Abstract: Reconstructing a video signal based on low-complexity DST7 design including obtaining a transform index of a current block from the video signal and deriving a transform combination corresponding to the transform index. The transform index corresponds to any one of a plurality of transform combinations including a combination of DST7 and/or DCT8, and the transform combination includes horizontal and vertical transforms that correspond to at least one of the DST7 or the DCT8. The reconstruction also includes performing an inverse transform in a vertical direction by using the DST7, performing an inverse transform in a horizontal direction by using the DCT8, and reconstructing the video signal by using the current block on which the inverse transform is performed. The DST7 includes Discrete Fourier Transform (DFT) and has a different type of DFT structure based on a size of the current block.

Abstract: Provided is a method for decoding a video signal based on a reduced transform, which includes: checking whether a transform skip is applied to a current block; obtaining a transform index indicating a transform kernel of the current block from the video signal when the transform skip is not applied to the current block; determining a region where a primary transform is applied to the current block based on the transform kernel indicated by the transform index and a size of the current block; and performing an inverse primary transform on the region to which the primary transform is applied by using the transform kernel indicated by the transform index.

Abstract: The present disclosure, in a method of decoding a video signal, provides a method including checking whether a transform skip is applied to a current block; acquiring a transform index indicating transform types applied to a horizontal direction and a vertical direction of the current block from among a plurality of predefined transform types from the video signal when the transform skip is not applied to the current block; and performing an inverse primary transform on the current block using the transform types indicated by the transform index, wherein the transform types applied to the horizontal direction and the vertical direction of the current block are determined from among transform types defined according to an intra prediction mode of the current block based on the transform index.

Abstract: The present invention relates to a video signal decoding method based on a Multiple Transform Selection (MTS).

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: The present invention provides a method for reconstructing a video signal by using an approximation transform on the basis of a preprocessing/postprocessing matrix, the method comprising: obtaining a transform index of a current block from a video signal, wherein the transform index corresponds to any one of a plurality of transform combinations including at least one of DST7, DCT8, DST6, or flipped DST7, and a transform combination includes a horizontal transform and a vertical transform; deriving a primary transform for horizontal/vertical directions corresponding to the transform index; performing an inverse primary approximation transform by using the primary transform for the horizontal/vertical directions, wherein the inverse primary approximation transform is generated by multiplying the primary transform for the horizontal/vertical directions by a preprocessing matrix and a postprocessing matrix; and reconstructing the video signal by using the inverse primary approximation-transformed current block.

Abstract: Embodiments of the present specification provide a method and a device for processing motion vector difference (MVD) information for inter prediction in a video signal. A method for decoding MVD information, according to one embodiment of the present specification, comprises the steps of: acquiring a first flag indicating whether a MVD for predicting the current block is greater than a first value; on the basis of the first flag, acquiring a second flag indicating whether the MVD is greater than a second value; and decoding size information of the MVD on the basis of the second flag, wherein a step for acquiring the size information of the MVD comprises a step for, if the MVD is equal to or smaller than the second value, decoding the size information of the MVD on the basis of a first difference value which corresponds to the difference between the second value and the first value.

Abstract: A method for decoding a video signal based on reduced transform includes the steps of: obtaining, from the video signal, a transform index indicating transform kernels applied to horizontal and vertical directions of a current block; determining a region in which a transform is applied to the current block based on the transform kernels indicated by the transform index and a size of the current block; deriving, as zero, coefficients of a remaining region other than the region to which the transform is applied within the current block; and performing an inverse transform on the region to which the transform is applied using the transform kernels indicated by the transform index.

Abstract: An image information decoding method performed by means of a decoding device according to the present invention comprises the steps of: decoding a non-separable secondary transform (NSST) index from a bitstream if NSST is applied to a target block; decoding information relating to transform coefficients with respect to the target block from the bitstream on the basis of the decoded NSST index; and deriving the transform coefficients with respect to the target block on the basis of the decoded information relating to the transform coefficients, wherein the NSST index is decoded prior to the information relating to the transform coefficients with respect to the target block.

Abstract: An image decoding method according to the present disclosure includes deriving transform coefficients through dequantization based on the quantized transform coefficients for the target block; deriving modified transform coefficients based on an inverse reduced secondary transform (RST) 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 samples based on the residual samples, and prediction samples derived based on an intra prediction mode for the target block, wherein the inverse RST is performed based on a transform kernel matrix selected from a transform set including a plurality of transform kernel matrices, the transform set is determined based on a mapping relationship according to the intra prediction mode applied to the target block, and a plurality of intra prediction modes including the intra prediction mode of the target block are mapped to one transform set.

