A compact, inexpensive, real-time device for computing dense stereo range and motion field images, which are fundamental measurements supporting a wide range of computer vision systems that interact with the real world, where objects move through three-dimensional space includes a novel algorithm for image-to-image comparison that requires less storage and fewer operations than other algorithms. A combination of standard, low-cost and low-power components are programmed to perform algorithm and performs realtime stereo and motion analysis on passive video images, including image capture, digitization, stereo and/or motion processing, and transmission of results.