Patent ID: 7224732

Claim:
A motion vector conversion method for an image information conversion method wherein a bit stream representative of interlaced scanned image compression information of MPEG2 is inputted and a bit stream representative of progressively scanned image compression information of MPEG4 is outputted, comprising the steps of: successively accepting 16×16 motion vectors of MPEG2 of the inputted bit stream representative of image compression information of MPEG2; and successively producing 8×8 motion vectors of MPEG4 and 16×16 motion vectors of MPEG4 based on the 16×16 motion vectors of MPEG2 such that every other one of I frames and P frames of the bit stream of MPEG2 is dropped to produce a bit stream of MPEG4 of a reduced frame rate and a low bit rate; the successively producing step including a step of utilizing, as a parameter for discrimination of the coding efficiency of a motion vector of MPEG4 converted from an intra-frame of MPEG2, motion vector information of each of macro blocks and between blocks of the inputted bit stream representative of image compression information of MPEG2 converted immediately preceding to the intra-frame to compare the motion vector information with a prediction value of the 0 motion vector to select one of the motion vectors which exhibit a comparatively small prediction residual as a motion vector having a comparatively high coding efficiency.