# US 12,003,774 B2 · Image coding method based on secondary transform, and device therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,003,774 B2 - Document ID: US12003774B2 - Status: Granted - Kind: B2 - Application number: 18/198,382 - Filed: 2023-05-17 - Published: 2023-10-26 - Granted: 2024-06-04 - Earliest claimed: 2018-12-18 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Moonmo Koo; Seunghwan Kim; Jaehyun Lim - Web page: https://patentgrep.com/patent/US12003774B2 ## 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 19/61: in combination with predictive coding - H04N 19/11: among a plurality of spatial predictive coding modes - H04N 19/124: Quantisation - 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 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/167: Position within a video image, e.g. region of interest [ROI] - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/18: the unit being a set of transform coefficients - H04N 19/593: involving spatial prediction techniques - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image decoding method according to the present document comprises the steps of: deriving transform coefficients through inverse quantization on the basis of quantized transform coefficients for a target block; deriving modified transform coefficients on the basis of an inverse reduced secondary transform (RST) for the transform coefficients; and generating, on the basis of an inverse primary transform for the modified transform coefficients, a restoration picture based on residual samples for the target block, wherein the modified transform coefficients derived according to the inverse RST are two-dimensionally arranged according to the order of a row priority direction or a column priority direction according to an intra prediction mode to be applied to the target block. ## Claims ### Claim 1 An image decoding method performed by a decoding apparatus, the method comprising: obtaining residual information from a bitstream; deriving quantized transform coefficients for a target block based on the residual information; deriving transform coefficients for the target block by dequantizing the quantized transform coefficients; deriving modified transform coefficients for the target block based on an inverse non-separable transform for the transform coefficients; deriving residual samples for the target block based on an inverse primary transform for the modified transform coefficients; and generating a reconstructed picture based on the residual samples for the target block, wherein the inverse non-separable transform is performed through a matrix operation of the transform coefficients for a top-left area of the target block and a transform kernel matrix, wherein a larger number of the modified transform coefficients than the transform coefficients are derived through the matrix operation, wherein the modified transform coefficients are two-dimensionally arranged according to a row-first direction based on an intra prediction mode applied to the target block being a horizontal mode in a left direction with respect to a top-left diagonal direction, and wherein the modified transform coefficients are two-dimensionally arranged according to a column-first direction based on the intra prediction mode applied to the target block being a vertical mode in a right direction with respect to the top-left diagonal direction. ### Claim 2 An image encoding method performed by an encoding apparatus, the method comprising: deriving residual samples for a target block; deriving transform coefficients for the target block based on a primary transform for the residual samples; deriving modified transform coefficients for the target block based on a non-separable transform for the transform coefficients; deriving quantized transform coefficients for the target block by quantizing the modified transform coefficients; and encoding residual information based on the quantized transform coefficients, wherein the non-separable transform is performed through a matrix operation of the transform coefficients for a top-left area of the target block and a transform kernel matrix, wherein a smaller number of the modified transform coefficients than the transform coefficients are derived through the matrix operation, wherein the transform coefficients are one-dimensionally arranged according to a row-first direction based on an intra prediction mode applied to the target block being a horizontal mode in a left direction with respect to a top-left diagonal direction, and wherein the transform coefficients are one-dimensionally arranged according to a column-first direction based on the intra prediction mode applied to the target block being a vertical mode in a right direction with respect to the top-left diagonal direction. ### Claim 3 (depends on 2) A non-transitory computer readable storage medium storing a bitstream generated by the image encoding method of the claim 2. ### Claim 4 A transmission method of data for an image, the method comprising: obtaining a bitstream for the image, wherein the bitstream is generated based on deriving residual samples for a target block, deriving transform coefficients for the target block based on a primary transform for the residual samples, deriving modified transform coefficients for the target block based on a non-separable transform for the transform coefficients, deriving quantized transform coefficients for the target block by quantizing the modified transform coefficients, and encoding residual information based on the quantized transform coefficients; and transmitting the data comprising the bitstream, wherein the non-separable transform is performed through a matrix operation of the transform coefficients for a top-left area of the target block and a transform kernel matrix, wherein a smaller number of the modified transform coefficients than the transform coefficients are derived through the matrix operation, wherein the transform coefficients are one-dimensionally arranged according to a row-first direction based on an intra prediction mode applied to the target block being a horizontal mode in a left direction with respect to a top-left diagonal direction, and wherein the transform coefficients are one-dimensionally arranged according to a column-first direction based on the intra prediction mode applied to the target block being a vertical mode in a right direction with respect to the top-left diagonal direction.