Abstract

Using marks of known dimensions and size, and spacing, a zoom lens may be calibrated in either or both the X and Y spatial directions. A system comprising an image capture device, positioning means, position encoder means, operator interface, and processing unit permits this method to be advantageously applied to a wide variety of web inspection/control functions, including but not limited to initial web registration, multiple color ink registration, lateral web positioning, repeat length calculations, image capture synchronization, thermal/mechanical differential compensation, and accurate registration of objects within an image to other objects within an image or to a mechanical reference on a machine. Since the Zoom Calibration method permits a system to be constructed with both wide/variable field of view and accurate distance measurement positioning and calibration, all of the web inspection/control functions traditionally used in the web printing industry may be implemented with a single inspection/control system using a multitasking approach with the same inspection/control hardware. This permits rapid implementation of old and new web inspection/control functions at a greatly reduced cost as compared to traditional fixed lens systems, as well as permitting a degree of automation, remote access, diagnostic control, quality assurance, and product quality control heretofore not possible with conventional web inspection/control systems.