BR-112021026535-B1 - IMAGE DECODING/ENCODING METHOD PERFORMED BY AN IMAGE DECODING/ENCODING DEVICE, METHOD OF TRANSMITTING A BIT STREAM GENERATED BY AN IMAGE ENCODING METHOD, and NON-TRANSIENT COMPUTER-READABLE RECORDING MEDIUM

BR112021026535B1BR 112021026535 B1BR112021026535 B1BR 112021026535B1BR-112021026535-B1

Abstract

IMAGE ENCODING/DECODING METHOD, APPARATUS AND METHOD FOR TRANSMITTING BIT STREAM USING THE MAXIMUM SIZE LIMITATION OF THE CHROMA TRANSFORMATION BLOCK. A method and an apparatus for encoding/decoding a video are provided. A method for decoding a video performed by an image decoding apparatus according to the present disclosure may comprise the steps of: determining a prediction mode of a current block; generating a prediction block for the current block based on the interprediction mode information when the prediction mode of the current block is an interprediction mode; generating a residual block of the current block based on a transformation block of the current block; and reconstructing the current block based on the residual block of the current block and the prediction block.

Inventors

Ling Li
JUNG HAK NAM

Assignees

LG ELECTRONICS INC

Dates

Publication Date: 20260317
Application Date: 20200624
Priority Date: 20190624

Claims (9)

1. Image decoding method performed by an image decoding device, the image decoding method comprising: determining a prediction mode of a current block; generating a prediction block of the current block based on the information of the interprediction mode, based on the prediction mode of the current block being an interprediction mode; generating a residual block of the current block based on a transform block of the current block; Reconstructing the current block based on the prediction block and the residual block of the current block, CHARACTERIZED in that a maximum width and a maximum height of the transform block are determined separately based on a color component of the current block, wherein, based on the color component of the current block being a chroma component, the maximum width and maximum height of the transform block are determined based on a maximum size of a luma transform block corresponding to the current block and a color format of the current block, wherein, based on the color component of the current block being a chroma component, a position of an upper-left sample of the transform block is determined based on a position of an upper-left sample of a luma block corresponding to the current block and the color format of the current block, wherein, based on the color component of the current block being the chroma component, the maximum width of the transform block is derived by dividing the maximum size of the luma transform block corresponding to the current block by a ratio between a width of a luma block and a width of a Chroma block, the ratio being determined based on the color format of the current block, where, based on the color component of the current block being the chroma component, 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 between a luma block height and a chroma block height, the ratio being determined based on the color format of the current block.
2. Image decoding method, according to claim 1, CHARACTERIZED in that a transform block width is determined based on the maximum transform block width.
3. Image decoding method, according to claim 2, CHARACTERIZED in that a transform block height is determined based on the maximum transform block height.
4. Image decoding method, according to claim 1, CHARACTERIZED in that, based on the color format of the current block being a format that specifies that the width of a chroma block is half the width of a corresponding luma block, a maximum size of the transform block is determined to be 32x64.
5. Image decoding method, according to claim 1, CHARACTERIZED in that the maximum width and maximum height are determined as being different from each other based on the color format being of a 4:2:2 format.
6. Image decoding method, according to claim 1, CHARACTERIZED in that the current block is a chroma block and, based on the transform block being divided into a plurality of lower layer transform blocks, an upper left position of the lower layer transform blocks is determined based on a maximum width and a maximum height of the transform block.
7. Image coding method performed by an image coding device, the image coding method comprising: determining a current block by dividing an image; generating an interprediction block from the current block; generating a residual block from the current block based on the interprediction block; and encode information in the current block's interpretation mode, wherein the residual block is encoded based on the size of a transform block of the current block, and CHARACTERIZED in that a maximum width and a maximum height of the transform block are determined separately based on a color component of the current block, wherein, based on the color component of the current block being a chroma component, the maximum width and maximum height of the transform block are determined based on a maximum size of a luma transform block corresponding to the current block and a color format of the current block, wherein, based on the color component of the current block being a chroma component, a position of an upper-left sample of the transform block is determined based on a position of an upper-left sample of a luma block corresponding to the current block and the color format of the current block, wherein, based on the color component of the current block being the chroma component, the maximum width of the transform block is derived by dividing the maximum size of the luma transform block corresponding to the current block by a The ratio between the width of a luma block and the width of a chroma block, the ratio being determined based on the color format of the current block, where, based on the color component of the current block being the chroma component, 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 between the height of the luma block and the height of the chroma block, the ratio being determined based on the color format of the current block.
8. Method of transmitting a bit stream generated by an image encoding method, the image encoding method comprising: determining a current block by dividing an image; generating an interpretation block from the current block; generating a residual block from the current block based on the interpretation block; and to encode information in the current block's interpretation mode in the bitstream, wherein the residual block is encoded based on the size of a transform block of the current block, CHARACTERIZED in that a maximum width and a maximum height of the transform block are determined separately based on a color component of the current block, wherein, based on the color component of the current block being a chroma component, the maximum width and maximum height of the transform block are determined based on a maximum size of a luma transform block corresponding to the current block and a color format of the current block, wherein, based on the color component of the current block being a chroma component, a position of an upper-left sample of the transform block is determined based on a position of an upper-left sample of a luma block corresponding to the current block and the color format of the current block, wherein, based on the color component of the current block being the chroma component, the maximum width of the transform block is derived by dividing the maximum size of the luma transform block corresponding to the current block. by a ratio between the width of a luma block and the width of a chroma block, the ratio being determined based on the color format of the current block, where, based on the color component of the current block being the chroma component, 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 between the height of the luma block and the height of the chroma block, the ratio being determined based on the color format of the current block.
9. Non-transient computer-readable recording medium that stores a bitstream generated by an image encoding method, the image encoding method comprising: determining a current block by splitting an image; generating an interpretation block from the current block; generating a residual block from the current block based on the interpretation block; and to encode information in the current block's interpretation mode in the bitstream, wherein the residual block is encoded based on the size of a transform block of the current block, CHARACTERIZED in that a maximum width and a maximum height of the transform block are determined separately based on a color component of the current block, wherein, based on the color component of the current block being a chroma component, the maximum width and maximum height of the transform block are determined based on a maximum size of a luma transform block corresponding to the current block and a color format of the current block, wherein, based on the color component of the current block being a chroma component, a position of an upper-left sample of the transform block is determined based on a position of an upper-left sample of a luma block corresponding to the current block and the color format of the current block, wherein, based on the color component of the current block being the chroma component, the maximum width of the transform block is derived by dividing the maximum size of the luma transform block corresponding to the block The current block is derived by a ratio between the width of a luma block and the width of a chroma block, the ratio being determined based on the color format of the current block, where, based on the color component of the current block being the chroma component, 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 between the height of the luma block and the height of the chroma block, the ratio being determined based on the color format of the current block.

