Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
From observing equipment that optically recognizes components placement at my workplace; I would guess you need at least a couple of video cameras, high contrast video gain or processing circuit and mapping patterns of light/dark at every area of interest to be scanned.
Somehow software should have a reference treshold/boundaries of the mapping to decide what is acceptable and what is not.