Abstract: An image decoding method according to the present document comprises the steps of: on the basis of an intra prediction mode of a chroma block being a cross-component linear model (CCLM) mode and an intra prediction mode of a luma block corresponding to the chroma block being a palette mode, updating the intra prediction mode of the chroma block to an intra DC mode; on the basis of the updated intra prediction mode, determining an LFNST set including LFNST matrices; and performing LFNST on the chroma block on the basis of an LFNST matrix derived from the LFNST set, wherein the intra DC mode is an intra prediction mode corresponding to a specific location within the luma block.

Abstract: An image decoding method and device according to the present disclosure derive transform coefficients of the current block from a bitstream, perform inverse quantization and/or inverse transformation on the transform coefficients of the current block so as to derive residual samples of the current block, and can reconstruct the current block on the basis of the residual samples of the current block. Here, inverse transformation can be performed on the basis of a non-separable primary inverse transform kernel and/or a trigonometric function-based primary transform kernel.

Abstract: An image decoding method and apparatus according to the present disclosure may configure a transform set for the current block, determine a transform kernel of the current block from the transform set on the basis of a transform kernel candidate index indicating any one of a plurality of transform kernel candidates, derive a residual sample of the current block by performing inverse transformation on the current block on the basis of the transform kernel of the current block, and reconstruct the current block on the basis of the residual sample of the current block.

Abstract: An image decoding method and device according to the present disclosure derive transform coefficients of the current block from a bitstream, perform inverse quantization and/or inverse transformation on the transform coefficients of the current block so as to derive residual samples of the current block, and can reconstruct the current block on the basis of the residual samples of the current block. Here, inverse transformation can be performed on the basis of a non-separable primary inverse transform kernel.

Abstract: An image decoding method and device, according to the present disclosure, may: derive a transform coefficient of a current block from a bitstream; derive residual samples of the current block by performing at least one of inverse quantization or inverse transformation on the transform coefficient of the current block; and restore the current block on the basis of the residual samples of the current block.

Abstract: The embodiments of the present disclosure provides a method and apparatus for video signal processing. A method for decoding an image signal according to an embodiment of the present disclosure may include determining an input length and an output length of a non-separable transform based on a height and a width of a current block; determining a non-separable transform matrix corresponding to the input length and the output length of a non-separable transform; and applying the non-separable transform matrix to coefficients by a number of the input length in the current block, wherein the height and the width of a current block is greater than or equal to 8, wherein, if each of the height and the width of a current block is equal to 8, the input length of the non-separable transform is determined as 8.

Abstract: An image decoding method according to the present document is characterized by including: a step for receiving a bitstream including residual information; a step for deriving transform coefficients for a target block on the basis of the residual information; a step for deriving corrected transform coefficients on the basis of an inverse non-separable transform of the transform coefficients; and a step for deriving residual samples for the target block on the basis of an inverse primary transform of the corrected transform coefficients, wherein the inverse non-separable transform is performed when the size of the target block is equal to or smaller than the size of a prescribed maximum transform application block.

Abstract: An image decoding method according to the present document comprises the steps of: receiving image information including residual information for a current block; and generating residual samples of the current block on the basis of the residual information, wherein the residual information includes information on transform coefficients of the current block, and the residual samples are generated from the information on the transform coefficients on the basis of low-frequency non-separable transform (LFNST) index information.

Abstract: An image decoding method according to the present document comprises: a residual coding step for parsing residual information received in a residual coding level and arranging transform coefficients for a current block according to a predetermined scanning order; a step for deriving residual samples by applying at least one of LFNST or MTS to the transform coefficients; and a step for generating a reconstructed picture on the basis of the residual samples, wherein the LFNST is performed on the basis of an LFNST index indicating an LFNST kernel, the MTS is performed on the basis of an MTS index indicating an MTS kernel, the LFNST index and the MTS index are signaled in a coding unit level, and the MTS index is signaled immediately after the signaling of the LFNST index.

Abstract: An image decoding method and device according to the present disclosure can acquire residual information from a bitstream, derive transform coefficients of a current block on the basis of the residual information, derive residual samples of the current block by performing at least one of inverse quantization or inverse transform on the transform coefficients of the current block, and restore the current block on the basis of the residual samples of the current block. Here, the inverse transform can be performed on the basis of at least one of non-separable transform or separable transform. A non-separable transform set for the non-separable transform can be determined on the basis of a mapping table defining mapping relationships between pre-defined intraprediction modes and non-separable transform sets.

Abstract: This image decoding method and device according to the present disclosure can: acquire residual information from a bitstream; derive transform coefficients of the current block on the basis of the residual information; derive residual samples of the current block by performing inverse transform on transform coefficients of the current block; and reconstruct the current block on the basis of the residual samples of the current block. Here, the inverse transform is performed on the basis of at least one from among a non-split primary transform, a non-split secondary transform and a split primary transform, and the non-split primary transform can be applied on the basis of the size of the current block.

