Abstract: An image processing apparatus, wherein image data is stored in a current block memory and image data of a search range of a reference picture is stored in a search window memory. Using a gray code, the register file of the search window memory is read, candidate blocks are successively extracted, and the image data is successively input to processor elements. The data stored in the current block memory is input to a register and input through a barrel shifter to the processor elements. The processor elements find the differences of the current block and candidate blocks, find the cumulative values, compare the cumulative values of differences at a comparison unit, extract the candidate block giving the smallest value, and detect the motion vector based on the candidate block.