Method and apparatus for automatically recognizing photographic originals unsuitable for copying

US4239384A · kind A · utility

Assignee

• Agfa-Gevaert NV · BE

Inventor

• Helmut Treiber · Munich, DE

Key dates

• Filing date: Nov 29, 1978
• Grant date: Dec 16, 1980
• Expiry date: Nov 29, 1998

Classification

• Technology area (CPC G): Physics
• CPC primary: G03B27/72
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A negative whose printability is to be automatically ascertained is subdivided into a central zone, a foreground zone, and a background zone. Whole-zone density signals are produced for the foreground and background zones, and the central zone is scanned to generate a maximum-density signal indicating the density of the maximum-density point within the central zone. The negative is rejected for being underexposed when both of two conditions are met: first, the larger of the foreground and background whole-zone density signals fails to exceed a first limit value; and second, the difference between the central-zone maximum-density signal, on the one hand, and the smaller of the foregound and background whole-zone density signals, on the other hand, fails to exceed a second limit value. The negative is rejected as overexposed when the average of the foreground and background whole-zone density signals fails to exceed a third limit value, irrespective of the density of the central zone. The negative is rejected as containing a meaningless motif, e.g., an adhesive sticker applied to the negative, when the central-zone maximum-density signal exceeds a fourth limit value, the density corr…