Patent ID: 7876817

Claim:
A video decoding method performed by a video decoder for decoding encoded data obtained by subjecting a video image to motion compensation prediction encoding, the video image having a luminance component and first and second color difference components, the video decoding method comprising: receiving as an input of encoded data obtained by encoding for a to-be- decoded block (1) a quantized orthogonal transformation coefficient of a prediction error signal concerning the luminance component and the first and second color difference components, (2) information of a motion vector and (3) an index indicating a combination comprising (A) a first weighting factor for the luminance component, (B) a second weighting factor for the first color difference component, (C) a third weighting factor for the second color difference component, (D) a first offset for the luminance component, (E) a second offset for the first color difference component, and (F) a third offset for the second color difference component; deriving the weighting factors and the offsets from the index for the to-be-decoded block; generating the prediction error signal for the to-be-decoded block by subjecting the quantized orthogonal transform coefficient to inverse quantization and inverse orthogonal transform; generating a motion compensation prediction image for the to-be-decoded block by multiplying the luminance component and the first and second color difference components of a reference image by the weighting factors, respectively, and adding the offsets, respectively, to results of the multiplying, based on the motion vector for the to-be-decoded block; and generating, by the video decoder, a decoded image signal for the to-be-decoded block by calculating a sum of the prediction error signal and the motion compensation prediction image.