Photocopying – Projection printing and copying cameras – Multicolor picture
Patent
1986-06-06
1987-07-28
Wintercorn, Richard A.
Photocopying
Projection printing and copying cameras
Multicolor picture
G03B 2780
Patent
active
046828834
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
In general, this invention relates to the field of color exposure of photographic emulsion carriers when producing copies or enlargements of a film original and concerns a photographic color enlarging or copying apparatus having a measuring device for determining the density of a reference or test copy.
STATE OF THE ART ON WHICH THE APPLICATION IS BASED
The testing adjustment of a color enlarging apparatus with respect to a given film paper combination is not without difficulty and requires a considerable expenditure of time and material since as a rule, several attempts must be made and a number of test copies must be produced. The procedure in this case is usually that at first in a test exposure, a first test copy is made from a selected reference original that has a medium distribution of color and lightness and this test copy is visually evaluated. From the density errors and/or color errors that such a test copy usually has, the required corrections are determined empirically, and the adjustment of the enlarging apparatus is reset correspondingly. The process is repeated until a test copy has the desired quality and the adjustment that resulted in this picture is used as the basic adjustment of the enlarging apparatus for the other film frame originals to be copied.
The evaluation of the test copies and especially the correct assessment of possible color abnormalities in view of the determination of the type and extent of the required corrections requires a high degree of experience, and usually different steps are required until the desired result is achieved which in addition depends on the subjective judgment of an operator.
From DE-A-No. 33 31 136, a color copying apparatus is known that has a device for measuring the color density of a test copy made from a selected reference original and or a reference or target copy, in which case the exposure conditions are adjusted as a function of an existing difference of the measuring results between the test and the target copy. In this case, the picture copy to be measured is placed in the level for the original of the copying apparatus into the path of the copying rays and the density is determined by measuring the transmitted light coming out of the copy.
The density measurement in the transmitted light has the disadvantage that the measuring result can be influenced by the emulsion carrier of the used photographic material, resulting in the impairment of precision and reproducibility of the measurement. The copying light of the copying apparatus used as the measuring light has no constant characteristics and depends especially on the filtering of the originally white light of the copying light source required as a rule for a color adaptation so that the density measurement can be carried out only as a comparative measurement, and each measuring of a test copy must be accompanied by a measuring of the reference copy. Finally, the placing of the picture copy to be measured into the film carrier instead of the film frame original and its positioning in the measuring position is time-consuming and requires a certain attention on the part of the operator so that the testing adjustment of the copying apparatus by means of the known measuring device is relatively inconvenient.
DISCLOSURE OF THE INVENTION
It is the objective of the invention to provide a color enlarging or copying apparatus, in the case of which a precise and reproducible testing adjustment of the apparatus to a given film paper combination can be achieved on the basis of objective measurements in a simple way and without the requirement of special experience. The device according to the invention that achieves this objective has the characteristics listed in the characterizing part of claim 1.
The indicated invention makes possible the determination of the color density of picture copies in a simple and inexpensive way with a measuring precision that is inherent to the reflection densitometers and thus a rapid and precise determination of the basic adjustment of the e
REFERENCES:
patent: 4371259 (1983-02-01), Howitt
patent: 4492457 (1985-01-01), Kawada et al.
patent: 4572657 (1986-02-01), Amano et al.
Delueg Werner
Gandini Mario
Durst Phototechnik GmbH
Wintercorn Richard A.
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