In relation to search positions within a search range determined with a reference image block located in the same position as a standard block of interest, correlation computation is performed by parallel processing under a pipeline method through use of a plurality of correlation computing units. A correlation extreme value is searched while the center position is sequentially moved on the basis of a predetermined search position setting standard according to the result of correlation computation. Further, sub-sampled image data for a plurality of channels corresponding to the search positions are retained in system memory for a plurality of channels, and correlation computation is performed in connection with search positions through parallel processing under a pipeline method through use of the plurality of correlation computing units.