| 摘要 |
863,794. Copying in colour. GRETENER, E. June 26, 1957 [May 8, 1957], No. 20178/57. Addition to 791,676. Drawings to Specification. Class 40(3) Relates to a modification of the method described in the parent Specification for producing in a four-colour reproduction process a neutral colour separation image whose density at each point corresponds to the smallest of the three subtractive colour densities. This method involves the production by purely photographic steps of a first image, the basic image, whose density corresponds to a combination of the three colour components of an original, and the production by photoelectric point-by-point scanning of a second image, the correction image, whose density corresponds to the ratio of the greatest of the colour components to their sum (equivalent to the ratio of the smallest to the sum in terms of the subtractive densities). The neutral colour image is then produced by combining the basic and correction image. In accordance with the present invention the need to produce an intermediate photographic copy of the basic image is avoided. The neutral image is produced by direct photographic copying from an original three-colour transparency with the interposition in the light path as a mask a film carrying the correction image and produced as described in the parent Specification photo-electric scanning of the original. The spectral sensitivity of the copying light and the reproducing film is chosen so that, in the absence of the correcting mask, the neutral image would correspond to a combination (preferably the sum) of colour components in the basic image. Specification 791,675 also is referred to. |
