# US 12,003,772 B2 · Method and apparatus for encoding/decoding residual data based on a plurality of transformations > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,003,772 B2 - Document ID: US12003772B2 - Status: Granted - Kind: B2 - Application number: 17/970,214 - Filed: 2022-10-20 - Published: 2023-02-09 - Granted: 2024-06-04 - Earliest claimed: 2018-06-08 - Assignees: Kt Corporation - Applicants: Kt Corporation - Inventors: Bae Keun Lee - Web page: https://patentgrep.com/patent/US12003772B2 ## CPC - H04N 19/12: Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264 - H04N 19/60: using transform coding - 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 19/157: Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/88: involving rearrangement of data among different coding units, e.g. shuffling, interleaving, scrambling or permutation of pixel data or permutation of transform coefficient data among different blocks - H04N 19/11: among a plurality of spatial predictive coding modes - H04N 19/122: Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type - H04N 19/593: involving spatial prediction techniques - H04N 19/96: Tree coding, e.g. quad-tree coding - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image decoding method according to the present invention can comprise the steps of: acquiring residual coefficients of a current block; dequantizing the residual coefficients; performing secondary inverse transformation on the dequantized residual coefficients; and performing primary inverse transformation on the performance result of the secondary inverse transformation. The secondary inverse transformation can be performed for a partial region of the current block. ## Claims ### Claim 1 A method of decoding an image, comprising: determining a horizontal transform type and a vertical transform type of a current block from a transform set including two transform type candidates; and performing an inverse-transform on the current block based on the horizontal transform type and the vertical transform type, wherein the horizontal transform type is determined based on whether a width of the current block is in a predefined range, wherein the vertical transform type is determined based on whether a height of the current block is in the predefined range, wherein when the current block has a square shape, in which the width and the height are the same, the horizontal transform type and the vertical transform type are mutually the same, and wherein when the current block has a non-square shape, in which the width is in the predefined range while the height is not in the predefined range, the horizontal transform type and the vertical transform type are different from each other. ### Claim 2 (depends on 1) The method of claim 1, wherein the pre-defined range is defined as a range of 4 to 16. ### Claim 3 (depends on 1) The method of claim 1, wherein one of the two transform type candidates is representative of one of DCT-II or DST-VII and the other of the two transform type candidates is representative of the other of DCT-II or DST-VII. ### Claim 4 A method of encoding an image, comprising: determining a horizontal transform type and a vertical transform type of a current block from a transform set including two transform type candidates; and performing a transform on the current block based on the horizontal transform type and the vertical transform type, wherein the horizontal transform type is determined based on whether a width of the current block is in a predefined range, wherein the vertical transform type is determined based on whether a height of the current block is in the predefined range, wherein when the current block has a square shape, in which the width and the height are the same, the horizontal transform type and the vertical transform type are mutually the same, and wherein when the current block has a non-square shape, in which the width is in the predefined range while the height is not in the predefined range, the horizontal transform type and the vertical transform type are different from each other. ### Claim 5 A method for transmitting a bitstream generated by an encoding method, the encoding method comprising: determining a transform set of a current block in the image among a plurality of transform sets, each of the plurality of transform sets including one or more transform type candidates available for the current block, the transform set of the current block being determined based on index information encoded for the current block; determining a horizontal transform type and a vertical transform type of a current block from a transform set including two transform type candidates; and performing a transform on the current block based on the horizontal transform type and the vertical transform type to generate the bitstream, wherein the horizontal transform type is determined based on whether a width of the current block is in a predefined range, wherein the vertical transform type is determined based on whether a height of the current block is in the predefined range, wherein when the current block has a square shape, in which the width and the height are the same, the horizontal transform type and the vertical transform type are mutually the same, and wherein when the current block has a non-square shape, in which the width is in the predefined range while the height is not in the predefined range, the horizontal transform type and the vertical transform type are different from each other. ### Claim 6 (depends on 1) The method of claim 1, wherein a prediction mode of the current block is intra prediction. ### Claim 7 (depends on 1) The method of claim 1, wherein whether to decode index information from a bitstream to determine the transform set of the current block is determined based on a partition type of a coding block including the current block.