Patent ID: 7542510

Claim:
An image decoding method for generating a predictive pixel value of a current picture to be decoded, using pixel values of two reference pictures, and decoding the current picture using the predictive pixel value, the method comprising: a first parameter calculation step of calculating, using a first parameter calculation unit, a first parameter corresponding to a temporal distance between the current picture and a first reference picture; a second parameter calculation step of calculating, using a second parameter calculation unit, a second parameter corresponding to a temporal distance between the first reference picture and a second reference picture; a judgment step of judging, using a judgment unit, whether or not a value of a third parameter calculated based on the first and the second parameters is included in a predetermined range; a predictive pixel value generation step of (i) generating, using a predictive pixel value generation unit, a predictive pixel value of the current picture by scaling a pixel value of the first reference picture and a pixel value of the second reference picture using a weighting coefficient calculated by the first parameter and the second parameter, in a case where it is judged, in said judgment step, that the value of the third parameter is included in the predetermined range, and (ii) generating, using the predictive pixel value generation unit, a predictive pixel value of the current picture by scaling a pixel value of the first reference picture and a pixel value of the second reference picture using a weighting coefficient of a predetermined value, in a case where it is judged, in said judgment step, that the value of the third parameter is not included in the predetermined range; and a decoding step of decoding, using a decoding unit, the current picture using the predictive pixel value calculated in said predictive pixel value generation step.