EP-4738829-A2 - METHOD AND APPARATUS FOR ENCODING/DECODING VIDEO USING MAXIMUM SIZE LIMITATION OF CHROMA TRANSFORM BLOCK, AND METHOD FOR TRANSMITTING BITSTREAM

EP4738829A2EP 4738829 A2EP4738829 A2EP 4738829A2EP-4738829-A2

Abstract

An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may include determining a prediction mode of a current block, generating a prediction block of the current block based on inter prediction mode information, based on the prediction mode of the current block being an inter prediction mode, generating a residual block of the current block based on a transform block of the current block, and reconstructing the current block based on the prediction block and the residual block of the current bloc.

Inventors

LI, LING
NAM, JUNG HAK

Assignees

LG Electronics Inc.

Dates

Publication Date: 20260506
Application Date: 20200624

Claims (3)

An decoding apparatus for an image decoding, the decoding apparatus comprising: a memory; and at least one processor connected to the memory, the at least one processor configured to: obtain prediction information and residual information for a current block from a received bitstream; determine (S3010) a prediction mode of the current block based on the prediction information; generate (S3020) an inter prediction block of the current block, based on the determined prediction mode of the current block being an inter prediction mode; determine whether to split a transform block for the current block into one or more sub-transform blocks based on comparison between a size of the transform block and a maximum size of the transform block to obtain the one or more sub-transform blocks; generate (S3030) a residual block of the current block based on the one or more sub-transform blocks; and reconstruct (S3040) the current block based on the inter prediction block and the residual block of the current block, wherein the transform block for the current block is obtained by performing dequantization based on the residual information for the current block, wherein, based on the current block being a chroma block, the maximum size of the transform block comprises a maximum width of the transform block and a maximum height of the transform block, the maximum width of the transform block is derived by dividing a maximum size of a luma transform block corresponding to the current block by a ratio of the width of a luma block to the width of a chroma block, the ratio being determined based on a color format of the current block, and the maximum height of the transform block is derived by dividing the maximum size of the luma transform block corresponding to the current block by a ratio of the height of the luma block to the height of the chroma block, the ratio being determined based on the color format of the current block.
An encoding apparatus for an image encoding, the encoding apparatus comprising: a memory; and at least one processor connected to the memory, the at least one processor configured to: determine (S2910) a current block by splitting an image; determine a prediction mode of the current block; generate (S2920) an inter prediction block of the current block based on the determined prediction mode of the current block being an inter prediction mode; generate (S2930) a residual block of the current block based on the inter prediction block; and encode (S2940) prediction information for the prediction mode and residual information for the residual block to generate a bitstream, wherein the residual block is encoded by determining whether to split a transform block for the residual block into one or more sub-transform blocks based on comparison between a size of the transform block and a maximum size of the transform block to obtain the one or more sub-transform blocks, wherein the transform block for the residual block is obtained by applying transform to the residual block, wherein, based on the current block being a chroma block, the maximum size of the transform block comprises a maximum width of the transform block and a maximum height of the transform block, the maximum width of the transform block is derived by dividing a maximum size of a luma transform block corresponding to the current block by a ratio of the width of a luma block to the width of a chroma block, the ratio being determined based on a color format of the current block, and the maximum height of the transform block is derived by dividing the maximum size of the luma transform block corresponding to the current block by a ratio of the height of the luma block to the height of the chroma block, the ratio being determined based on the color format of the current block.
An apparatus for transmitting a bitstream, the apparatus comprising: at least one processor configured to obtain the bitstream, wherein the bitstream is generated based on determining a current block by splitting an image, determining a prediction mode of the current block, generating an inter prediction block of the current block based on the determined prediction mode of the current block being an inter prediction mode, generating a residual block of the current block based on the inter prediction block, encoding prediction information for the prediction mode and residual information for the residual block; and a transmitter configured to transmit the bitstream, wherein the residual block is encoded by determining whether to split a transform block for the residual block into one or more sub-transform blocks based on comparison between a size of the transform block and a maximum size of the transform block to obtain the one or more sub-transform blocks, wherein the transform block for the residual block is obtained by applying transform to the residual block, wherein, based on the current block being a chroma block, the maximum size of the transform block comprises a maximum width of the transform block and a maximum height of the transform block, the maximum width of the transform block is derived by dividing a maximum size of a luma transform block corresponding to the current block by a ratio of the width of a luma block to the width of a chroma block, the ratio being determined based on a color format of the current block, and the maximum height of the transform block is derived by dividing the maximum size of the luma transform block corresponding to the current block by a ratio of the height of the luma block to the height of the chroma block, the ratio being determined based on the color format of the current block.

