Video encoding/ decoding method and apparatus

A video decoding apparatus of decoding encoded data generated by encoding a video image having luminance and two color differences to obtain the video image, comprising:

• a receiver configured to receive encoded data generated by encoding, for one or more to-be-decoded blocks, a plurality of combinations comprising (A) a weighting factor every luminance and two color differences and (B) an offset every luminance and two color differences, and encoding, for a to-be-decoded block, (1) a quantized orthogonal transform coefficient of a prediction error signal concerning luminance and two color differences and (2) a given number of index information elements indicating respectively one of the plurality of combinations;
• a deriving module configured to derive a given number of combinations comprising the weighting factor and the offset from the given number of index information elements and the plurality of combinations;
• a first generator configured to generate a prediction image for the to-be-decoded block by multiplying a given number of reference images respectively by the given number of weighting factors corresponding to the reference images and adding the given number of offsets;
• 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.