Abstract: A method for decoding an image by a decoding apparatus according to the present disclosure comprises the steps of: acquiring intra prediction mode information of a current block; rearranging the remaining intra prediction modes on the basis of a lookup table; deriving a subgroup of the current block on the basis of subgroup information; decoding remaining intra prediction mode information on the basis of a binarization method for the subgroup; deriving, as an intra prediction mode of the current block, an intra prediction mode indicated by the decoded remaining intra prediction mode information among the intra prediction modes included in the subgroup; and generating a prediction sample of the current block on the basis of the intra prediction mode.

Abstract: A method and device for processing a video signal using a reduced transform are provided. A method for decoding a video signal includes splitting a current block into a plurality of subblocks based on a first flag for a split direction of the current block, determining a subblock, to which a transform is applied, among the plurality of subblocks based on a second flag for a position of a transform target block, determining a transform target area in the subblock, and applying an inverse transform including a horizontal transform and a vertical transform to transform coefficients of the transform target area. The transform target area is determined based on a transform type applied to the subblock and a size of the subblock.

Abstract: Disclosed is a method for encoding/decoding video signals and an apparatus therefor. Specifically, a method for decoding a video signal based on reduced transform comprised the steps of: obtaining, from the video signal, a transform index indicating transform kernels applied to horizontal and vertical directions of a current block; determining a region in which a transform is applied to the current block based on the transform kernels indicated by the transform index and a size of the current block; deriving, as zero, coefficients of a remaining region other than the region to which the transform is applied within the current block; and performing an inverse transform on the region to which the transform is applied using the transform kernels indicated by the transform index.

Abstract: Embodiments in the present specification provide a method and device for processing video signal by using a sub-block unit transform.

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 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: A video decoding method according to the present document comprises the steps of: deriving transform coefficients by performing de-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) of the transform coefficients; and generating a reconstructed picture on the basis of residual samples for the target block on the basis of an inverse primary transform of the modified transform coefficients, wherein an inverse RST using a transform kernel matrix is performed on transform coefficients of an upper-left 4×4 region of an 8×8 region of the target block, and modified transform coefficients of the upper-left 4×4 region, an upper-right 4×4 region, and a lower-left 4×4 region of the 8×8 region are derived through the inverse RST.

Abstract: The present disclosure provides a method for reconstructing a video signal through a low-complexity Discrete Sine Transform-7 (DST7) design, including: obtaining a transform index of a current block from the video signal, wherein the transform index corresponds to any one of a plurality of transform combinations including combinations of DST7 and/or a Discrete Cosine Transform-8 (DCT8); deriving a transform combination corresponding to the transform index, wherein the transform combination includes a horizontal transform and a vertical transform, and wherein the horizontal transform and the vertical transform correspond to any one of the DST7 and the DCT8; performing an inverse transform on the current block in a vertical or horizontal direction using the DST7 or the DCT8; and reconstructing the video signal using the inverse transformed current block, wherein a 33-point Discrete Fourier Transform (DFT) is applied to the DST7 when the DST7 is 16×16 and a 65-point DFT is applied to the DST7 when the DST7 is 32

Abstract: Provided is a method for decoding a video signal based on a reduced transform, which includes: checking whether a transform skip is applied to a current block; obtaining a transform index indicating a transform kernel of the current block from the video signal when the transform skip is not applied to the current block; determining a region where a primary transform is applied to the current block based on the transform kernel indicated by the transform index and a size of the current block; and performing an inverse primary transform on the region to which the primary transform is applied by using the transform kernel indicated by the transform index.

Abstract: An image decoding method according to the present document can comprise the steps of: on the basis of first flag information indicating whether or not matrix-based intra prediction (MIP) can be applied to a current block, receiving second flag information indicating whether or not the MIP is used for the current block; receiving matrix-based intra prediction (MIP) mode information on the basis of the second flag information; generating intra prediction samples for the current block on the basis of the MIP mode information; and generating reconstructed samples for the current block on the basis of the intra prediction samples.

Abstract: An image decoding method according to the present document can comprise the steps of: receiving flag information indicating whether a matrix-based intra prediction (MIP) is used with respect to a current block; receiving matrix-based intra prediction (MIP) mode information on the basis of the flag information; generating an intra prediction sample for the current block on the basis of the MIP mode information; and generating restoration samples for the current block on the basis of the intra prediction samples.