ADAPTIVE DIFFERENCE COMPUTING ELEMENT AND MOTION ESTIMATION APPARATUS DYNAMICALLY ADAPTING TO INPUT DATA

An adaptive difference computing element which consumes less power without any decrease in calculation accuracy includes: a first circuit receiving first and second data with the same bit lengths and each having bits at one and the other ends, determining if a prescribed relation is obtained between a bit string from each bit to the bit at one end of the first data and that of the second data for each bit of the first data and corresponding each bit of the second data, and replacing the each bit of the first data and the corresponding each bit of the second data with same predetermined bit values if the prescribed relation is obtained, and otherwise directly outputting the first and second data; and a subtracter having inputs connected to receive the first and second data from the first circuit, respectively.