Image coding method on basis of transformation and device therefor

    公开(公告)号:US11218731B2

    公开(公告)日:2022-01-04

    申请号:US16772934

    申请日:2018-12-13

    Abstract: 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.

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

    公开(公告)号:US11184618B2

    公开(公告)日:2021-11-23

    申请号:US16904985

    申请日:2020-06-18

    Abstract: A method for decoding an image by a decoding device according to the present invention comprises the steps of: deriving, from a bit stream, transform coefficients of a block to be decoded; deriving residual samples of the block to be decoded, on the basis of a selective transform of the transform coefficients; and generating a reconstructed picture on the basis of the residual samples of the block to be decoded and prediction samples of the block to be decoded, wherein the selective transform is performed on the basis of a modified transform matrix, the modified transform matrix comprises a matrix including a modified basis vector, and the modified basis vector contains a certain number of elements selected from N elements.

    Method for image coding on basis of separable transform and apparatus therefor

    公开(公告)号:US11166045B2

    公开(公告)日:2021-11-02

    申请号:US16652952

    申请日:2018-10-11

    Abstract: An image decoding method according to the present invention comprises the steps of: deriving, from a bitstream, quantized transform coefficients for a block to be decoded; deriving transform coefficients through dequantization on the basis of the quantized transform coefficients for the block to be decoded; determining a transform configuration group for the block to be decoded; deriving a horizontal transform kernel and a vertical transform kernel on the basis of the transform configuration group and transform index information acquired from the bitstream; deriving residual samples by performing a separable transform on the basis of the horizontal transform kernel and the vertical transform kernel; and generating a reconstructed picture on the basis of the residual samples and prediction samples of the block to be decoded, wherein the transform configuration group includes an identity transform kernel as a candidate transform kernel for the horizontal transform kernel or the vertical transform kernel. According to the present invention, the efficiency of residual coding can be improved.

    Method and apparatus for processing image signal

    公开(公告)号:US11146816B2

    公开(公告)日:2021-10-12

    申请号:US16899910

    申请日:2020-06-12

    Abstract: Embodiments of the present disclosure provide a method and device for processing a video signal. A method for decoding an image signal according to an embodiment of the present disclosure comprises the steps of: determining a non-separable transform set index indicating a non-separable transform set used for a non-separable transform of a current block from among non-separable transform sets predefined on the basis of an intra-prediction mode of the current block; determining. as a non-separable transform matrix, a transform kernel indicated by a non-separable transform index for the current block from among transform kernels included in the non-separable transform set indicated by the non-separable transform set index; and applying the non-separable transform matrix to an upper left region which of the current block, which is determined according to the width and height of the current block, wherein each of the predefined non-separable transform sets includes two transform kernels.

    Method and apparatus for processing image signal

    公开(公告)号:US11109028B2

    公开(公告)日:2021-08-31

    申请号:US17117785

    申请日:2020-12-10

    Abstract: Embodiments of the disclosure provide a method and apparatus for processing video signals. An image signal decoding method according to an embodiment of the disclosure comprises the steps of: determining, on the basis of the height and width of a current block, an input length and output length of a non-separable transform; determining a non-separable transform matrix corresponding to the input length and output length of the non-separable transform; and applying the non-separable transform matrix to the current block, wherein, when the height and width of the current block are 4 each, the input length and output length of the non-separable transform are determined to be 8 and 16 respectively.

    Method and apparatus for processing image signal

    公开(公告)号:US11082694B2

    公开(公告)日:2021-08-03

    申请号:US16901818

    申请日:2020-06-15

    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.

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