BR-122022006107-B1 - A method of decoding and encoding images performed by an image decoding and encoding device and a non-transient computer-readable recording medium storing a bit stream that is generated by an image encoding method.

BR122022006107B1BR 122022006107 B1BR122022006107 B1BR 122022006107B1BR-122022006107-B1

Abstract

The objective of the present invention is to provide a method and apparatus for intraprediction. Furthermore, the objective of the present invention is to provide a method and apparatus for intraprediction on a sub-block unit basis. Additionally, the objective of the present invention is to provide a method and apparatus for determining a division and coding order of sub-block units.

Inventors

Kim Ki Baek

Assignees

B1 INSTITUTE OF IMAGE TECHNOLOGY, INC

Dates

Publication Date: 20260310
Application Date: 20190401
Priority Date: 20180401

Claims (6)

1. Image decoding method performed by an image decoding device, the method characterized by comprising: generating a coding block using tree-based partitioning, the tree-based partitioning comprising dividing a square block into four square blocks having the same size; generating a plurality of sub-blocks by performing index-based partitioning for the coding block, the index-based partitioning comprising a first partitioning and a second partitioning, the first partitioning dividing a 4N x 4M coding block into four identical 4N x M sub-blocks or four identical N x 4M sub-blocks, N being equal to or different from M, and the second partitioning dividing a coding block into two equal parts horizontally or vertically; generate a prediction block from the coding block by performing intra-prediction for each of the plurality of sub-blocks; obtain a quantized transform coefficient for the coding block; obtain a transform coefficient for the coding block by performing inverse quantization on the quantized transform coefficient; generate a residual block from the coding block; and reconstruct the coding block based on the prediction block and the residual block, where the residual block is generated by the inverse transformation of the transform coefficient, where the intra-prediction for each of the plurality of sub-blocks is performed based on the same intra-prediction mode, and where whether or not the first partitioning or the second partitioning should be performed is determined based on the size of the coding block.
2. Image decoding method according to claim 1, characterized by further comprising: determining whether index-based partitioning should be performed for the encoding block based additionally on a property of the encoding block.
3. Image decoding method according to claim 2, characterized in that: the encoding block property comprises at least one of an area, width or height of the encoding block.
4. Image decoding method, according to claim 1, characterized in that: a type of index-based partitioning is determined based additionally on a signed index for the encoding block or on a property of the encoding block.
5. Image coding method performed by an image coding device, characterized in that it comprises: generating a coding block using tree-based partitioning, the tree-based partitioning comprising dividing a square block into four square blocks having the same size; generating a plurality of sub-blocks by performing index-based partitioning for the coding block, the index-based partitioning comprising a first partitioning and a second partitioning, the first partitioning dividing a 4N x 4M coding block into four identical 4N x M sub-blocks or four identical N x 4M sub-blocks, N being equal to or different from M, and the second partitioning dividing a coding block into two equal parts horizontally or vertically; and generate a prediction block from the coding block by performing intra-prediction for each of the plurality of sub-blocks; generate a residual block from the coding block based on the prediction block; generate a transform coefficient by transforming the residual block; generate a quantized transform coefficient by quantizing the transform coefficient; and re-encode the coding block by encoding the quantized transform coefficient, wherein the intra-prediction for each of the plurality of sub-blocks is performed based on the same intra-prediction mode, and whether or not the first partitioning or the second partitioning should be performed is determined based on the size of the coding block.
6. A non-transient, computer-readable recording medium storing a bitstream that is generated by an image encoding method, the method characterized in that it comprises: generating an encoding block using tree-based partitioning, the tree-based partitioning comprising dividing a square block into four square blocks having the same size; generating a plurality of sub-blocks by performing index-based partitioning for the encoding block, the index-based partitioning comprising a first partitioning and a second partitioning, the first partitioning dividing a 4N x 4M encoding block into four identical 4N x M sub-blocks or four identical N x 4M sub-blocks, N being equal to or different from M, and the second partitioning dividing an encoding block into two equal parts horizontally or vertically; and generate a prediction block from the coding block by performing intra-prediction for each of the plurality of sub-blocks; generate a residual block from the coding block based on the prediction block; generate a transform coefficient by transforming the residual block; generate a quantized transform coefficient by quantizing the transform coefficient; and re-encode the coding block by encoding the quantized transform coefficient, wherein the intra-prediction for each of the plurality of sub-blocks is performed based on the same intra-prediction mode, and whether or not the first partitioning or the second partitioning should be performed is determined based on the size of the coding block.

