A sheeter which can cut a running printed sheet discharged from a web-fed rotary gravure press, a web-fed rotary forms press, or similar rotary press with higher accuracy is provided on-line. The sheeter can selectively carry out a change in the length of cut with the change of a printing plate cylinder. A drum roller, which has the same diameter as that of the plate cylinder in a printing unit or a diameter that is enlarged by an amount of the applied tension, is provided in such a way that it is exchangeable and lies on a sheet guide passage introducing the running printed sheet to a cutting section with the flying knife. The drum roller is rotationally driven synchronous with the plate cylinder by a driving shaft of the plate cylinder, and feeds the running printed sheet to the cutting section by winding it. When exchanging the plate cylinder, the existing drum roller is exchanged with another which has the same diameter as that of the plate cylinder to be changed or a diameter enlarged to compensate for the amount of applied tension.

A process is provided for determining the position of a printed paper web in a printing press, especially in a rotary printing press. Reference values for determining the position from the image data of the preliminary printing stage are obtained. At least part of a printing style on the paper web is detected by at least one scanner. The reference values obtained from the image data of the preliminary printing stage are compared with the measured values detected by at least one sensor. The position of the printed paper web is determined from the result of the comparison. A device is provided for determining the position of a printed paper web in a printing press, especially in a rotary printing press, with a data processing device, in which reference values are generated from image data from the preliminary printing stage for determining the position. At least one sensor is provided for detecting at least part of a printing style on the paper web. A comparing device compares reference values and measured values with one another in order to determine the position of the printed paper web therefrom.

A method and apparatus is disclosed for digitally compressing video signals. The method and apparatus provides a system which generates values related to the differences between respective pixel locations and an x,y pixel display. The differences generated between proximate pixel locations are used to generate various delta values which are encoded in an asymmetric fashion. The asymmetric coding eliminates artifacts in the displayed image, and the delta encoding is performed in both a horizontal and vertical direction (otherwise known as Two-Dimensional Delta Encoding) and this operation tends to randomly distribute error in the compression process across the visual image so as to approximate noise or grain generally perceived by the viewer in an analog display.

A system for controlling an apparatus operating on a moving web, in accordance with a periodic characteristic of the web. Indicia of successive periods of the characteristics are generated and compared to generate control signals to the apparatus. Specifically, a cutoff control system for a web-fed printing press is disclosed wherein the effective position of the cutting apparatus along the weg path is varied in accordance with variation in the position of a maximum density change in an individual repetitive image from that of a reference image, or in accordance with a cross-correlation between the individual image and a reference image.

The invention provides a cutoff control system having a capture range equal to the length of the image (signature) which is highly tolerant of spurious transitions, such as lateral shifting and instantaneous interruptions of the web. A highly pipelined hardware correlation unit, cooperating with several high speed RAM devices having independent address generators, is used to cross-correlate new patterns with a reference pattern. An illustrated system for relating a cyclical machine operation to the position of images on a web includes position adjustment means (24,30,84) responsive to control signals for varying the effective position of the machine operation along the moving web, means (34,40,50) for generating image signatures indicative of the image at respective sampling intervals during the matching operation cycle for respective machine cycles, means (56,58,68,72) for selectively generating reference pattern indicia from a first image signature and for selectively generating comparative indicia from a successive image signature, means (71) for generating correlation cooeficients in accordance with the differences between the reference pattern and shifted versions of the comparative indicia, means (68,69,70) for processing the correlation coefficients to determine which of the comparative indicia produced the largest correlation coeficient and generating an indicating signal in response thereto, and means (80) for generating the control signals to the position adjustment means in accordance with the indicating signal.