GB709559A - Improvements in or relating to colour photography - Google Patents

Abstract

709,559. Colour photography. CLARKE, T. G. Jan, 21, 1952 [Oct. 21, 1950; Nov. 10, 1950], Nos. 25699/50 and 27476/50. Class 98(2) Paper or film is successively sensitized, or resensitized with a light sensitive emulsion, exposed to different colours of a colour image, record or object, and developed to colour, the images being produced in a multiplicity of dots by applying the emulsion in dot form, or by applying the emulsion as a continuous coating and breaking up the images as by use of a half-tone screen during exposure. The emulsions may be transferred to the paper or film from tissues prior to each exposure step; or the dot emulsions may be applied from .a multiplicity of bosses on, or recesses in, a plate or roller, or by use of a stencil as of perforated metal foil. The dots may be applied in rows in angular relationship to each other. The emulsions may be of sensitized pigmented gelatine comprising successively yellow, red and blue pigments and development effected by insolubilization of exposed areas and removal of soluble gelatin; or of silver bromide type with development in a tanning developer followed by washing in warm water and dyeing of the remaining relief images, or colour or dye toning, or colour development procedure may be used. Registration may be effected when using a colour negative by providing a locating mark such as a cross or dot at each corner thereof, which marks are transferred to the emulsion photographically at the first exposure and used, with an opaque mask over the emulsion except for the edges, to locate the negative for subsequent exposures and for this locating operation the emulsion may be secured to a backboard with a steel base and held on a supporting surface provided with permanent magnets. After each step of colour formation a protective transparent varnish or film coating may be applied. It is stated that bromide prints from three separation negatives may be brought in turn into contact with paper having a sensitized coating, with development and dyeing of the resulting relief images, unless an appropriately sensitized coating has been used, in place of exposure.