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Proceedings Paper

Minitargets: a new dimension in print quality control
Author(s): Hansjoerg Kuenzli; Freddy Deppner; Karl Heuberger; Yufan Jiang
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Paper Abstract

Running a printing press requires frequent measurements in order to achieve and maintain an acceptable level of print quality. Ideally, on-line measurements should be made within an image and automatically used to adjust the inking system to achieve and maintain the desired target values. However, there are still several obstacles to this approach. As an intermediate solution, we have developed a system for quality control in newspaper printing, consisting of a mini-target, an optical device, and a three chip CCD camera. The measurements are made off-line. Individual prints are analyzed from which the behavior of the printing press can be studied. The mini- target was minimized to approximately 1/9 of a square inch, which is more than a magnitude smaller compared to control strips commonly used. The mini-target contains areas of solid tone, halftone and elements for register control. Due to its small dimensions it is accepted in newspaper printing. The CCD camera is a commercially available 3 chip 8-bit camera. Using the camera and image analysis software which has been developed, we are able to measure registration, solid-tone density, dot gain and colorimetric values. A measurement is performed by capturing the image of the test target in one shot followed by image analysis. The reproducibility of the system is high. Misregistration can be determined in the range of plus or minus 200 micrometers with an accuracy of about 20 micrometers.

Paper Details

Date Published: 2 January 1998
PDF: 6 pages
Proc. SPIE 3300, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III, (2 January 1998); doi: 10.1117/12.298291
Show Author Affiliations
Hansjoerg Kuenzli, Swiss Federal Labs. for Materials Testing and Research (Switzerland)
Freddy Deppner, Swiss Federal Labs. for Materials Testing and Research (Switzerland)
Karl Heuberger, Swiss Federal Labs. for Materials Testing and Research (Switzerland)
Yufan Jiang, WIFAG (Switzerland)


Published in SPIE Proceedings Vol. 3300:
Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III
Giordano B. Beretta; Reiner Eschbach, Editor(s)

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