Patent GB-685607-A (GB)
Title: Colour photographic process
IPC: G03C7/18
Filed: 1949-02-23
Abstract: 685,607. Colour photography. GANGUIN, K. O., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Feb. 23, 1950 [Feb. 23, 1949], No. 4913/49. Drawings to Specification. Class 98 (ii). A multilayer film carries a colour photographic record comprising, in separate layers in any order, a yellow coloured colour-record image, a magenta coloured colour-record image, and a cyan coloured colour record image, the colours of two or three of which images are not complementary to the particular primary colours of the original object of which the images form records, and contains a black and white colour correcting mask in at least one of the layers carrying the magenta and cyan images. This coloured film is made by exposing and processing a false (or " unnatural ") colour multilayer film containing colour formers in the layers; a table showing all possible colourformer-sensitivity combinations for such, provided that the blue sensitive layer is uppermost, is furnished in the Specification; the coloured film may be printed on to a second material of similar type, the right colour-former-sensitivity combination of which may be selected from a second table, and the second material processed to a colour print or positive colour transparency. All processing may be by conventional methods, thus the black and white masks for the film may be produced by converting silver formed during colour development into a removable silver compound, removing this and selectively exposing residual silver halide in the layer carrying magenta or cyan or both such layers and treating with a black and white developer, or the difference in sensitivity between silver compound formed from the silver, and residual silver halide in the film may be used. A preferred arrangement is set out in a single example, in which a support is coated successively with a layer of red sensitive emulsion containing the sodium salt of 1-(3<SP>1</SP>-sulphomethyl-phenyl)-3- heptadecyl-5-pyrazolone as magenta colour former, a green sensitive emulsion containing the cyan colour former 1-hydroxy-2-naphthoylamino-2<SP>1</SP>-(methyl-octadecylamino)-benzene-5<SP>1</SP>- sulphonic acid, a colloidal silver yellow filter layer, and a blue sensitive emulsion containing the yellow colour former p-stearylaminobenzoylacetanilide-p<SP>1</SP>-carboxylic acid, sodium salt; exposed to light from a coloured object, colour developed, washed, bleached and washed again, re-exposed and developed in a p-hydroxyphenylglycine developer containing potassium iodide, washed, fixed and finally washed and dried, resulting in a coloured film with black and white positive image masks in the magenta and cyan coloured layers, and, because of development suppression in the upper layer by the potassium iodide, a yellow image only in this layer. Prints made from this on to a positive material with the same false-colour arrangement of layers show improved colour fidelity and saturation. In a further example in the Provisional Specification only re-exposure and second development are omitted, the coloured film is printed through a yellow filter on to a black and white panchromatic film, which is developed to a positive black and white transparency wash and prints are made from this and the coloured film in register. Specifications 486,848 and 489,162 are referred to.