Optics: measuring and testing – By shade or color – Photography
Patent
1982-05-26
1984-08-28
Evans, F. L.
Optics: measuring and testing
By shade or color
Photography
355 35, 355 72, 355 77, G01J 346, G03B 2704
Patent
active
044681232
ABSTRACT:
The color balance of photographic printing paper is determined by making three successive exposures of the same portion of a sample sheet of photographic color printing paper. Two of the exposures are made through a neutral-color optical wedge of linear density gradient. The third exposure is not made through the wedge. Each exposure consists essentially of a different primary color of light of predetermined intensity and duration selectively to stimulate each of the three color-sensitive emulsion layers in the printing paper. The composite image produced upon development provides a means for visually matching a known color standard such as a neutral gray card to a definite small area of the print produced. The position of the discovered matching area of the print relative to a central point of the composite print, such central point being automatically demarcated in the procedure, provides a direct correction to the trial color analyzer printing program to produce a fully corrected printing program. An easel is provided for positioning the sample sheet of printing paper in proper relationship to the optical wedge, which can be keyed into place in an aperture in the light-proof cover. The wedge is removable and, when in place, may be revolved 90.degree. about the axis vertical to its plane at its density midpoint. Rotation is controlled by fixed stops.
REFERENCES:
patent: 3901598 (1975-08-01), Vanheerentals
patent: 4166701 (1979-09-01), Miller
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