Patent ID: 8023753

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 reference pictures; information that indicates a maximum reference index value; sets of weighting coefficients used for generating a predictive image; 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; specifying a set of weighting coefficients that corresponds to the reference index from among the sets of weighting coefficients; generating the predictive image by performing linear prediction, using the specified set of weighting coefficients, 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, information of said sets of weighting coefficients used for generating a predictive image are placed in a slice header of the coded image signal, and wherein, in the case that the current block is a block included in a P picture and the current block is decoded by designating one reference picture which is referred to, each of said sets of weighting coefficients comprises a first part w 1 and a second part c 1 , the first part w 1 being used for scaling pixel values of the reference block and the second part c 1 being used for increasing each of the scaled pixel values by a value of c 1 .