Scalable video encoding method and decoding method, apparatuses therefor, programs therefor, and storage media which store the programs

Abstract

A scalable video encoding method of performing encoding by predicting an upper-layer signal having a relatively high spatial resolution by means of interpolation using an immediately-lower-layer signal having a relatively low spatial resolution. The method computes a first weighting coefficient for each image area of a predetermined unit size in a search for estimating a motion between an encoding target image area in an upper layer and a reference image area, where the first weighting coefficient is computed based on a brightness variation between an image area, which belongs to an immediately-lower layer and has the same spatial position as the encoding target image area, and the reference image area; and performs a motion estimation using a signal which is obtained by correcting a decoded signal of the reference image area by the first weighting coefficient and functions as an estimated signal in the motion estimation, so as to compute a motion vector. Then the method computes a second weighting coefficient based on a brightness variation between a reference image area indicated by the motion vector and the image area which belongs to the immediately-lower layer and has the same spatial position as the encoding target image area; and determines a signal, which is obtained by correcting a decoded signal of the reference image area by using the second weighting coefficient, to be a compensated signal in motion compensation, which functions as a predicted signal of the encoding target image area.