Abstract :
Over the past 20 years machine vision has grown from an infancy of exciting but mostly unrealisable prospects into a mature field in which sophisticated real-time systems can be installed economically in agricultural, industrial, medical, surveillance, transport and many other applications. In these areas it is commonly applied to active control, e.g. of guided vehicles and robots, but there are many other situations where it is used more passively to check for intruders, to keep a watch on the flow of people (e.g. on streets or on the underground) or to monitor industrial plant. In this last category falls the subject of automated visual inspection. Automated visual inspection is largely concerned with the maintenance of standards, and particularly to ensure that precision parts are made with the correct dimensions, the right number of holes in the right places. and so on. It is also concerned with checking that more complex parts have been assembled correctly and with the right tolerances, and in these respects it merges imperceptibly with automatic or robot assembly
