US 12,143,574 B2
CCLM-based intra-prediction method and apparatus therefor
Jangwon Choi, Seoul (KR); Jin Heo, Seoul (KR); Sunmi Yoo, Seoul (KR); and Ling Li, Seoul (KR)
Assigned to LG Electronics Inc., Seoul (KR)
Filed by LG ELECTRONICS INC., Seoul (KR)
Filed on Sep. 21, 2023, as Appl. No. 18/371,319.
Application 18/371,319 is a continuation of application No. 17/834,532, filed on Jun. 7, 2022, granted, now 11,805,244.
Application 17/834,532 is a continuation of application No. 17/278,473, granted, now 11,394,961, previously published as PCT/KR2019/007575, filed on Jun. 24, 2019.
Claims priority of provisional application 62/741,531, filed on Oct. 4, 2018.
Prior Publication US 2024/0015282 A1, Jan. 11, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. H04N 19/00 (2014.01); H04N 19/105 (2014.01); H04N 19/132 (2014.01); H04N 19/159 (2014.01); H04N 19/176 (2014.01); H04N 19/186 (2014.01)
CPC H04N 19/105 (2014.11) [H04N 19/132 (2014.11); H04N 19/159 (2014.11); H04N 19/176 (2014.11); H04N 19/186 (2014.11)] 3 Claims
OG exemplary drawing
 
1. An image decoding method performed by a decoding apparatus, the method comprising:
obtaining residual information for a chroma block;
deriving neighboring chroma reference samples for the chroma block based on an intra prediction mode of the chroma block being a cross-component linear model (CCLM) mode;
deriving neighboring luma reference samples of a luma block corresponding to the chroma block and luma samples in the luma block;
deriving downsampled neighboring luma reference samples and downsampled luma samples by downsampling the neighboring luma reference samples and the luma samples;
deriving a linear model parameter based on the downsampled neighboring luma reference samples and the neighboring chroma reference samples;
generating prediction samples for the chroma block based on the linear model parameter and the downsampled luma samples of the luma block;
generating residual samples for the chroma block based on the residual information for the chroma block;
reconstructing the chroma block based on the prediction samples for the chroma block and the residual samples for the chroma block; and
performing a deblocking filtering on a reconstructed picture including the chroma block,
wherein the neighboring luma reference samples include top neighboring luma reference samples located above a top boundary of the luma block,
wherein the downsampled neighboring luma reference samples include a downsampled top neighboring luma reference sample, and
wherein based on the top boundary of the luma block being overlapped with a boundary of a coding tree unit (CTU), the downsampled top neighboring luma reference sample is derived based on an equation below,
pTopDsY[x]=(pY[2*x−1][−1]+2*pY[2*x][−1]+pY[2*x+1][−1]+2)>>2,
where pTopDsY[x] represents the downsampled top neighboring luma reference sample, x represents an x-axis direction position of the downsampled top neighboring luma reference sample, pY[2*x−1][−1], pY[2*x][−1] and pY[2*x+1][−1] represent sample values of the top neighboring luma reference samples, respectively, and a y-axis direction position of the top neighboring luma reference samples is −1.