An automation visual inspection system for color overprint deviation

Now, registration precision is usually adjusted by handwork that is an undeveloped method for multi-color printing machines in china. To solving this problem, a machine vision system was designed and developed for automatically detecting the overprint deviation. The system consisted of a video camera and a PC computer with image processing hardware and software. The image of the measuring marker of plate captured by CCD, recognized and analyzed the registration marker by the statistic character of hue in HSI space, and segmented the color image by means of threshold, that edge pixels of color marker are extracted, and their structural lines are approximated by least squares approximations, final, the deviation from each other is obtained. Experimental results show that the system can fast enough measure the exact overprint deviation in color printing and have used to examine the overprint precision in Beiren Printing Machinery Co., Ltd.