Method for quality control of printed sheets

US5384859A · kind A · utility

Assignee

• KOENIG & BAUER AG · DE

Inventors

• Claus August Bolza-Schünemann · Würzburg, DE
• Johannes Georg Schaede · Würzburg, DE

Key dates

• Filing date: Aug 10, 1992
• Grant date: Jan 24, 1995
• Expiry date: Aug 10, 2012

Classification

• Technology area (CPC G): Physics
• CPC primary: G06T2207/30176
• WIPO field: Textile and paper machines
• WIPO sector: Mechanical engineering

Abstract

Individual printed image elements from an image to be inspected are allotted individual nominal ink density values, as by scanning an ideal printed sheet by a CCD matrix camera. The ideal values are stored in a main memory having segments for average, or grey, values for each image element. A multiplicity of proof images are scanned, and their density values measured and stored for each proof judged acceptable by an inspector. Thereafter, the variations in the acceptable proof density values are stored in the main memory as maximum and minimum acceptable deviations from the initial nominal values for each individual image element to provide a subjective tolerance value for the nominal density values in the main memory.