METHOD AND APPARATUS FOR IMAGE CODING BASED ON TRANSFORM

    公开(公告)号:US20220150503A1

    公开(公告)日:2022-05-12

    申请号:US17588075

    申请日:2022-01-28

    Abstract: An image decoding method according to the present document comprises the step of: deriving transform coefficients of a current block on the basis of residual information, wherein the residual information includes first flag information indicating whether a sub-block transform of splitting and transforming a coding unit is applied to the current block, and the step of deriving the transform coefficients comprises the step of, when the first flag information is 1, deriving a zero-out block indicating an area of the current block, in which a valid transform coefficient can exist, on the basis of whether a multiple transform selection (MTS) using multiple transform kernels is applied to the current block.

    Method for coding image on basis of secondary transform and device therefor

    公开(公告)号:US11297347B2

    公开(公告)日:2022-04-05

    申请号:US17327246

    申请日:2021-05-21

    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.

    Method and device for designing low complexity DST7

    公开(公告)号:US11290748B2

    公开(公告)日:2022-03-29

    申请号:US17058873

    申请日:2019-05-31

    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 32×32.

    Image coding method based on secondary transform, and device therefor

    公开(公告)号:US11290747B2

    公开(公告)日:2022-03-29

    申请号:US17327242

    申请日:2021-05-21

    Abstract: An image decoding method 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 a restoration picture on the basis of residual samples for the target block, on the basis of an inverse primary transform for the modified transform coefficients, wherein the inverse RST is performed on the basis of: transform sets determined by a mapping relation according to an intra prediction mode applied to the target block; and a transform kernel matrix selected from among two transform kernel matrices included in each of the transform sets, and is performed on the basis of: whether the inverse RST is applied; and a transform index for indicating any one of the transform kernel matrices included in the transform sets.

    Image coding method on basis of secondary transform and device therefor

    公开(公告)号:US11252420B2

    公开(公告)日:2022-02-15

    申请号:US16954026

    申请日:2018-12-13

    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.

    Intra prediction method and device in video coding system

    公开(公告)号:US10574984B2

    公开(公告)日:2020-02-25

    申请号:US15758967

    申请日:2016-08-25

    Abstract: An intra prediction method includes the steps of: acquiring intra prediction mode information from a bitstream; deriving neighboring samples of a current block; determining an intra prediction mode for the current block on the basis of the intra prediction mode information; deriving a prediction sample of the current block on the basis of the intra prediction mode and the neighboring samples; determining filtering reference samples for the prediction sample on the basis of the intra prediction mode; and deriving a filtered prediction sample by applying filtering to the prediction sample on the basis of the filtering reference samples. According to the present invention, a prediction sample can be adaptively filtered according to the intra prediction mode, and intra prediction performance can be improved.

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