Transform-based image coding method and device therefor

    公开(公告)号:US11882289B2

    公开(公告)日:2024-01-23

    申请号:US17894745

    申请日:2022-08-24

    CPC classification number: H04N19/132 H04N19/105 H04N19/176 H04N19/18

    Abstract: An image decoding method, according to the present document, may comprise the steps of: deriving transform coefficients for a current block on the basis of residual information; determining whether a significant coefficient is present in a second region excluding a first region in the top-left end of the current block; parsing a LFNST index from a bitstream if the significant coefficient is not present in the second region; deriving modified transform coefficients by applying a LFNST matrix, derived on the basis of the LFNST index, to transform coefficients of the first region; and deriving residual samples of the current block on the basis of an inverse primary transform of the modified transform coefficients.

    Image coding method and device on basis of wide-angle intra prediction and transform

    公开(公告)号:US11641471B2

    公开(公告)日:2023-05-02

    申请号:US17610985

    申请日:2020-05-27

    Abstract: An image decoding method according to the present document comprises the steps of: obtaining intra prediction mode information and an LFNST index; deriving an intra prediction mode of a current block on the basis of intra prediction mode information; when wide-angle intra prediction is applied to the current block, deriving a modified intra prediction mode by means of intra prediction mode remapping; deciding an LFNST set comprising LFNST matrices on the basis of the modified intra prediction mode; selecting one of the LFNST matrices on the basis of the LFNST set and LFNST index; and deriving transform coefficients for the current block on the basis of the selected LFNST matrix.

    Video coding method on basis of secondary transform, and device for same

    公开(公告)号:US11582486B2

    公开(公告)日:2023-02-14

    申请号:US17592768

    申请日:2022-02-04

    Abstract: A video decoding method according to the present document is characterized by comprising: a step for deriving transform coefficients through inverse quantization on the basis of quantized transform coefficients for a target block; a step for deriving modified transform coefficients on the basis of an inverse reduced secondary transform (RST) of the transform coefficients; and a step for 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 the inverse RST using a transform kernel matrix is performed on transform coefficients of the upper-left 4×4 region of an 8×8 region of the target block, and the modified transform coefficients of the upper-left 4×4 region, upper-right 4×4 region, and lower-left 4×4 region of the 8×8 region are derived through the inverse RST.

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