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US 11,902,527 B2Granted
Video or image coding based on mapping of luma samples and scaling of chroma samples
AssigneeLG Electronics Inc.
InventorsJie Zhao, Seunghwan Kim
Life of this patent
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Abstract
According to the disclosure of the present document, it is possible for various LMCS application cases to apply an LMCS procedure to a block having a dual tree structure. In addition, the coding predormance of the block can be improved. According to the disclosure of the present document, resources required for the LMCS procedure can be reduced. Therefore, the complexity of the LMCS can be reduced and the video/image coding efficiency can be increased.
Claims11
An image decoding method performed by a decoding apparatus, the method comprising:
- obtaining image information including prediction information, residual information and information on luma mapping with chroma scaling (LMCS) data from a bitstream;
- generating predicted luma samples based on the prediction information;
- deriving LMCS codewords based on the information on the LMCS data;
- generating mapped predicted luma samples based on the predicted luma samples and the LMCS codewords;
- deriving residual samples based on the residual information, wherein the residual samples includes residual luma samples and residual chroma samples;
- generating reconstructed luma samples based on the mapped predicted luma samples and the residual luma samples;
- and
- generating modified reconstructed luma samples based on the reconstructed luma samples and the LMCS codewords,
- wherein the image information includes LMCS adaptation parameter sets (APSs),
- wherein an LMCS APS includes type information indicating that the LMCS APS is an APS including an LMCS data field,
- wherein the LMCS APS includes the LMCS data field based on the type information,
- wherein the LMCS data field includes the information on the LMCS data,
- wherein a maximum number of the LMCS APS is a specific value,
- wherein the specific value is 4,
- wherein the method further comprises:
- deriving a chroma residual scaling factor based on a piece wise index;
- and
- generating scaled residual chroma samples based on the residual chroma samples and the chroma residual scaling factor,
- wherein the piecewise index is identified based on the information on the LMCS data.
16 more elements
An image encoding method performed by an encoding apparatus, the method comprising:
- generating predicted samples for a current block in a current picture, wherein the predicted samples include predicted luma samples and predicted chroma samples;
- deriving luma mapping with chroma scaling (LMCS) codewords and bins for luma mapping;
- generating mapped predicted luma samples based on the LMCS codewords and the bins for the luma mapping;
- generating reconstructed luma samples based on the mapped predicted luma samples;
- generating modified reconstructed luma samples based on the reconstructed luma samples, the LMCS codewords, and the bins for the luma mapping;
- deriving information on LMCS data based on the LMCS codewords and the bins for the luma mapping;
- generating residual luma samples based on the mapped predicted luma samples;
- generating residual information based on the residual luma samples;
- generating residual chroma samples based on the predicted chroma samples;
- and
- encoding image information including the residual information and the information on the LMCS data,
- wherein the image information includes LMCS adaptation parameter sets (APSs),
- wherein an LMCS APS includes type information indicating that the LMCA APS is an AP including an LMCS data field,
- wherein the LMCS APS includes the LMCS data field based on the type information;
- wherein the LMCS data field includes the information on the LMCS data,
- wherein a maximum number of the LMCS APS is a specific value,
- wherein the specific value is 4,
- wherein the method further comprises:
- deriving a chroma residual scaling factor based on a piecewise index;
- and
- generating scaled residual chroma samples based on the residual chroma samples and the chroma residual scaling factor,
- wherein the piecewise index is identified based on the information on the LMCS data.
19 more elements
A non-transitory computer-readable storage medium storing a bitstream generated by a method, the method comprising:
- generating predicted samples for a current block in a current picture, wherein the predicted samples include predicted luma samples and predicted chroma samples;
- deriving luma mapping with chroma scaling (LMCS) codewords and bins for luma mapping;
- generating mapped predicted luma samples based on the LMCS codewords and the bins for the luma mapping;
- generating reconstructed luma samples based on the mapped predicted luma samples;
- generating modified reconstructed luma samples based on the reconstructed luma samples, the LMCS codewords, and the bins for the luma mapping;
- deriving information on LMCS data based on the LMCS codewords and the bins for the luma mapping;
- generating residual luma samples based on the mapped predicted luma samples;
- generating residual information based on the residual luma samples;
- generating residual chroma samples based on the predicted chroma samples;
- and
- encoding image information including the residual information and the information on the LMCS data,
- wherein the image information includes LMCS adaptation parameter sets (APSs),
- wherein an LMCS APS includes type information indicating that the LMCA APS is an AP including an LMCS data field,
- wherein the LMCS APS includes the LMCS data field based on the type information;
- wherein the LMCS data field includes the information on the LMCS data,
- wherein a maximum number of the LMCS APS is a specific value,
- wherein the specific value is 4,
- wherein the method further comprises:
- deriving a chroma residual scaling factor based on a piecewise index;
- and
- generating scaled residual chroma samples based on the residual chroma samples and the chroma residual scaling factor,
- wherein the piecewise index is identified based on the information on the LMCS data.
19 more elements
Dependencies are inferred from the claim text.