The layout of the prototype is shown in Fig. 5. The system is made up of a progressive scan digital CCD camera, a spotlight source, a conveyor belt with a framework to sustain the object to be inspected, two1 high reflective surfaces (plane mirrors) and a desktop PC for image acquisition and processing. The light source is a Spotlight MiniProfile lamp which projects a circular light beam, that can be shaped by means of four adjustable shutters. The light hits the high reflective surfaces which act as mirrors. The object to be investigated is placed on a special framework which guarantees its correct alignment with respect to the lighting system and to the camera. The framework slides on a conveyor belt at a speed of 21 mm/s. The camera is a gray scale Basler A302b, with a resolution of View the MathML source and a maximum frame rate of 60 Hz. The camera is connected to the PC by means of a Matrox Meteor-II digital frame grabber, which holds a preprocessor for fast and accurate image processing. The whole system, except from the computer unit, is located inside a sort of black box, to avoid external light sources interfere with the vision system (see Fig. 6).