Patent ID: 7848420

Claim:
A video encoding method for subjecting an input video image to predictive encoding, the input video image having a luminance component and first and second color difference components, the method comprising: determining, for a to-be-encoded block of the input video image, a reference image and 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 an index indicating the determined combination, wherein two values of the index corresponding to different reference images each indicate an identical combination of the weighting factor and the offset, and a value obtained by subjecting one of the two values of the indexes to arithmetic shift right by one bit is identical to a value obtained by subjecting the other of the two values of the indexes to arithmetic shift right by one bit; generating a prediction image for the to-be-encoded 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; generating a prediction error signal for the to-be-encoded block by calculating an error between the input video image and the prediction image; generating a quantized orthogonal transform coefficient for the to-be-encoded block by subjecting the prediction error signal to orthogonal transform and quantization; and encoding (1) the quantized orthogonal transform coefficient and (2) the index.