Description

Technical Field The present disclosure relates to an image encoding/decoding method and apparatus, and, more particularly, to a method and apparatus for encoding/decoding an image by limiting a maximum size of a chroma transform block, and a method of transmitting a bitstream generated by the image encoding method/apparatus of the present disclosure. Background Art Recently, demand for high-resolution and high-quality images such as high definition (HD) images and ultra high definition (UHD) images is increasing in various fields. As resolution and quality of image data are improved, the amount of transmitted information or bits relatively increases as compared to existing image data. An increase in the amount of transmitted information or bits causes an increase in transmission cost and storage cost. Accordingly, there is a need for high-efficient image compression technology for effectively transmitting, storing and reproducing information on high-resolution and high-quality images. Disclosure Technical Problem An object of the present disclosure is to provide an image encoding/decoding method and apparatus with improved encoding/decoding efficiency. An object of the present disclosure is to provide an image encoding/decoding method and apparatus capable of improving encoding/decoding efficiency by limiting a maximum size of a chroma transform block. Another object of the present disclosure is to provide a method of transmitting a bitstream generated by an image encoding method or apparatus according to the present disclosure. Another object of the present disclosure is to provide a recording medium storing a bitstream generated by an image encoding method or apparatus according to the present disclosure. Another object of the present disclosure is to provide a recording medium storing a bitstream received, decoded and used to reconstruct an image by an image decoding apparatus according to the present disclosure. The technical problems solved by the present disclosure are not limited to the above technical problems and other technical problems which are not described herein will become apparent to those skilled in the art from the following description. Technical Solution An image decoding method performed by an image decoding apparatus according to an aspect of the present disclosure may include determining a prediction mode of a current block, generating a prediction block of the current block based on inter prediction mode information, based on the prediction mode of the current block being an inter prediction mode, generating a residual block of the current block based on a transform block of the current block, and reconstructing the current block based on the prediction block and the residual block of the current block. In this case, a size of the transform block may be determined based on a color component of the current block. An image decoding apparatus according to an aspect of the present disclosure may include a memory and at least one processor. The at least one processor may determine a prediction mode of a current block, generate a prediction block of the current block based on inter prediction mode information, based on the prediction mode of the current block being an inter prediction mode, generate a residual block of the current block based on a transform block of the current block, and reconstruct the current block based on the prediction block and the residual block of the current block. In this case, a size of the transform block may be determined based on a color component of the current block. An image encoding method performed by an image encoding apparatus according to an aspect of the present disclosure may include determining a current block by splitting an image, generating an inter prediction block of the current block, generating a residual block of the current block based on the inter prediction block, and encoding inter prediction mode information of the current block. In this case, the residual block may be encoded based on a size of a transform block of the current block, and the size of the transform block may be determined based on a color component of the current block. In addition, a transmission method according to another aspect of the present disclosure may transmit a bitstream generated by the image encoding apparatus or the image encoding method of the present disclosure. In addition, a computer-readable recording medium according to another aspect of the present disclosure may store the bitstream generated by the image encoding apparatus or the image encoding method of the present disclosure. The features briefly summarized above with respect to the present disclosure are merely exemplary aspects of the detailed description below of the present disclosure, and do not limit the scope of the present disclosure. Advantageous Effects According to the present disclosure, it is possible to provide an image encoding/decoding method and apparatus with improved encoding