GB626979A - Improvements in color photography - Google Patents

Abstract

626,979. Colour photography. REPUBLIC PICTURES CORPORATION. Nov. 19, 1946, No. 34262. Convention date, Nov. 19, 1945. Drawings to Specification. [Class 98 (ii)] A photographic element for use in making transparent colour prints which has two layers of emulsion, as of gelatin, on one side of a base such as cellulose nitrate or acetate, each layer containing silver halide and a colour former, is characterised by the emulsions not being colour sensitised, whereby the light sensitivity of each layer is the normal sensitivity of the silver halide. The layers may be exposed from opposite sides of the element to colour separation negative records such as blue-green and orange-red printing negatives, colour developed to produce appropriate coloured images in both layers simultaneously, fixed and bleached to provide a positive colour print. Penetration of the printing light from one layer to the other may be prevented by effecting the exposures by ultra-violet light which has low penetrating power, or by use of a removable dye such as quinoline yellow in the emulsion layers or in a separate layer between them. Alternatively, such separate layer may contain silver particles produced as by exposure and development of light sensitive silver halide. A third colour image may be applied to the two colour print by imbibition. In a modification the element is provided with a further emulsion layer containing silver halide and a colour former between the other two layers, this layer being colour sensitised, for example to red light, and this layer is exposed first, from either side by red light which does not affect the other two layers to a third colour separation negative. The colour former in the colour sensitised layer may have no relationship to the colour sensitivity of that layer.