1. An image processing apparatus for compressing an input image using a motion vector, the image processing apparatus comprising: means for storing position information of each pixel of a first frame at an address corresponding to a feature of the pixel, the first frame being earlier in time than a second frame; means for detecting the position information stored at an address corresponding to a feature of a target pixel of the second frame; means for determining differences between a pixel value of the target pixel and pixel values of candidate pixels of the first frame which are identified with the detected position information; and means for detecting a motion vector of the target pixel from the position of the target pixel and the position of one of the candidate pixels when a minimum of the differences is determined.