Method of controlling the quality of printed products by image inspection filtering

A method of controlling the quality of printed products, the method comprising:

• using a printing machine to always produce multiple printed products with an at least partially identical image content in a course of a print job to be completed;
• using at least one image sensor to record the multiple printed products and send the recorded multiple printed products to a computer as digital image data;
• using the computer to examine and assess the digital image data in an image inspection process to find print defects and to sort out printed products having been found to be unusable;
• using the computer to assess the identical image content of the digital image data of at least two consecutive printed products and only take into consideration such detected print defects being present on the at least two assessed consecutive printed products;
• subjecting detected print defects not being present in all of the at least two consecutive printed products to further analysis being at least one of an examination by an operator or a further analysis by the computer;
• and
• carrying out the further analysis by the computer by using the computer to form an average with respect to values of x and y positions and size in pixels of multiple print defects not being present in all of the at least two consecutive printed products and then, as a function of a result of a formation of an average, accordingly no longer taking these print defects into consideration.