Method for assessing the quality of a multi-color print image

US5947029A · kind A · utility

Assignee

• Heidelberger Druckmaschinen AG · DE

Inventors

• Gerhard Loeffler · Olsberg, DE
• Nikolaus Pfeiffer · Dover, US
• Manfred Schneider · Lichtenfels, DE

Key dates

• Filing date: Jan 29, 1998
• Grant date: Sep 7, 1999
• Expiry date: Jan 29, 2018

Classification

• Technology area (CPC G): Physics
• CPC primary: G06T2207/30144
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In a process for assessing the quality of a print image produced on a printing material in a multi-color printing process, in which signals which reproduce print-image elements are generated with an image-recording arrangement, in which color values are derived from the signals for every print-image element, in which the color values are transformed into color measures of a predetermined color space, in which color distances between an actual color site and a desired reference color site are determined for the print-image elements, correction variables of the control elements (18, 19, 20, 21), whose effect on a control element (18) would cause the actual color sites to be as close as possible to the reference color sites, are calculated from the color distances and stored in memory, that the color-distance vectors (.DELTA.L.sub.Bn, .DELTA.a.sub.Bn, .DELTA.b.sub.Bn) and color distances (.DELTA.E.sub.Bn) of at least one predetermined reference image (B.sub.n) with homogeneous area coverage are determined as a measure for the quality in the said print-image region, the correction variables (.DELTA.s.sub.B, .DELTA.s.sub.C, .DELTA.s.sub.M, .DELTA.s.sub.Y) which are necessary for compens…