Method and device for generating a digital lookup table for printing inks in image reproduction equipment

US5398121A · kind A · utility

Assignee

• Linotype-Hell AG · DE

Inventors

• Joern Kowalewski · Eschborn, DE
• Friedrich W. Vorhagen · Stolberg, DE

Key dates

• Filing date: Oct 23, 1992
• Grant date: Mar 14, 1995
• Expiry date: Oct 23, 2012

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N1/6019
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

The subject of the invention is a method and a device for generating a digital lookup table for printing inks in image reproduction equipment. Color scan values obtained by photoelectric scanning of an original are used for this purpose. The full colors of the three printing inks and white are measured. Model colors are determined which are in as linear as possible a relationship to the printing inks. This is achieved by a position of the chromaticity range of the print scale such that the primary stimuli of the model colors in the chromaticity diagram are each on one beam of the trajectories of the scale colors through the white point while the triangle set up between the primary stimuli encloses the chromaticity range of the print scale. The scale division of the primary stimuli is adjusted with a cube root to the printing inks. The number of fields to be scanned is determined on the basis of the measured values of the space diagonals. A cubic spline interpolation follows to generate the lookup table.