GB112769A - Improvements in or connected with Color Photography. - Google Patents

Abstract

112,769. Hess-Ives Corporation, (Assignees of Ives. F. E.). Jan. 15, 1917. [Convention date]. Drawings to Specification. Colour photography; screens.-Three-colour records are produced as two negatives by recording two of the primary colours in one composite negative and recording the third primary colour in another negative; the negatives may be used to produce three separate coloured positives which are united to form a multi-coloured photograph. The negatives may be produced by means of two plates bound together with their sensitive surfaces inwards. The front plate has a two-colour screen between the base and the emulsion, the colours of the screen being preferably the secondary colours magenta and yellow, and the emulsion being insensitive to red, so that the images produced by exposure are records of the primary colours blue and green. The rear plate is sensitive to red. and, if it is also sensitive to blue and green, either stained red or has a thin red screen between it and the front plate, the image produced on it. which covers the whole plate, being a red colour-record. The magenta of the two-colour screen may be tinged with yellow, or a yellow screen may be employed at the lens to reduce the effect of the blue light. After ex. posure, the plates are separated and developed &c., and the rear negative is used to make a ferrocyanide or other blue-green positive. The composite negative is used first with a green screen to make a positive bearing a magenta image, and then with a blue screen to make a positive bearing a yellow image, and the three positives are afterwards combined. Alternatively the three positives are made successively on the same base. The positives may be dyed gelatine reliefs, and such reliefs may be used to make prints by imbibition. The two-colour screen may be made by coating the base with fine-grained gelatine, printing a carmine or magenta pattern on it with a greasy ink. and dyeing the imprinted parts yellow. The screen may have only one of its colours a secondary colour in which case the rear negative has a patterned image, and variations in the ratio between the areas of the colour elements may be made so as to secure any desired preponderance of tint.