IMAGE CODING APPARATUS AND METHOD THEREOF BASED ON A QUANTIZATION PARAMETER DERIVATION

    公开(公告)号:US20230007258A1

    公开(公告)日:2023-01-05

    申请号:US17944068

    申请日:2022-09-13

    Abstract: According to an embodiment of the present invention, a picture decoding method performed by a decoding apparatus is provided. The method comprises: decoding image information comprising information on a quantization parameter (QP), deriving an expected average luma value of a current block from neighboring available samples, deriving a quantization parameter offset (QP offset) for deriving a luma quantization parameter (luma QP) based on the expected average luma value and the information on the QP, deriving the luma QP based on the QP offset, performing an inverse quantization for a quantization group comprising the current block based on the derived luma QP, generating residual samples for the current block based on the inverse quantization, generating prediction samples for the current block based on the image information and generating reconstructed samples for the current block based on the residual samples for the current block and the prediction samples for the current block.

    IMAGE DECODING METHOD AND APPARATUS THEREFOR

    公开(公告)号:US20220408095A1

    公开(公告)日:2022-12-22

    申请号:US17894026

    申请日:2022-08-23

    Abstract: An image decoding method performed by a decoding apparatus, according to the present document, comprises the steps of: acquiring a transform skip available flag; acquiring a TSRC available flag on the basis of the transform skip available flag; acquiring prediction-related information regarding a current block; deriving a prediction sample of the current block on the basis of the prediction-related information; acquiring residual information of a residual coding syntax for the current block, derived on the basis of the TSRC available flag; deriving a residual sample of the current block on the basis of the residual information; and generating a reconstructed picture on the basis of the prediction sample and the residual sample.

    METHOD AND DEVICE FOR CODING TRANSFORM COEFFICIENT

    公开(公告)号:US20220385925A1

    公开(公告)日:2022-12-01

    申请号:US17882934

    申请日:2022-08-08

    Abstract: An image decoding method according to the present document comprises the steps of: receiving a bitstream including residual information; deriving a quantized transform coefficient for a current block on the basis of the residual information included in the bitstream; deriving a residual sample for the current block on the basis of the quantized transform coefficient; and generating a reconstructed picture on the basis of the residual sample for the current block, wherein the residual information may be derived via different syntax elements depending on whether a transform has been applied to the current block.

    IMAGE CODING METHOD BASED ON TRANSFORM, AND DEVICE THEREFOR

    公开(公告)号:US20220385912A1

    公开(公告)日:2022-12-01

    申请号:US17773234

    申请日:2020-11-02

    Abstract: An image decoding method according to the present document comprises the steps of: applying LFNST to transform coefficients to derive modified transform coefficients; deriving residual samples for a target block on the basis of an inverse primary transform for the modified transform coefficients; and generating a reconstructed picture on the basis of the residual samples, wherein the step of deriving the modified transform coefficients can comprise the steps of parsing an LFNST index on the basis of the current block tree type being a dual tree chroma, and deriving the modified transform coefficients on the basis of the LFNST index and an LFNST matrix.

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