MOTION DETECTION DEVICE, MOS (METAL-OXIDE SEMICONDUCTOR) INTEGRATED CIRCUIT, AND VIDEO SYSTEM

A motion detection device includes a current image memory, a reference image memory, a reference image memory control section, and a motion detection section. When the motion detection section detects a motion vector for a first current macroblock image, the reference image memory control section determines a motion estimation range by using a surrounding motion vector being a motion vector detected for a current macroblock image present around the first current macroblock.