Abstract: The specification describes a method for measuring the offset between regular images of, for instance, halftone dots and double images thereof, in which a test screen pattern is printed along an edge of the paper web to be printed which consists of two rows of test pattern strips representing a fishbone pattern. Using two sensors the gray values of the two test pattern rows are scanned and supplied to a double element printing measuring device. On the basis of the results of measurement and the geometrical relationships of the test strips and of the test edges arising owing to double printing phenomena the degree of double print offset may be determined. The method may be used for on line measurement of the degree of double print offset during the operation of the printing press.