CCLM PREDICTION-BASED IMAGE DECODING METHOD AND APPARATUS IN IMAGE CODING SYSTEM

    公开(公告)号:US20220150538A1

    公开(公告)日:2022-05-12

    申请号:US17432372

    申请日:2020-02-21

    Abstract: An image decoding method executed by a decoding apparatus according to the present document comprises the steps of: deriving an intra prediction mode of the current chroma block by means of cross-component linear model (CCLM) mode; deriving downsampled luma samples on the basis of the current luma block; deriving downsampled neighboring luma samples on the basis of neighboring luma samples of the current luma block; and deriving the CCLM parameter on the basis of the downsampled neighboring luma samples and neighboring chroma samples of the current neighboring chroma block, wherein the number of downsampled neighboring luma samples and number of neighboring chroma samples are equal to the previously set thresh-hold value, and the thresh-hold value is derived on the basis of the width and height of the current chroma block.

    IMAGE DECODING METHOD FOR RESIDUAL CODING AND APPARATUS THEREFOR

    公开(公告)号:US20220132132A1

    公开(公告)日:2022-04-28

    申请号:US17569346

    申请日:2022-01-05

    Abstract: An image decoding method performed by a decoding apparatus, according to the present document, comprises the steps of: acquiring image information including prediction mode information and a residual coding flag; deriving a prediction sample of a current block on the basis of the prediction mode information; on the basis of the residual coding flag, determining whether or not a transform skip residual coding syntax structure is available for the current block within a current slice; deriving a residual sample of the current block by parsing syntax elements for the current block on the basis of a result of the determination; and generating a reconstructed picture on the basis of the prediction sample and the residual sample.

    UNIFIED MPM LIST-BASED INTRA PREDICTION

    公开(公告)号:US20220124309A1

    公开(公告)日:2022-04-21

    申请号:US17431659

    申请日:2020-02-28

    Abstract: An image decoding method according to the present document comprises the steps of: obtaining, from a bitstream, subpartition mode information indicating whether sub-partition intra prediction is used for a current block; configuring an MPM list including candidate intra prediction modes for deriving an intra prediction mode of the current block; deriving the intra prediction mode of the current block from among the candidate intra prediction modes included in the MPM list on the basis of MPM index information; generating prediction samples for the current block on the basis of the intra prediction mode; and generating reconstructed samples for the current block on the basis of the prediction samples, wherein one of the candidate intra prediction modes in the MPM list is a DC mode, based on the sub-partition mode information indicating that the sub-partition intra prediction is used for the current block.

    BDPCM-BASED IMAGE DECODING METHOD AND DEVICE FOR SAME

    公开(公告)号:US20220078433A1

    公开(公告)日:2022-03-10

    申请号:US17424347

    申请日:2020-06-17

    Abstract: An image decoding method performed by a decoding device according to the present document is characterized by including: a step for determining whether the width and height of the current block are smaller than or equal to a maximum transform block size; a step for acquiring a Block-based Delta Pulse Code Modulation (BDPCM) flag, which indicates whether to apply BDPCM to the current block, when the width and height are smaller than or equal to the maximum transform block size; a step for acquiring a BDPCM direction flag that indicates a prediction direction for the current block on the basis of the BDPCM flag; a step for deriving prediction samples of the current block on the basis of an intra-prediction mode derived on the basis of the BDPCM direction flag; and a step for deriving recovered samples of the current block on the basis of the prediction samples.

    CCLM-BASED INTRA-PREDICTION METHOD AND APPARATUS THEREFOR

    公开(公告)号:US20220038683A1

    公开(公告)日:2022-02-03

    申请号:US17278473

    申请日:2019-06-24

    Abstract: A picture decoding method, performed by a decoding apparatus according to the present disclosure, comprises the steps of: when an intra-prediction mode of a chroma block is a cross-component linear model (CCLM) mode, deriving neighboring chroma reference samples with respect to the chroma block; deriving neighboring luma reference samples of a luma block corresponding to the chroma block and luma samples in the luma block; deriving down-sampled neighboring luma reference samples and downsampled luma samples by down sampling the neighboring luma reference samples and the luma samples, respectively; deriving a linear model parameter on the basis of the down-sampled neighboring luma reference samples and the neighboring chroma reference samples; generating prediction samples with respect to the chroma block on the basis of the linear model parameter and the down-sampled luma samples of the luma block; and reconstructing the chroma block on the basis of the prediction samples with respect to the chroma block.

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