| CPC H04N 19/186 (2014.11) [H04N 19/105 (2014.11); H04N 19/136 (2014.11); H04N 19/176 (2014.11)] | 16 Claims |
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1. A video decoding method performed by a decoding apparatus, the method comprising:
obtaining video information comprising prediction mode information for a current chroma block;
deriving a top cross-component linear model (CCLM) prediction mode as an intra prediction mode of the current chroma block based on the prediction mode information;
deriving a sample number of top neighboring chroma samples of the current chroma block based on a width of the current chroma block and a specific value;
deriving the top neighboring chroma samples of the sample number;
deriving down sampled top neighboring luma samples related with the top neighboring chroma samples and down sampled luma samples of a current luma block;
deriving CCLM parameters based on the top neighboring chroma samples and the down sampled top 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,
wherein the width of the current chroma block is N,
wherein based on 2N being less than or equal to twice the specific value, the sample number of the top neighboring chroma samples is derived as 2N, and
based on the 2N being greater than twice the specific value, the sample number of the top neighboring chroma samples is derived as 4.
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