Patent ID: 7843996

Claim:
A video decoding apparatus of decoding encoded data obtained by subjecting a video image to predictive encoding, the video image having a luminance component and first and second color difference components, the apparatus comprising: a receiver configured to receive encoded data obtained by encoding, for a to-be-decoded block, (1) a quantized orthogonal transform coefficient of a prediction error signal concerning the luminance component and the first and second color difference components and (2) an index indicating (a) a reference image and (b) 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; a deriving module configured to derive the weighting factors and the offsets from the index; a first generator configured to generate a prediction image for the to-be-decoded block by multiplying the luminance component and the first and second color difference components of the reference image by the weighting factors, respectively, and adding the offsets, respectively, to results of the multiplying; a second generator configured to generate the prediction error signal for the to-be-decoded block by subjecting the quantized orthogonal transform coefficient to inverse quantization and inverse orthogonal transform; and a third generator configured to generate a decoded image signal for the to-be-decoded block by calculating a sum of the prediction error signal and the prediction image, wherein two values of indexes corresponding to different reference images indicate an identical combination of the weighting factor and the offset, and a value obtained by subjecting one of the two values to arithmetic shift right by one bit is identical to a value obtained by subjecting the other of the two values to arithmetic shift right by one bit.