Abstract: An image decoding method according to this document comprises a step for deriving, for transform coefficients, modified transform coefficients on the basis of inverse secondary transformation, wherein the step for deriving the modified transform coefficients comprises a step for deriving a transform kernel to be applied to the inverse secondary transformation, the transform kernel may be derived as a 16×16 matrix on the basis of horizontal and vertical lengths of a target block being both greater than or equal to 4 and the horizontal or vertical length being 4, and the transform kernel may be derived as a 48×16 matrix on the basis of the horizontal and vertical lengths of the target block being both greater than or equal to 8 and the horizontal or vertical length being 8.

Abstract: An image decoding method according to the present document may comprise: a step of deriving transform coefficients for a current block by performing inverse quantization on the basis of residual information; and a step of deriving modified transform coefficients by applying LFNST to the transform coefficients, wherein the step of deriving the transform coefficients comprises a step of parsing position information of a last non-zero transform coefficient, an LFNST index related to application of the LFNST is parsed after parsing a position of the last non-zero transform coefficient, and the transform coefficients are derived after parsing the LFNST index.

Abstract: An image decoding method according to the present document comprises a step of deriving modified transform coefficients on the basis of an inverse reduced secondary transform (RST) regarding transform coefficients regarding a target block. The inverse RST is performed on the basis of transform sets determined on the basis of a mapping relation following an intra prediction mode applied to the target block, and a transform kernel matrix selected from two transform kernel matrices included in the transform sets, respectively, and and is performed on the basis of whether or not the inverse RST is applied, and a transform index indicating one of the transform kernel matrices included in the transform sets. A syntax element bin string regarding the transform index is decoded on the basis of a different context set according to the tree type regarding the division structure of the target block.

Abstract: An image decoding method and apparatus according to the present disclosure may: acquire residual information from a bitstream; derive transform coefficients of the current block on the basis of the residual information; derive residual samples of the current block by performing at least one of dequantization and inverse transform on the transform coefficients of the current block; and reconstruct the current block on the basis of the residual samples of the current block. Here, the inverse transform may be performed on the basis of at least one of a non-separable primary transform, a low-frequency non-separable transform, and a separable primary transform.

Abstract: An image decoding method according to the present document can comprise the steps of: acquiring, from a bitstream, intra prediction mode information and an LFNST index; deriving, as a cross-component linear model (CCLM) mode, an intra prediction mode of a chroma block on the basis of the intra prediction mode information; changing the intra prediction mode of the chroma block from the CCLM mode to an intra prediction mode of a luma block corresponding to the chroma block; determining an LFNST set, including LFNST matrices, on the basis of the intra prediction mode of the luma block; selecting one of the LFNST matrices on the basis of the LFNST set and the LFNST index; and deriving transform coefficients for the chroma block on the basis of the selected LFNST matrix.

Abstract: An image decoding method according to the present document comprises the step of deriving modified transform coefficients by applying LFNST to transform coefficients, wherein the step of deriving the modified transform coefficients comprises the steps of: deriving a variable indicating whether an effective coefficient is present in a DC component of a current block; and parsing an LFNST index on the basis of whether the variable indicates that the effective coefficient is present in a position other than the DC component, wherein the variable may be derived on the basis of an individual transform skip flag value for a color component of the current block.

Abstract: According to the disclosure of the present disclosure: an LFNST set index for a current block may be derived on the basis of an intra prediction mode; on the basis of the intra prediction mode for the current block being a WAIP mode, the LFNST set index may be derived as predetermined one value; and on the basis of the intra prediction mode for the current block being an NAIP mode, the LFNST set index may be derived as one of predetermined N values. Accordingly, it is possible to maximize the coding performance that can be brought about by LFNST within the implementation complexity allowed by a next standard.

Abstract: An image decoding method and apparatus according to the present disclosure may comprise: obtaining residual information from a bitstream; deriving transform coefficients of a current block on the basis of the residual information; performing at least one of inverse quantization or inverse transform on the transform coefficients of the current block and deriving residual samples of the current block; and reconstructing the current block on the basis of the residual samples of the current block. In this case, the inverse transform is performed on the basis of a non-separable primary transform, and the non-separable primary transform may be applied on the basis of at least one of the size of a current block, a tree type, and a component type.

Abstract: An image decoding method according to the present document can comprise the steps of: deriving a transform coefficient for a current block on the basis of residual information; determining whether an effective coefficient is in a second area that excludes the upper left first area of the current block; parsing an MTS index from a bitstream if the effective coefficient is not in the second area; and deriving a residual sample by applying, to transform coefficients of the first area, an MTS kernel derived on the basis of the MTS index.