Patent ID: 7885328

Claim:
A video decoding method for decoding encoded data obtained by subjecting a video image to prediction encoding, the video image having a luminance component and first and second color difference components, the method comprising: receiving an input of encoded data obtained by encoding, for one or more to-be-decoded blocks, a combination selected from a plurality of combinations, each combination comprising (1) (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, and (2) a flag indicating presence or non-presence of the weighting factors and the offsets concerning the color difference components, and encoding, for the to-be-decoded block, (A) a quantized orthogonal transform coefficient of a prediction error signal concerning the luminance and color difference components and (B) index indicating (a) one combination of the plurality of combinations and (b) a reference image; deriving the weighting factors and the offsets from the plurality of combinations and the index; generating a prediction image by multiplying the luminance and the first and second color difference components of the reference image by the weighting factors, respectively, and adding the offsets, respectively, to the results of the multiplying; generating a prediction error signal by subjecting the quantized orthogonal transform coefficient to inverse quantization and inverse orthogonal transform; and generating a decoded image signal by calculating a sum of the prediction error signal and the prediction image, wherein the weighting factors and the offsets which are derived from two of the indexes corresponding to the different reference images respectively are identical.