Patent ID: 8098898

Claim:
A motion detection device for performing a motion detection for a current frame image by referring to a reference frame image, said motion detection device comprising: a current image memory for storing at least a first one of a plurality of current macroblock images, which together form the current frame image; a reference image memory for storing, as a reference image, a subset of a plurality of reference macroblock images, which together form the reference frame image, a reference image memory control section for storing the reference image in the reference image memory or outputting those of the reference images that are present within a motion estimation range from the reference image memory; and a motion detection section for performing a motion estimation for those of the reference images that are present within the motion estimation range and detecting a motion vector for the first current macroblock image, wherein when the motion detection section detects a motion vector for the first current macroblock image, the reference image memory control section determines an estimation starting point for the first current macroblock image to be a point reached by moving from one point within the first current macroblock image by a surrounding motion vector which is a motion vector detected for a current macroblock image present around the first current macroblock image, and determines the motion estimation range so that the current macroblock image in which the estimation starting point is present is located at a center of the motion estimation range.