GB541266A - Improvements in methods of producing colour photographs employing colour correction - Google Patents

Abstract

541,266. Colour photography. KODAK, Ltd. (Eastman Kodak Co.). Feb. 17, 1940, No. 1023. [Class 98 (ii)] A colour or contrast corrected multicolour record is produced by exposing to a coloured object or a record thereof a photographic sensitive material comprising on one or both sides of a single support three inseparably-coated differently colour-sensitive emulsions in separate layer or mixed grain form, or in a combination of both forms, processing the emulsions to colour, and forming a colour-correcting mask, of lower maximum density than that of the multicolour record, in black-and-white or colour in the unused portion of at least one of the emulsions by one or more exposures to uniform light. Prints may be made from the corrected record. The emulsions may contain dye-forming substances, e.g. colour couplers. Preferably, material comprising several silver halide emulsions is developed to silver plus colour after the first exposure by colour production or colour suppression, the silver is removed by treatment which does not remove the residual silver halide or colour couplers (if present), or destroy the light sensitivity of the halide or the colour-forming capacity of the couplers, and the masking image is formed in the residual halide by one or more exposures to uniform light and development, which may be controlled, followed by fixing. if coloured light other than blue is to be used for the second exposure, the material must contain colour-sensitizing dyes which remain effective after the processing treatment preceding the exposure ; examples of such dyes are given in the Specification. The silver may be removed, for example, by bleaching with cupric chloride, and removing the resulting silver chloride with ammonia or ammonium sulphite ; or by the procedure given in Specification 516,514.; or by treatment with a bath containing potassium bichromate, sulphuric acid and sodium sulphate. An example is described in which material, after being developed to yield yellow, magenta, and blue-green component images, has a blue-green masking image formed in the unexposed portion of the emulsion containing the blue-green component image, thereby compensating for undue absorption for blue or green of the colouring substance of the blue-green component image; and a blue masking image in the unexposed portion of the emulsion containing the magenta component image, thereby compensating for undue absorption for blue of the colouring substance of the magenta component image. As the yellow component image rarely requires correction, it facilitates procedure in the case of multilayer material if the yellow image layer is disposed between the other two. A further example describes the production of a black-and-white masking image in the residual halide of all the layers of a three-layer material. Specifications 468,560, 478,933, 500,611, 512,608 and 517,416, and U.S.A. Specification 1,897,866 also are referred to.