Patent GB-634169-A (GB)
Title: Improvements in or relating to the production of corrected photographic colour-component
IPC: G03C8/04
Filed: 1946-10-15
Abstract: 634,169. Colour photography. GEVAERT PHOTO-PRODUCTEN N.V. Oct. 15, 1946, No. 30686. Convention date, Dec. 5, 1942. Drawings to Specification. [Class 98 (ii)] Colour correction masks are produced by a process involving the transference of unreduced silver salt from a developed silver salt emulsion layer to a receiving layer in contact therewith and reduction of the transferred silver salt in the receiving layer to produce an image complementary in density to that in the emulsion layer. The image in the emulsion layer may be the image to be masked, and the image in the receiving layer may be coloured by colour development or by the dye-destruction process. The receiving layer may be replaced by grains containing the development nuclei and possibly the colour coupler or dye dispersed in the emulsion layer. In example 1, exposed material consisting of a support successively coated with a receiving layer containing development nuclei, green-recording orthochromatic silver salt emulsion layer of low silver content, a layer containing a removable yellow dye and preventing diffusion of silver halide from the succeeding into the preceding layer, and a blue-sensitive silver salt emulsion layer is developed in a developer containing hypo to produce a yellow highly-dispersed silver image in the receiving layer and green- and blue-component negatives in the emulsion layers. Development may be effected in a developer not' containing hypo followed by treatment with a silver salt dissolving agent, the diffused silver halide being reduced by residual developer. The receiving layer may be replaced by grains dispersed in the emulsion layer, and one or more intermediate layers may be used. In example 2, exposed material consisting of a transparent support carrying a receiving layer containing development germs or nuclei and a diffusionfast magenta coupler, a red-sensitive silver halide emulsion layer containing a diffusionfast blue-green coupler, a receiving layer containing development germs or nuclei and a diffusion-fast yellow coupler, a green-sensitive silver halide emulsion layer containing a diffusion-fast magenta coupler, a yellow colloidal silver filter layer acting also as a barrier layer, and a blue-sensitive silver halide emulsion layer containing a diffusion-fast yellow coupler is developed in a colour developer containing hypo and silver and residual silver halide is removed to give coloured negative images in the emulsion layers and masking coloured positive images in the receiving layers. In example 3, exposed material consisting of a support carrying a receiving layer containing a diffusion-fast or insolubilized blue-green azo dye, a red-sensitive silver halide emulsion layer containing a diffusion-fast red azo dye, a barrier layer, a receiving layer containing a diffusion-fast magenta azo dye, an orthochromatic silver halide emulsion containing a diffusion-fast yellow azo dye, a barrier layer, a receiving layer containing a diffusion-fast yellow azo dye, and a blue-sensitive silver halide emulsion is developed, fixed, treated in an imagewise dye-destruction bath, and silver removed to give negative coloured images in the receiving layers and positive coloured masking images in the first two emulsion layers. In example 4, exposed material consisting of a transparent support carrying a receiving layer containing a diffusion-fast blue-green coupler and colloidal silver serving also as an antihalation layer, a red-sensitive silver halide emulsion layer containing diffusion-fast magenta and yellow couplers, a barrier layer, a receiving layer containing a diffusion-fast magenta coupler, a green-sensitive emulsion layer containing a yellow coupler, a barrier layer containing colloidal silver serving also as yellow filter, and a blue-sensitive emulsion layer in which is dispersed colloid grains containing development nuclei and a yellow coupler is developed in a colour developer containing potassium thiocyanate to produce positive colour component images in the receiving layers and grains and negative coloured masking images in the red- and green-sensitized emulsion layers. Specification 614,155 is referred to.