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Device for alignment of images in a control system for a printing press

  • US 5,816,151 A
  • Filed: 08/14/1997
  • Issued: 10/06/1998
  • Est. Priority Date: 09/29/1995
  • Status: Expired due to Term
First Claim
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1. A device for alignment of images for a control system of a printing press, comprising:

  • a black/white camera having a field of view;

    a color camera having a plurality of channels and a field of view;

    means for printing a pair of targets using an ink containing carbon black, with one of the printed targets having a grid pattern, and the other of the targets having an array of evenly spaced dots forming columns and rows;

    means for placing the target having a grid pattern under the camera field of view;

    means for displaying an image from the black/white camera and one channel of the color camera;

    means for adjusting the cameras to substantially align the two images;

    means for placing the dot pattern target under the camera field of view, and capturing images from the black/white camera and a single channel of the color camera;

    means for locating the actual X and Y position of each dot in each of the two images;

    means for calculating the average X position of each column and Y position of each row of dots, and determining the average spacing between columns and rows and the center point of the dot pattern;

    means for calculating a desired column and row spacing, and grid coordinates using the desired column and row spacing;

    means for adjusting the grid coordinates such that the center point of the grid is at the center point of the dot pattern;

    means for developing transfer functions which map the actual dot positions in that image to the desired dot positions; and

    means for capturing an image with the cameras, and performing a geometric transfer operation for each of the four images.

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