US 4,728,992 AGranted

Process and a device for adjusting a photographic color enlarging or copying apparatus

AssigneeDurst Phototechnik GmbH

InventorsAlex Vinatzer, Florian Vikoler

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Abstract

This invention relates to a process and a device for adjusting a photographic color enlarging or copying apparatus. By means of the measuring device that uses copying light of the enlarging apparatus to be adjusted as the measuring light, the color densities of a test copy made of a test original and of a reference copy which represents a satisfactory picture reproduction of the test original are measured selectively in the colors red, green and blue and are compared with one another. Corresponding to an existing deviation, adjusting control means at the enlarging apparatus that color-selectively influence the amount of copying light are readjusted until the deviation is balanced, and another test copy is made with the new exposure conditions and is measured.

Claims14

Dependent claims

A process for adjusting the color composition of the copying light of a photographic color enlarging or copying apparatus of the type having controls for adjusting the relative amounts of the basic colors red, green and blue in the copying light, said process comprising the steps of:

a. inserting a test original in the enlarging or copying apparatus, said test original having a gray patch of defined medium density;
b. providing an existing reference copy of the test original which reference copy represents a satisfactory reproduction of the gray patch of the test original;
c. inserting copying film in the film carrier of the enlarging or copying apparatus and exposing and subsequently developing the copying film to produce a test copy;
d. illuminating the test copy and the reference copy with the copying light of the enlarging or copying apparatus, and selectively measuring the amounts of red, green and blue light reflected by each of both the test copy and the reference copy;
e. comparing the measured red, green and blue light received from the test copy to the respective measured red, green and blue light received from the reference copy, and providing a visual indication of a deviation therebetween for each such color;
f. adjusting the color composition of the copying light for each of the three basic colors until the amounts of light in each color measured for the test copy and reference copy are in balance;
and
g. repeating steps (c) through (f) above until, following step (e), there is no longer a visual indication of a deviation between the amounts of the copying light reflected by the most recent test copy in the three basic colors red, green and blue and the corresponding amounts of copying light reflected by the reference copy.

5 more elements

A measuring device for adjusting the color composition of the copying light of a photographic color enlarging or copying apparatus, said measuring device utilizing a reference copy of a test original and test copies of the test original, the reference copy of the test original representing a satisfactory reproduction thereof, and the test copies of the test original being produced by successively exposing copying film to the test original using the copying light of the enlarging or copying apparatus to be adjusted, and developing the exposed copying film to thereby produce such test copies, said measuring device including in combination:

a. a housing;
b. a light measuring chamber formed within said housing;
c. receiving means disposed in said light measuring chamber for receiving and for positioning both the reference copy of the test original and a test copy of the test original;
d. light opening means communicating with said light measuring chamber, said light opening means being adapted to be guided into the copying light path of the enlarging or copying apparatus for admitting the copying light into said light measuring chamber and directing the copying light toward the reference copy and test copy positioned by said receiving means;
e. photoelectric transducers disposed within said light measuring chamber for receiving light reflected by the reference copy and by the test copy, said photoelectric transducers generating intensity-proportional electrical signals for each of the color components red, green and blue received thereby;
and
f. a measuring and indicating circuit coupled to said photoelectric transducers for providing a visual indication of deviations between the amounts of red, green and blue light reflected from the reference copy as compared with the respective amounts of red, green and blue light reflected from the test copy.

4 more elements

Dependencies are inferred from the claim text.