Image coding method based on transform, and device for same

    公开(公告)号:US11765389B2

    公开(公告)日:2023-09-19

    申请号:US17985577

    申请日:2022-11-11

    摘要: An image decoding method according to the present document may include the steps of: deriving the position of the final significant coefficient in the current block and transform coefficients for the current block on the basis of residual information; determining whether the index of a sub-block including the final significant coefficient is 0 and whether the position of the final significant coefficient in the sub-block is greater than 0; determining whether a significant coefficient exists in a second area excluding a first area at the upper left end of the current block; and parsing an LFNST index from a bitstream when the position of the final significant coefficient is determined to be greater than 0 in the sub-block in which the index is 0, and the significant coefficient does not exist in the second area.

    TRANSFORM-BASED IMAGE CODING METHOD AND DEVICE THEREFOR

    公开(公告)号:US20230239563A1

    公开(公告)日:2023-07-27

    申请号:US18128132

    申请日:2023-03-29

    IPC分类号: H04N19/00 G06F9/48

    摘要: An image decoding method according to the present document comprises a step of deriving a corrected transform coefficient, wherein the step of deriving the corrected transform coefficient comprises the steps of: determining whether LFNST can be applied to the height and width of a divided sub-partition block when an ISP is applied to a current block; parsing a LFNST index when the LFNST can be applied; and deriving the corrected transform coefficient on the basis of the LFNST index and a LFNST matrix.

    Modified transform-based image coding method and device for same

    公开(公告)号:US11700377B2

    公开(公告)日:2023-07-11

    申请号:US17535095

    申请日:2021-11-24

    摘要: 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.

    Method and apparatus for coding image on basis of transform

    公开(公告)号:US11611776B2

    公开(公告)日:2023-03-21

    申请号:US17572282

    申请日:2022-01-10

    摘要: An image decoding method according to the present document may comprise the steps of: deriving a first variable indicating whether there is a valid coefficient in a region excluding a DC region from a current block; deriving a second variable indicating whether there is a valid coefficient in a second region excluding a first region formed at the upper left end of the current block; when the first variable indicates that the valid coefficient exists in the region excluding the DC region, and the second variable indicates that the valid coefficient does not exist in the second region, parsing an LFNST index from the bitstream; and applying an LFNST matrix derived on the basis of the LFNST index to transform coefficients in the first region, to derive the modified transform coefficients.

    Image coding method on basis of transformation and device therefor

    公开(公告)号:US11601679B2

    公开(公告)日:2023-03-07

    申请号:US17507446

    申请日:2021-10-21

    摘要: An image decoding method performed by means of a decoding device according to the present invention comprises the steps of: deriving quantized transform coefficients with respect to a target block from a bitstream; performing inverse quantization with respect to the quantized transform coefficients with respect to the target block and deriving transform coefficients; deriving residual samples with respect to the target block on the basis of reduced inverse transform with respect to the transform coefficients; and generating a reconstructed picture on the basis of the residual samples with respect to the target block and prediction samples with respect to the target block. The reduced inverse transform is performed on the basis of a reduced inverse transform matrix. The reduced inverse transform matrix is a non-square matrix of which the number of columns is smaller than the number of rows.

    Transform-based image coding method and device therefor

    公开(公告)号:US11595691B2

    公开(公告)日:2023-02-28

    申请号:US17727516

    申请日:2022-04-22

    摘要: An image decoding method according to the present document comprises the steps of: updating an intra-prediction mode of a chroma block on the basis of an intra-prediction mode of a luma block corresponding to the chroma block on the basis of the intra-prediction mode of the chroma block being a cross-component linear model (CCLM) mode; and determining a LFNST set including LFNST matrixes on the basis of the updated intra-prediction mode, wherein the updated intra-prediction mode is derived as an intra-prediction mode corresponding to a specific position in the luma block, and the updated intra-prediction mode is updated as an intra-DC mode on the basis of the intra-prediction mode, that corresponds to the specific position, being an intra-block copy (IBC) mode.