GB516113A - Improvements in or relating to colour-photography - Google Patents

Abstract

516,113. Colour photography. DUFAYCHROMEX, Ltd., and CROOKS, D. A. May 19, 1938, No. 14994. [Class 98 (ii)] The contrast of a master multicolour transparency (positive or negative) is reduced by combining with it in register an inverse transparency mask (negative or positive) of reduced contrast, the mask being representative of all the colours of the master, and being either black and white or of a colour which does not transmit the colours of the master in a substantial degree; and from the combined master and mask a copy is printed of greater contrast than the combination, thereby compensating for the reduced contrast and producing a copy of good colour saturation. The master may be of the additive or subtractive type, or a combination of both types; and in particular it may be of the multicolourscreen type. The mask may be copied from the master on a separate or on an attached sensitive layer, or may be made at the same time as the master by making an independent exposure of the subject itself. The copy of the combination of master and mask may be made by first printing therefrom a set of colour separation records of greater contrast, and from these preparing a composite colour transparency or paper print, e.g., by the carbon process, or by photomechanical printing. Details are given of the procedure when using a multicolour-screen transparency as master. Specifications 446,679 and 494,341 are referred to. The Provisional Specification states that the mask, when coloured, may if desired be modified in colour, or may be printed by coloured light, to modify independently the colours of the master when combined with it.