Automated real-time visual inspection system for high-resolution superimposed printings

This paper describes an automatic real-time inspection system of printed products. This system has been applied to the inspection of objects having superimposed printings with different reference systems at high resolution, that is, there are not two identical products. The automation of this process is particularly critical and its solution is highly complex. The techniques employed are based on a combination of various disciplines, allowing a compromise between resolution and processing speed. In this way, disciplines such as morphological processing, subpixel accuracy, scheduling techniques, parallel processing, etc. are incorporated. (C) 1998 Elsevier Science B.V. All rights reserved.