Color registration system for a printing press

摘要

A control system is disclosed for controlling misregistration between the colors of an image printed on a web. The system includes an imaging device such as a camera or group of cameras, a processor, and image conversion circuits coupled to the processor. The system detects print color misregistration based upon the signals produced by the imaging device as a result of scanning the printed image. The conversion circuits convert the signals to signals usable by the processor to determine the color densities of the various colors within the image. These on-press color densities are compared with reference color densities stored in a memory of the processor, wherein the reference color densities may be generated from a source such as the printing plates used to print the image for which misregistration is being monitored. Based upon the phase correlation of the on-press images with the reference images, a processor operates to produce registration offset values between the printed colors and controls a print controller which adjusts the print units such that the colors of the printed image are placed into registration.