Detection and Control Algorithm of Multi-Color Printing Registration Based on Computer Vision

In color printing the image of each color plate should be registered strictly, so the registration marks are needed. But when using the computer vision system to monitor the registration state automatically, the traditional cross marks are not a good choice because the several colors will overprint and form new color. A method to detect and control registration state is proposed in the paper. The main points of the method are followings: first, instead of the traditional cross mark, the position fixed single color round registration marks are used; second, the position of each mark´s center is detected by gravity centre algorithm. The accurate of this method is also discussed in the paper.