Abstract: The invention relates to a method and a device for checking print products of the same kind, more particularly printed sheets of paper of the same kind, which are transported by a conveying device. For this purpose, during a teach-in phase, test images are recorded at a plurality of points on the print product by means of a digital camera. The test images recorded, or parts thereof, are analyzed with respect to their characteristic information, and the test image having the most distinct characteristic information is selected as the reference image. For the purpose of checking print products of the same kind, the subsequent print products of the same kind are checked by recording at least one image at a position corresponding to the reference image and by comparing it with the image data of the reference image.

Abstract: The invention relates to a method and a device for checking print products of the same kind, more particularly printed sheets of paper of the same kind, which are transported by a conveying device. For this purpose, during a teach-in phase, test images are recorded at a plurality of points on the print product by means of a digital camera. The test images recorded, or parts thereof, are analyzed with respect to their characteristic information, and the test image having the most distinct characteristic information is selected as the reference image. For the purpose of checking print products of the same kind, the subsequent print products of the same kind are checked by recording at least one image at a position corresponding to the reference image and by comparing it with the image data of the reference image.

Abstract: A method and apparatus for the detection of an edge of an object, with at least two photoelectric barriers, having at least one sender and at least one receiver apparatus as well as at least one common evaluation electronic unit for the detection of the edge or the presence of the object found on a transparent transporting belt. A diaphragm apparatus creates specially shaped light beam cross sections, wherein at least one light beam (B) is irradiated as a sufficiently narrow slit (5) in the direction of the edge to be detected, wherein the signals of the photoelectric barriers (3,4,10,11,12,13,14) are logically interconnected in the common evaluation unit (8).