Research on registration algorithm of plane digital die cutting based on visual image

Digitalization is an important trend in the development of printing industry. Digital die cutting is the key post press process of digital printing, and its registration accuracy directly affects the product quality. Based on the analysis of the positioning principle of die-cutting machine, this paper presents a registration algorithm for detecting the paper deviation and skew of die-cutting machine by using visual sensor. The detected image information is gray and binarized. Through the binary image and the equivalent relationship between the pixel and the actual size,the corresponding offset and skew angle are calculated. Taking the coordinates of the plane die-cutting machine as WCS coordinate and the image coordinates as LCS coordinates, the conversion matrix between LCS coordinates and WCs coordinates is established. Through the conversion matrix, the anchor coordinates on the knife line file can be converted into the LCS coordinates of the actual paper feeding machine coordinate system considering the paper feeding offset and offset angle, ensure the registration accuracy.