Description

TECHNICAL FIELD [001]This disclosure relates to a technique for encoding and decoding an image and, more particularly, to a method and apparatus for performing intra-prediction encoding/decoding. FUNDAMENTALS OF THE TECHNIQUE [002] Along with the widespread use of the Internet and portable terminals and the development of information and communication technology, multimedia data is increasingly being used. Consequently, in order to provide various services or perform various tasks through image prediction in various systems, there is a pressing need to improve the performance and efficiency of an image processing system. However, research and development achievements have not yet kept pace with this trend. [003]As such, an existing method and apparatus for encoding/decoding an image needs performance improvement in image processing, particularly in image encoding or image decoding. DISCLOSURE TECHNICAL PROBLEM [004] It is an objective of this disclosure to provide a method and apparatus for performing intra-prediction. It is another objective of this disclosure to provide a method and apparatus for performing sub-block intra-prediction. It is another objective of this disclosure to provide a method and apparatus for performing sub-block partitioning and determining a coding order for the sub-blocks. TECHNICAL SOLUTION [005]In a method and apparatus for image encoding/decoding according to the present disclosure, a group of candidate partition types for a current block is configured, and a partition type of the current block into sub-blocks is determined based on the candidate group and a candidate index, an intra-prediction mode is derived in units of the current block, and the current block is intra-predicted based on the intra-prediction mode of the current block and the partition type. ADVANTAGEOUS EFFECTS [006]According to the present disclosure, encoding/decoding performance can be improved through intra-prediction by sub-block. Furthermore, according to the present disclosure, prediction accuracy can be increased by efficiently configuring a group of partition type candidates by sub-block. Additionally, according to the present disclosure, intra-prediction encoding/decoding efficiency can be improved by adapting an encoding order by sub-block. DESCRIPTION OF THE DRAWINGS [007]Figure 1 is a conceptual diagram illustrating an image encoding and decoding system according to an embodiment of the present disclosure. [008]Figure 2 is a block diagram illustrating an image encoding apparatus according to an embodiment of the present disclosure. [009]Figure 3 is a block diagram illustrating an image decoding device according to an embodiment of the present disclosure. [0010]Figure 4 is an exemplary diagram illustrating various types of partitions that can be obtained in a block splitter of the present disclosure. [0011]Figure 5 is an exemplary diagram illustrating the intra-prediction modes according to one embodiment of the present disclosure. [0012]Figure 6 is an exemplary diagram illustrating a configuration of reference pixels used for intra-prediction according to an embodiment of the present disclosure. [0013]Figure 7 is a conceptual diagram illustrating a target block for intra-prediction and blocks neighboring the target block according to an embodiment of the present disclosure. [0014]Figure 8 is a diagram illustrating various types of sub-block partitioning that can be obtained from a coding block. [0015]Figure 9 is an exemplary diagram illustrating reference pixel regions used for intra-prediction modes according to an embodiment of the present disclosure. [0016]Figure 10 is an exemplary diagram illustrating the available coding orders in the right-up diagonal prediction modes according to an embodiment of the present disclosure. [0017]Figure 11 is an exemplary diagram illustrating the available coding orders in horizontal modes according to an embodiment of the present disclosure. [0018]Figure 12 is an exemplary diagram illustrating the available coding orders in the right-down diagonal prediction modes according to an embodiment of the present disclosure. [0019]Figure 13 is an exemplary diagram illustrating the available coding orders in vertical modes according to an embodiment of the present disclosure. [0020]Figure 14 is an exemplary diagram illustrating the available coding orders in the diagonal down-left prediction modes according to an embodiment of the present disclosure. [0021]Figure 15 is an exemplary diagram illustrating coding orders based on intra-prediction modes and partition types according to an embodiment of the present disclosure. BEST WAY [0022]In a method and apparatus for image encoding/decoding according to the present disclosure, a group of available partition type candidates for a current block can be configured, a partition type of the current block into sub-blocks can be determined based on the candidate group and a candidate index, an intra-prediction mode can be derive