Gretag Systems, Inc.

Ciba-geigy Corporation

Werner R Von Stein

Walter Kraft

Process wherein the slope of linear segments of color density curves of color copy material are affected in a controlled manner by homogeneous supplemental exposures. The quantities of light required for the supplemental exposures are determined by the analysis of the spectral density values of the copy master and by comparison with the color density curves of the copy material.

Process for the preparation of photographic color copies from copy

The copy originals are scanned photoelectrically by regions and three color densities are determined for each scanning regions. Additionally, using a high resolution scanning system, a detail contrast parameter describing the detail contrast in the scanning region is determined. The detail contrast parameters are evaluated together with the color densities of the scanning regions for the determination of the copy light quantities. In particular, in the correction of densities, scanning regions with higher detail contrasts are considered stronger than those with lower density contrasts, while color corrections are carried out in exactly the opposite manner.

Exposure control process and photographic color copying apparatus

Originals to be copied are scanned spectral photometrically by regions and from the spectral values obtained thereby, color extract values adapted to the spectral sensitivity variations of the copy material are formed by electronic or computer filtering. The color extract values are then evaluated for the determination of the necessary amounts of copying light. The spectral values are simultaneously used for image analysis and additional control of the exposure. The process avoids expensive optical filters and makes an image analysis which yields a greater amount of information, and thus a more extact determination of the amounts of copying light, possible.

Growing community of inventors

Hamburg, Germany

Werner R Von Stein