| CPC H04N 19/186 (2014.11) [H04N 19/12 (2014.11); H04N 19/124 (2014.11); H04N 19/132 (2014.11); H04N 19/176 (2014.11); H04N 19/18 (2014.11); H04N 19/463 (2014.11)] | 15 Claims |
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1. An image decoding method performed by an image decoding apparatus, the method comprising:
deriving a transform coefficient for each of the luma component block, the chroma Cb component block, and the chroma Cr component block based on a quantization parameter for each of a luma component block, a chroma Cb component block, and a chroma Cr component block;
deriving a residual sample for each of the luma component block, the chroma Cb component block, and the chroma Cr component block based on the transform coefficient;
modifying a value of the residual sample for each of the luma component block, the chroma Cb component block, and the chroma Cr component block based on color space transform information; and
reconstructing the luma component block, the chroma Cb component block, and the chroma Cr component block based on the residual sample for each of the luma component block, the chroma Cb component block, and the chroma Cr component block;
wherein the quantization parameter is derived based on a quantization parameter offset,
wherein the value of each residual sample is modified based on a half value of the residual sample for the chroma Cb component block.
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