Patent ID: 7881379

Claim:
A video decoding method for decoding encoded data obtained by subjecting a video image having a luminance and two color differences to predictive encoding, the video image having a luminance component and first and second color difference components, the method comprising: receiving encoded data obtained by encoding, for one or more to-be-decoded blocks, a plurality of combinations each comprising (A) a weighting factor every luminance and two color differences, (B) an offset every luminance and two color differences and (C) (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 (g) a flag indicating presence or non-presence of the weighting factor and the offset for the luminance component, and encoding, for a to-be-decoded block, (1) a quantized orthogonal transform coefficient of a prediction error signal relating to the luminance component and the two color differences difference components and (2) an index indicating a combination selected from the plurality of combinations, deriving, for the to-be-decoded block, a combination comprising the weighting factor factors and the offset offsets from the index and the plurality of combinations, 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 prediction image for the to-be-decoded block by multiplying the luminance component and color different components of a reference image respectively by the weighting factor factors and adding the offset offsets, respectively, to results of the multiplying, and generating a decoded image signal for the to-be-decoded block by calculating a sum of the prediction error signal and the prediction image.