Measurement element for multiple colour offset printing - determines match difference between two partial images independently of quality of image signal

摘要

A measurement element for determining a match difference between two partial images in mutliple colour offset printing consists of a measurement marker (1,2) printed in both images. The mutual displacement of the markers representing the match difference is detected by a linewise photoelectric scan. Each marker is a continuous sequence of alternately printed and blank parallel strips (3.1-3.n) of unequal width. The match difference is determined in the direction of the strip sequence from the maximum of a correlation function.