Motion vector detecting circuit

Abstract

In an animation encoding process, a motion vector which can minimize an AC component included in a discrete cosine transform result is detected. For this purpose, a block X (i, j) to be processed is extracted from an input image X, and a prospective reference block Y,(i, J) is extracted from a reference image Y, wherein k is an integer depending upon the size of a motion vector search range, i=0, . . . , or 3, and j=0, . . . , or 63. From each pixel value in each sub block (including 8×8 pixels) of the block to be processed, an average value X,(i) of pixels in the sub block is subtracted, and from each pixel value in each sub block (including 8×8 pixels) of the prospective reference block, an average value Y,(i) of pixels in the sub block is subtracted. Then, an evaluation value S,for block matching is calculated. The prospective reference block having the minimum evaluation value is selected as a reference block among the plural prospective reference blocks, so as to obtain a motion vector V corresponding to the positional relationship between the block to be processed and the reference block.