Patent GB-547734-A (GB)
Abstract: 547,734. Colour photography. KODAK, Ltd. (Eastman Kodak Co.). Jan. 6, 1941, No. 183. Drawings to Specification. [Class 98 (ii)] In a photographic or photo-mechanical method of reproducing a multicolour original such as a coloured scene or a colour photograph, using masking images for colour correction, light of the three primary colours coming from the original is recorded in three light-sensitive emulsions on separate supports and the three colourrecord images are processed, light from the original of a colour or colours required for correction of one or more of the colour-record images is recorded in one or more emulsions on one or supports separate from that or those carrying the aforesaid emulsions for the colour records; and the correction record or records are processed to an image or images of opposite character to the colour-record images (i.e. to positive images if the colour-record images are negative, and vice versa) and serve as a correcting mask or masks when printing one or more of the colour-record images. The three colour records may be processed to negatives, and the correcting image or images may be formed in one or more direct-positive emulsions such as are described in Specification 524,087 in which use is made of the falling portion of the solarization curve. Ordinarily, no correction is necessary for the yellow colouring material used in the original or in the renroduction ; correction for the blue-green colouring material is made by masking both the green and blue record negatives by a positive made from the original through a red filter; and correction for the magenta colouring material may be made by masking the blue record negative by a positive made from the original through a green filter; and in this case the two masking operations on the blue record negative may be replaced by a single masking operation with a positive made from the original through a yellow filter, although the results are not exactly equivalent. Other variations are referred to in the Specification. By making use of either the shoulder, or the valley, of the falling portion of the solarization curve of the direct-positive material, or by using the whole of the falling portion provided that its latitude is sufficiently low, correction of the tonal qualities of the reproduction can be made. Both colour correction and tone correction can be effected if a positive mask made through a red filter is used in printing all three colour-record negatives ; or if a positive made through a magenta filter, or with white light without any filter, is used in printing the bluerecord negative. An example is described in which an original is photographed through blue, green and red filters to produce three colourrecord negatives on separate supports, and is also photographed through yellow and red filters on direct-positive material to produce two separate correcting positives, the exposures for these positives being made preferably through the supports. Two procedures are then possible. The yellow record positive may be used as a mask to print a corrected positive from the bluerecord negative, and the red-record positive as a mask to print a corrected positive from the green-record negative and also as a mask to print from the red-record negative a positive in which the tonal qualities are improved ; or, the redrecord positive may be used as a mask for all three negatives, the yellow-record positive being in this case dispensed with. The corrected positives so printed may be photographic films, washout relief matrices or on photo-mechanical printing plates. Specifications 353,151, 494,341, 501,661, 510,784, 512,608, 516,113, 516,514, 516,816, 517,020, 517,416, 537,864 also are referred to.