# US 12,003,721 B2 · Image encoding/decoding method and apparatus using maximum transform size setting for chroma block, and method for transmitting bitstream > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,003,721 B2 - Document ID: US12003721B2 - Status: Granted - Kind: B2 - Application number: 18/209,665 - Filed: 2023-06-14 - Published: 2023-10-12 - Granted: 2024-06-04 - Earliest claimed: 2019-06-24 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Ling Li; Jung Hak Nam - Web page: https://patentgrep.com/patent/US12003721B2 ## CPC - H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks - H04N 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking - H04N 19/136: Incoming video signal characteristics or properties - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/593: involving spatial prediction techniques - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may include obtaining a current block by splitting an image, determining a prediction mode of the current block, generating an intra prediction block of the current block, based on the prediction mode of the current block being an intra prediction mode, generating a residual block of the current block, and reconstructing the current block based on the prediction block and the residual block of the current block. ## Claims ### Claim 1 An image decoding method performed by an image decoding apparatus, the image decoding method comprising: determining a prediction mode of a current block; generating an intra prediction block of the current block, based on the prediction mode of the current block being an intra prediction mode; and reconstructing the current block based on the intra prediction block, wherein the intra prediction block is generated based on a size of a transform block of the current block, wherein a maximum size of the transform block is separately determined for each of a width and a height of the transform block, wherein, based on a color component of the current block being a chroma component, the maximum size of the transform block is determined based on a color format of the current block, wherein the size of the transform block is determined based on a comparison result between the size of the transform block and the maximum size of the transform block, and wherein a top-left position of the transform block is determined based on a maximum width and a maximum height of the transform block. ### Claim 2 (depends on 1) The image decoding method of claim 1, wherein the maximum width of the transform block is determined based on a maximum size of a luma transform block corresponding to the current block and the color format of the current block. ### Claim 3 (depends on 1) The image decoding method of claim 1, wherein the maximum height of the transform block is determined based on a maximum size of a luma transform block corresponding to the current block and the color format of the current block. ### Claim 4 (depends on 1) The image decoding method of claim 1, wherein the current block is a chroma block, wherein, based on the width of the transform block being greater than the maximum width of the transform block, a plurality of lower-layer transform blocks are generated by vertically splitting the current block, and wherein the intra prediction block is generated for each of the plurality of lower-layer transform blocks. ### Claim 5 (depends on 4) The image decoding method of claim 4, wherein the plurality of lower-layer transform blocks include a first lower-layer transform block and a second lower-layer transform block, wherein a width of the first lower-layer transform block is determined to be half the width of the transform block, and wherein a top-left coordinate of the second lower-layer transform block is determined to be a value shifted from a top-left coordinate of the transform block to the right by half the width of the transform block. ### Claim 6 (depends on 1) The image decoding method of claim 1, wherein the current block is a chroma block, wherein, based on the height of the transform block being greater than the maximum height of the transform block, a plurality of lower-layer transform blocks are generated by horizontally splitting the current block, and wherein the intra prediction block is generated for each of the plurality of lower-layer transform blocks. ### Claim 7 (depends on 6) The image decoding method of claim 6, wherein the plurality of lower-layer transform blocks include a third lower-layer transform block and a fourth lower-layer transform block, wherein a height of the third lower-layer transform block is determined to be half the height of the transform block, and wherein a top-left coordinate of the fourth lower-layer transform block is determined to be a value shifted downward from a top-left coordinate of the transform block by half the height of the transform block. ### Claim 8 (depends on 1) The image decoding method of claim 1, wherein the maximum size of the transform block is 64×64 based on the color format of the current block being a 4:4:4 format, the maximum size of the transform block is 32×64 based on the color format of the current block being a 4:2:2 format, and the maximum size of the transform block is 32×32 based on the color format of the current block being a 4:2:0 format. ### Claim 9 An image encoding method performed by an image encoding apparatus, the image encoding method comprising: determining a prediction mode of a current block; generating an intra prediction block of the current block, based on the prediction mode of the current block being an intra prediction mode; and encoding the current block based on the intra prediction block, wherein the intra prediction block is generated based on a size of a transform block of the current block, wherein a maximum size of the transform block is separately determined for each of a width and a height of the transform block, wherein, based on a color component of the current block being a chroma component, the maximum size of the transform block is determined based on a color format of the current block, wherein the size of the transform block is determined based on a comparison result between the size of the transform block and the maximum size of the transform block, and wherein a top-left position of the transform block is determined based on a maximum width and a maximum height of the transform block. ### Claim 10 (depends on 9) A non-transitory computer-readable recording medium storing the bitstream generated by the image encoding method of claim 9. ### Claim 11 A method of transmitting a bitstream generated by an image encoding method, the image encoding method comprising: determining a prediction mode of a current block; generating an intra prediction block of the current block, based on the prediction mode of the current block being an intra prediction mode; and encoding the current block into the bitstream based on the intra prediction block, wherein the intra prediction block is generated based on a size of a transform block of the current block, wherein a maximum size of the transform block is separately determined for each of a width and a height of the transform block, wherein, based on a color component of the current block being a chroma component, the maximum size of the transform block is determined based on a color format of the current block, wherein the size of the transform block is determined based on a comparison result between the size of the transform block and the maximum size of the transform block, and wherein a top-left position of the transform block is determined based on a maximum width and a maximum height of the transform block.