coding units based on at least one of a division direction and a division type of the luma block;
Decoding a luma image based on the obtained one or more luma coding units;
If the area of the chroma block is less than or equal to a predetermined area according to the tri-division type of the chroma block, it is determined not to allow division of the chroma block according to the tri-division type, and partition types other than the tri-division type are determined. Obtaining one or more chroma coding units according to a method; and
An image decoding method comprising decoding a chroma image based on the obtained one or more chroma coding units.
Obtaining one or more luma coding units based on at least one of the division direction and division type of the luma block,
Decode the luma image based on the obtained one or more luma coding units,
If the area of the chroma block is less than or equal to a predetermined area according to the tri-division type of the chroma block, it is determined not to allow division of the chroma block according to the tri-division type, and partition types other than the tri-division type are determined. Obtaining one or more chroma encoding units according to
An image decoding device comprising at least one processor that decodes a chroma image based on the one or more obtained chroma coding units .
determining one or more luma coding units based on at least one of a division direction and a division type of the luma block;
Encoding a luma image based on the determined one or more luma coding units;
If the area of the chroma block is less than or equal to a predetermined area according to the tri-division type of the chroma block, it is determined not to allow division of the chroma block according to the tri-division type, and partition types other than the tri-division type are determined. determining one or more chroma coding units accordingly; and
An image encoding method comprising encoding a chroma image based on the determined one or more chroma coding units.
determining one or more luma coding units based on at least one of a division direction and a division type of the luma block;
Encoding a luma image based on the determined one or more luma coding units;
If the area of the chroma block is less than or equal to a predetermined area according to the tri-division type of the chroma block, it is determined not to allow division of the chroma block according to the tri-division type, and partition types other than the tri-division type are determined. determining one or more chroma coding units accordingly; and
A computer-readable recording medium storing a bitstream generated by an image encoding method including the step of encoding a chroma image based on the determined one or more chroma coding units.