Patent GB-539228-A (GB)
Title: Color photography
IPC: G03C7/00
Filed: 1939-12-29
Abstract: 539,228. Colour photography. TECHNICOLOR MOTION PICTURE CORPORATION. Dec. 29, 1939, No. 33030. Convention date, Feb. 27. [Class 98 (ii)] In a method of making three-colour records involving printing with light of selected colour from super-imposed component records in subtractive dyes of which one or several absorb light which should properly be absorbed only by a dye of another record, an image-bearing beam L is divided, and a colour record whose range corresponds to a dye having undesired absorption is made on a single film G in one component beam R, and the two other colour records are made on a single film IP bearing two superimposed emulsion layers in the other component beam S, whereafter the super-imposed latent records on the film IP are converted into subtractive dye records, each of these records is printed with selectively-coloured light, and the record on the film G is separately printed. The film IP may record the green and blue, or the red and blue. The three records are preferably processed to colours complementary to those which they record, and may be printed on to a single support photographically by methods using initially coloured or uncoloured emulsion layers, or by imbibition. A duplicate printing pair, similar to the original pair of films, may be made if desired. In the embodiment shown, the film IP comprises a blue-sensitive layer BL and a red-sensitive layer RL, both preferably uncoloured and separated by a minus-blue filter FMB. A minus-green filter MG may be placed in front if layer RL has unwanted green sensitivity. The film G is green-sensitive with an interposed green filter GF. After exposure, the images are developed to colours complementary to those which they record. The records are then printed, preferably first to produce duplicates of the two films, the minusgreen image on G being printed on a single-layer film and developed to minus-green, and the two images on IP being printed on a two-layer film, the minus-blue image with blue printing light, and the minus-red with red printing light, and the images are developed respectively to minus blue and minus red. From either the original records or the duplicate records a tricolour positive may be similarly printed onto material comprising three emulsion layers on a single support, e.g. all uncoloured and all on one side, or having a green-sensitive layer on one side and on the other a blue-sensitive layer over a red-sensitive layer with an intermediate minusblue filter, all the layers containing agents which yield the desired colours on colour development. In an alternative method, negatives on separate supports are printed from the original or duplicate images, and are either printed or reversed to yield positives on separate supports; and these positives may be used in any way for further reproduction, e.g. on multi-layer material, but are preferably formed as gelatin reliefs to be used as matrices for printing the records by dye inbibition into a single layer, e.g. as in Specification 307,659, [Class 98 (ii)]. Specifications 373,429, 374,849, 375,338, 382,239, 428,422, 484,698, and 500,721 also are referred to.