Patent ID: 7852932

Claim:
A prediction image generation method for generating a prediction image from 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 a to-be-decoded block, an index indicating 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; selecting either a frame unit or a field unit as a decoding unit; deriving, for the to-be-decoded block, the weighting factors and the offsets from the index; and generating a prediction image by multiplying the luminance component and the first and second color difference components of a reference image by the weighting factors, respectively, and adding the offsets, respectively, to results of the multiplying; wherein the weighting factors and the offsets derived from the index when the decoding unit is the field unit is identical to the weighting factors and the offsets derived from the index when the decoding unit is the frame unit, which has a value obtained by subjecting a value of the index when the decoding unit is the field unit to a right arithmetic shift by one bit.