Patent ID: 7308145

Claim:
A picture decoding method comprising: decoding a coded image signal to obtain: a reference index that identifies a reference picture for a current block to be decoded; commands that indicate correspondence between reference indices and picture numbers indicating a decoding order of coded pictures; information that indicates a maximum reference index value; and a prediction error; designating, based on the commands and the reference index, a reference picture which is referred to when the current block is decoded through motion compensation; generating a weighting coefficient based on display order information that indicates a display order of pictures; generating a predictive image by performing linear prediction, using the weighting coefficient, on pixel values of a reference block obtained from the reference picture designated in said designating; and generating a reconstructed image from the predictive image and the prediction error, wherein the reference index includes a first reference index that identifies a first reference picture and a second reference index that identifies a second reference picture, and in said generating of the predictive image, the predictive image is generated by performing linear prediction on the pixel values of the reference block using a pre-defined weighting coefficient when the first reference picture identified by the first reference index and the second reference picture identified by the second reference index have identical display order information.