Description

FIELD OF TECHNIQUE [001] This disclosure relates to a method and apparatus for image encoding/decoding and, more particularly, to a method and apparatus for encoding/decoding an image, limiting a maximum size of a chroma transform block, and a method for transmitting a bitstream generated by the image encoding method/apparatus of this disclosure. FUNDAMENTALS OF THE INVENTION [002] Recently, the demand for high-resolution, high-quality images, such as high-definition (HD) and ultra-high-definition (UHD) images, has been increasing in various fields. As the resolution and quality of image data improve, the amount of information or bits transmitted increases relatively compared to existing image data. An increase in the amount of information or bits transmitted causes an increase in transmission and storage costs. [003] Consequently, a highly efficient image compression technology is needed to efficiently transmit, store and reproduce information in high-resolution, high-quality images. Disclosure Technical Problem [004] One objective of the present disclosure is to provide an image encoding/decoding method and apparatus with improved encoding/decoding efficiency. [005] One objective of this disclosure is to provide an image encoding/decoding method and a device capable of improving encoding/decoding efficiency by limiting a maximum size of a chroma transform block. [006] Another objective of the present disclosure is to provide a method for transmitting a bit stream generated by an image encoding method or apparatus in accordance with the present disclosure. [007] Another object of the present disclosure is to provide a recording medium that stores a bitstream generated by an image encoding method or apparatus in accordance with the present disclosure. [008] Another objective of the present disclosure is to provide a recording medium that stores a received bit stream, which is decoded and used to reconstruct an image by an image decoding device in accordance with the present disclosure. [009] The technical problems solved by this disclosure are not limited to the technical problems described above, and other technical problems not described in this document will become apparent to those skilled in the art from the description that follows. Technical Solution [010] 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 interprediction mode information, based on the prediction mode of the current block being an interprediction 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. [011] An image decoding apparatus according to one 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 the information from the interprediction mode, based on the prediction mode of the current block being an interprediction 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. [012] An image coding method implemented by an image coding device according to an aspect of the present disclosure may include determining a current block by splitting an image, generating an interprediction block of the current block, generating a residual block of the current block based on the interprediction block, and encoding interprediction mode information of the current block. In this case, the residual block may be coded based on a transform block size of the current block and the transform block size may be determined based on a color component of the current block. [013] Furthermore, a transmission method according to another aspect of the present disclosure may transmit a bit stream generated by the picture encoding apparatus or the picture encoding method of the present disclosure. [014] 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. [015] The features briefly summarized above with respect to this disclosure are merely exemplary aspects of the detailed description below of this disclosure and do not limit the scope of this disclosure. Advantageous Effects [016] According to the present disclosure,