GB865186A - Improvements in and relating to copying subtractive colour photographic films - Google Patents

Abstract

865,186. Copying colour films. CIBA Ltd. April 23, 1957 [April 23, 1956], No. 12983/57. Drawings to Specification. Class 98(2) Colour separation records are formed from a subtractive colour photographic film and the images therein, or to avoid damage of the original film in repetition work the images of a further set of separation records prepared from the first set, are formed into grainless dyestuff images in relief or tanned colloid material, and a copy of the subtractive colour film is formed from the latter images using light of very small aperture. The procedure avoids the scatter effect in copying silver images and has advantage of sharpness of outlines in the final copy as result particularly, of the images being in relief. Many methods of making such dye-relief or dye-tanned images are described briefly. A protective layer having a flat outer surface and of a material having a refractive index different from that of the material of the relief or tanned image may be provided, but this is described only with reference to Figures (not shown). Example 1 describes production of the records from a colour film using a pyrodeveloper, tanning bleaching bath, and dyestuff treatment; and the successive printing of these records with a bulb 33 centimetres therefrom on to positive three-layer film. Example 2 indicates production of three black and white colour separation negatives from a subtractive colour film, copying of the blue separation on to a fine grain bromide film, and then details the production of a colour relief image from the latter by a modification of the dye destruction process, with repetition of this for the original red and green separations, and successive printings in the manner of Example 1 for a final copy.