TRIPOD is free and open source software for rapidly developing computer vision applications. With such software, robot vision systems can be developed, tested and validated. This paper presents a step-by-step tutorial where live video is thresheld to display the corresponding binary image. This simple exercise serves to illustrate the realization of a robot vision system. A LEGO Mindstorms Vision Command module, which is a Logitech USB camera, is used. Platform development is in ANSI C/C$++$ on a Windows PC without low-level Windows programming.