Transform coefficient coding method and device therefor

    公开(公告)号:US11240508B2

    公开(公告)日:2022-02-01

    申请号:US17217526

    申请日:2021-03-30

    Abstract: An image decoding method performed by a decoding device according to the present document comprises a step of receiving a bitstream containing residual information, and a step of deriving a quantized transform coefficient for a current block on the basis of the residual information contained in the bitstream, wherein the residual information includes a context syntax element coded on the basis of the context, and if the size of a transformation block is changed as much as a sub-block region having a predetermined size and the current block is the last sub-block in the sub-block region and the last quantized transform coefficient is in the current block, then the step of deriving a quantized transform coefficient includes context-based decoding of the context syntax element on the basis of a predetermined maximum value for the context syntax element, wherein the maximum value is determined on the basis of the size of the sub-block region.

    METHOD AND DEVICE FOR PROCESSING VIDEO SIGNAL FOR INTRA PREDICTION

    公开(公告)号:US20210400263A1

    公开(公告)日:2021-12-23

    申请号:US17406528

    申请日:2021-08-19

    Abstract: Embodiments of the present specification provide a method and a device for processing a video signal for intra prediction. A method for decoding a video signal according an embodiment of the present disclosure includes: obtaining intra prediction information of a current block to which the intra prediction is applied, in which the intra prediction information includes a first flag indicating a predetermined first mode; determining an intra prediction mode of the current block based on the intra prediction information, wherein when the first flag corresponds to a first value, the first mode is determined as the intra prediction mode and when the first flag corresponds to a second value, one of a plurality of candidate modes is determined as the intra prediction mode; and generating a prediction sample of the current block based on the intra prediction mode and a reference sample in a current picture. A separate flag indicating whether to use a primarily used specific mode is used to reduce a data amount for transmission of the intra prediction mode and a processing time of information of the intra prediction.

    Method and apparatus for decoding image by using transform according to block size in image coding system

    公开(公告)号:US11206403B2

    公开(公告)日:2021-12-21

    申请号:US16853484

    申请日:2020-04-20

    Abstract: A method for decoding an image by a decoding apparatus according to the present invention comprises the steps of: deriving predicted samples by performing prediction on a current block; determining whether the current block is to be divided, on the basis of a size and a maximum transform size of the current block; when the current block is determined to be divided, dividing the current block into transform blocks; deriving transform coefficients of the transform blocks; deriving residual samples by performing an inverse transform procedure for the transform coefficients; and generating a reconstructed picture on the basis of the residual samples and the predicted samples, wherein, when the size of the current block is larger than the maximum transform size, the current block is determined to be divided.

    Method for decoding image on basis of CCLM prediction in image coding system, and device therefor

    公开(公告)号:US11012699B2

    公开(公告)日:2021-05-18

    申请号:US16892095

    申请日:2020-06-03

    Abstract: A video decoding method performed by a decoding apparatus according to the present disclosure includes deriving one of a plurality of cross-component linear model (CCLM) prediction mode as a CCLM prediction mode of the current chroma block, deriving a sample number of neighboring chroma samples of the current chroma block based on the CCLM prediction mode of the current chroma block, a size of the current chroma block, and a specific value; deriving the neighboring chroma samples of the sample number, calculating CCLM parameters based on the neighboring chroma samples and the down sampled neighboring luma samples, deriving prediction samples for the current chroma block based on the CCLM parameters and the down sampled luma samples and generating reconstructed samples for the current chroma block based on the prediction samples, wherein the specific value is derived as 2.

    Residual coding method and device for same

    公开(公告)号:US10992935B2

    公开(公告)日:2021-04-27

    申请号:US16856898

    申请日:2020-04-23

    Abstract: A method for decoding a picture performed by a decoding apparatus according to the present disclosure includes receiving a bitstream including residual information, deriving a quantized transform coefficient for a current block based on the residual information included in the bitstream, deriving a transform coefficient from the quantized transform coefficient based on a dequantization process, deriving a residual sample for the current block by applying an inverse transform to the derived transform coefficient, and generating a reconstructed picture based on the residual sample for the current block.

    METHOD FOR DECODING IMAGE ON BASIS OF CCLM PREDICTION IN IMAGE CODING SYSTEM, AND DEVICE THEREFOR

    公开(公告)号:US20200296391A1

    公开(公告)日:2020-09-17

    申请号:US16892095

    申请日:2020-06-03

    Abstract: A video decoding method performed by a decoding apparatus according to the present disclosure includes deriving one of a plurality of cross-component linear model (CCLM) prediction mode as a CCLM prediction mode of the current chroma block, deriving a sample number of neighboring chroma samples of the current chroma block based on the CCLM prediction mode of the current chroma block, a size of the current chroma block, and a specific value; deriving the neighboring chroma samples of the sample number, calculating CCLM parameters based on the neighboring chroma samples and the down sampled neighboring luma samples, deriving prediction samples for the current chroma block based on the CCLM parameters and the down sampled luma samples and generating reconstructed samples for the current chroma block based on the prediction samples, wherein the specific value is derived as 2.

    Intra prediction method and device in image coding system

    公开(公告)号:US10721492B2

    公开(公告)日:2020-07-21

    申请号:US15762946

    申请日:2016-09-08

    Abstract: An intra prediction method includes: receiving intra prediction mode information through a bitstream; deriving an intra prediction mode of a current block as a first intra directional mode on the basis of the intra prediction mode information; deriving first neighboring samples of the current block; deriving a reference sample adjacent to a target sample in the current block on the basis of a prediction direction of the first intra directional mode; deriving second neighboring samples of a neighboring block to which the reference sample belongs; determining a modified prediction direction on the basis of a comparison between the reference sample and at least one of the second neighboring samples; and deriving a prediction value for the target sample on the basis of the modified prediction direction and the first neighboring samples.

    Image encoding/decoding method and apparatus therefor

    公开(公告)号:US10681354B2

    公开(公告)日:2020-06-09

    申请号:US16466579

    申请日:2016-12-05

    Inventor: Jin Heo

    Abstract: A method for encoding/decoding an image and a device therefor are disclosed. Specifically, the method for decoding the image by the decoding device, the method includes deriving an intra prediction mode of a current block, constructing reference samples with samples adjacent to an top of the current block and samples adjacent to a left of the current block, and generating a prediction sample, when the intra prediction mode is a vertical/horizontal strong mode, using a reference sample having the same x-coordinate as the sample, a reference sample having the same y-coordinate as the sample, a reference sample adjacent to a bottom-left of the current block, and a reference sample adjacent to an top-right of the current block among the reference samples for each sample in the current block, wherein a weighting value w1 applied to the reference sample having the same y-coordinate as the sample and the reference sample adjacent to the top-right of the current block and a weighting value w2 applied to the reference sample having the same x-coordinate as the sample and the reference sample adjacent to the bottom-left of the current block are set to be different from each other.

    Image decoding method and apparatus relying on intra prediction in image coding system

    公开(公告)号:US10638157B2

    公开(公告)日:2020-04-28

    申请号:US16340617

    申请日:2017-08-30

    Inventor: Jin Heo

    Abstract: An image decoding method performed by a decoding apparatus according to the present invention comprises: a step of deriving an intra prediction mode for a current block; a step of deriving upper neighboring samples of a plurality of rows for the current block, and left neighboring samples of a plurality of columns; a step of deriving one row of upper reference samples on the basis of the upper neighboring samples; a step of deriving one column of left reference samples on the basis of the left neighboring samples; and a step of generating a prediction sample for the current block by using at least one of the upper reference samples and the left reference samples in accordance with the intra prediction mode.

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