Patent GB-513839-A (GB)
Title: Improvements in or relating to colouring processes
IPC: G03C7/18
Filed: 1938-01-20
Abstract: 513,839. Colour photography. OPTICOLOR AKT.-GES. Jan. 20, 1938, No. 1907. Void. Convention date, Jan. 20, 1937. [Class 98 (ii)] In a photographic process for the production of images or 'representations in colour, to be viewed either by reflection or transmission, by the superimposition of component subtractive colour images the dyestuff or pigment densities of which are proportional to the light intensities of the subject, the component images are so screened that the individual elements constituting each image differ in size in accordance with the brilliance values which the elements represent. As shown, a red colour-component film is wound from a spool 1 to a spool 1<1> under an autotype screen 2 and is printed by a red light source 3, for example, using a filter, on to a multilayer film wound from the spool 4 to the spool 4<1>. Similarly, the green colour-components film is wound from the spool 5, to a spool 5' under an autotype screen 6 arranged at an angle of 60 degrees to the first screen and is printed by a green light source 7 on to the multilayer film, and the blue colour-component film is wound from the spool 8 to a spool 8<1> under an auto type screen 9 arranged at an angle of 120 degrees to the first screen and is printed by a blue light source 10 on to the multilayer film, which is then colour-developed. In a modification, one layer could be printed with infra red light, the second with visible light, and the third with ultra-violet light. If the multilayer film is processed by the dye-destriction process, positive originals are used for printing. In another example, purple, blue-green, and yellow autotype screens are printed at angles of 60 degrees relative to one another or to a glass plate, and the multiple screen is secured at a small distance in front of the film during photographing. The film is colour developed, and may be printed with parallel light on to another multilayer film. The colours formed in the original may be any desired combination, and corresponding printing lights are used. If the multiple autotype screen is used only in copying, the screen colours are selected having regard to the sensitization of the printing film. The originals.may be separate or combined colour-component films lenticular films or multicolour screen films. Lenticular originals are printed by projection. A gradation curve is printed on the films with the aid of the screen using a grey wedge. The gradation may be influenced by diaphragms adjacent the light source or in the printing objective. Diaphragms of different form may be successively used, or filters having. zones of differing transparency, either greatest in the centre or decreasing towards the centre after an initial increase in transparency may be used. In another example, colour component originals may be developed to positives and printed with the aid of an autotype screen on to films bearing light sensitive gelatine, the gelatine being hardened at the exposed parts. The three images are then printed by imbibition in superimposition and in different colours on to a common gelatine-coated film. The images may be printed on paper, and the offset printing process may be used.