A can inspection device includes a rotation device rotating cans, an imaging device taking images of rotating cans, and an image processor processing taken images. The imaging device includes a first camera taking an image of an entire can and a second camera taking an image of an opening-side end portion of the can. The image processor includes an image inspection means for inspecting whether printing is performed properly as compared with a master image by using the image taken by the first camera, a density measurement means for measuring densities in designated positions for respective colors by using the image taken by the first camera, and a printing misalignment value measurement means for measuring misalignment values with respect to set positions of printing misalignment inspection marks printed on the opening-side end portion of the can for respective colors by using the image taken by the second camera.

A method for operating a web printing press is provided. The method includes unwinding a substrate from a roll to define a web; during makeready, printing the web using at least one print unit, the makeready ending when the web is being printed to a desired standard; stopping the web after the makeready; rewinding the web so that the substrate printed during the make ready pass back through the print unit; and unwinding again the rewound substrate to pass through the print unit. A press and printed product are also provided.

An image processor 53 processing taken images includes an image inspection means 54 for inspecting whether printing is performed properly as compared with a master image by using the image of the entire can taken by a first camera, a density measurement means 55 for measuring densities in designated positions for respective colors also by using the image of the entire can taken by the first camera, and a printing misalignment value measurement means 56 for measuring misalignment values with respect to set positions of printing misalignment inspection marks printed on an opening-side end portion of a can for respective colors by using the image of the opening-side end portion of the can taken by the second camera.

A method for operating a web printing press is provided. The method includes unwinding a substrate from a roll to define a web; during makeready, printing the web using at least one print unit, the makeready ending when the web is being printed to a desired standard; stopping the web after the makeready; rewinding the web so that the substrate printed during the make ready pass back through the print unit; and unwinding again the rewound substrate to pass through the print unit. A press and printed product are also provided.

A device for measuring elevated areas of the surface of a rotary body in the form of a cylinder, a roller, a sleeve or a plate of a printing press, for example a flexographic printing plate, includes a first motor for rotating the rotary body about a rotational axis and a measuring unit for contactless measurement. The measuring unit for contactless measurement includes at least one radiation source and at least one area scan camera. The measuring unit for contactless measurement preferably includes a reference object, for example a wire tensioned in an axially parallel manner, a second motor and optionally a further second motor, for adjusting the measuring unit and/or the reference object perpendicularly to the rotational axis. The device makes it possible to measure elevated areas, for example flexographic print dots, quickly and with high precision. A system having the device is also provided.