In a register error detection device, an image capturing unit captures an image of two first register marks of a first color printed on a substrate by a first plate cylinder of a rotary printing press and a second register mark of a second color printed on the substrate by a second plate cylinder of the rotary printing press. A calculation unit calculates a register error based on the number of pixels between a reference position located between the two first register marks and a comparison position that is based on the second register mark in the image captured by the image capturing unit.

A register error amount detection apparatus obtains the register error amounts between the colors of patterns printed on a printing product based on the positions of register marks in a captured image of the printing product. The register marks have different colors including a reference color and are printed in a line at intervals a in the vertical direction. The register marks all have the reference color and are printed in a line at the intervals a in the vertical direction at positions translated from the positions of the register marks by a distance b in the horizontal direction.

The present application provides an overprint orientation system. The overprint orientation system may include a first printer for printing on a substrate a first field and one or more orientation indicators within a second field, a second printer for overprinting the second field, and an orientation sensor. The orientation sensor determines whether the orientation indicators are visible.

Provided is a method of correcting printing misalignment in a printing apparatus that performs registration by using a printing misalignment inspection mark. This method is capable of improving registration accuracy and is capable of correcting the printing misalignment with higher accuracy. An image processor has printing misalignment value measurement means that measures a misalignment value with respect to a set position of the printing misalignment inspection mark that has been printed on an object. A printing misalignment inspection mark A is a hollow circle that is white inside, and the printing misalignment value measurement means measures the misalignment value with respect to the set position by using a white portion W of the printing misalignment inspection mark A.

The machine comprises: a plurality of printing units each of which has a printing cylinder movable so as to allow adjustment of the position of the image printed by that cylinder in two perpendicular adjustment directions relative to the web of printing material; first manually-operated adjustment means arranged to allow a user to adjust manually the position of each printing cylinder; image acquisition means arranged to acquire images of register marks printed by the printing units along one or both sides of the web of material; and display means arranged to show, on an enlarged scale, the images acquired by the image acquisition means, so as to allow the user to detect any misalignments between the register marks and to properly adjust the position of one or more printing cylinders to clear said misalignments. The image acquisition means comprise a plurality of cameras each of which is arranged to frame.

A method of evaluating print marks of detection objects using a print mark sensor and a print mark sensor for evaluating print marks having at least one light transmitter and at least one light receiver having a control and evaluation unit for evaluating the light receiver signal of the light receiver and having an output for a sensor signal that is formed by the control and evaluation unit on the basis of the light receiver signal.

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.

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.

The present invention relates to a method for controlling the operation of a printing press and a flexographic printing press for implementing said method, wherein the method comprises performing the following steps: a) capturing information from at least one image printed by said printing press; and b) comparing said information captured from said printed image with at least some digital-format information predetermined in prepress, or digital prepress information, including at least one part of the image to be printed. The method comprises adjusting the pressure and/or register setting of one or more printing units of the printing press, using at least the result of the comparison in said step b). The press is designed in order to implement the method.

The present application provides an overprint orientation system. The overprint orientation system may include a first printer for printing on a substrate a first field and one or more orientation indicators within a second field, a second printer for overprinting the second field, and an orientation sensor. The orientation sensor determines whether the orientation indicators are visible.