PROCESS AND APPARATUS FOR THE EVALUATION OF THE PRINTING QUALITY OF A PRINTED PRODUCT PRODUCED BY AN OFFSET PRINTING MACHINE

摘要

Printed products and their respective corresponding printing plates are divided into a plurality of image elements. For each image element the surface coverage is determined by photoelectric measurements; a reference reflectance value is then calculated from these measurements, taking into consideration such parameters as the printing characteristic. These reference reflectance values are compared with the actual reflectance values measured on the printed products and the results of the comparison are evaluated to from a quality measure and to calculate control values for the ink feed devices of the printing machine. In this manner, the use of special color measuring strips may be eliminated.