disclosed is a method for interpolating chrominance signals in a video encoder and a decoder . the method includes the steps of accessing a memory unit to load an integer pixel value with regard to a plurality of motion compensation blocks , searching for a location of a motion vector s to perform sub - pixel interpolation of chrominance signals regarding the blocks and performing ¼ sub - pixel interpolation by row - based and column - based shifting when the motion vector indicates a ¼ location pixel with regard to the blocks . also disclosed is an apparatus for performing the interpolating method described and a computer program product which when loaded into a computer system performs the interpolating method described .