US 11,902,527 B2
Video or image coding based on mapping of luma samples and scaling of chroma samples
Jie Zhao, Seoul (KR); and Seunghwan Kim, Seoul (KR)
Assigned to LG ELECTRONICS INC., Seoul (KR)
Filed by LG ELECTRONICS INC., Seoul (KR)
Filed on Sep. 12, 2022, as Appl. No. 17/942,691.
Application 17/942,691 is a continuation of application No. 17/556,780, filed on Dec. 20, 2021, granted, now 11,477,456.
Application 17/556,780 is a continuation of application No. PCT/KR2020/008046, filed on Jun. 22, 2020.
Claims priority of provisional application 62/864,478, filed on Jun. 20, 2019.
Prior Publication US 2023/0024786 A1, Jan. 26, 2023
Int. Cl. H04N 19/132 (2014.01); H04N 19/176 (2014.01); H04N 19/186 (2014.01); H04N 19/70 (2014.01); H04N 19/96 (2014.01)
CPC H04N 19/132 (2014.11) [H04N 19/176 (2014.11); H04N 19/186 (2014.11); H04N 19/70 (2014.11); H04N 19/96 (2014.11)] 11 Claims
OG exemplary drawing
 
1. 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.