GB370908A - Improvements in or relating to colour photography - Google Patents

Abstract

370,908. Colour photography. TECHNICOLOR MOTION PICTURE CORPORATION, 110, Brookline Avenue, Boston, U.S.A.-(Assignees of Troland, L. T. ; 110, Brookline Avenue, Boston, U.S.A.) Jan. 12, 1931, No. 1043. Convention date, Feb. 1, 1930. [Class 98 (ii).] Colour photographs are obtained by simultaneously recording different colour aspects of a scene on different superposed layers of emulsion and subsequently dissolving off individually one or more image layers, prints being taken before and after each dissolving step to obtain individual colour records. The layers may have different solubility in the same solvent at different temperatures or in different solvents. Thus, for a two-colour film, a collodion emulsion is superposed upon a gelatine emulsion, the collodion layer being subsequently removed by alcohol or ether ; for three-colour films, three differentially-soluble gelatine coatings are employed or two differentially-soluble gelatine coatings with an uppermost collodion layer. In an example, the film base B is coated with a hardened gelatine emulsion P sensitized for red and blue and on this is coated a second gelatine emulsion S readily soluble in water at about 80‹ F. and sensitized for blue-green as with pinaflavol ; a filter coating F of congo red or rose bengal may be added. The film is exposed, developed and printed to give a composite positive after which the blue-green record is dissolved off with water leaving a red negative. An auxiliary duplicate negative is made from the composite positive and used to print a red-orange positive together with a bluegreen positive from the red negative. To obtain better colour separation, a negative print of the blue-green colour aspect is obtained from the red negative combined with the composite positive, and a green negative is obtained therefrom which is utilized with the red negative by any suitable process. A film suitable for three-colour work comprises an outer layer sensitive to blue and containing a yellow filter dye, a middle layer sensitive also to green and containing a magenta filter substance, and a support layer sensitive to red ; the outer layer is soluble in water at low temperatures, the middle layer in water at higher temperatures and the support layer is insoluble. Separate negatives of the three colour aspects are obtained by methods similar to that employed for the two-colour film.