Photographic tone correction

• Main Author: HELLMIG ERHARD
• Format: Patent
• Language: English
• Published: 22.05.1962
• Subjects: ACCESSORIES THEREFOR; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USINGWAVES OTHER THAN OPTICAL WAVES; APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FORPROJECTING OR VIEWING THEM; APPARATUS SPECIALLY ADAPTED THEREFOR; AUXILIARY PROCESSES IN PHOTOGRAPHY; CINEMATOGRAPHY; ELECTROGRAPHY; HOLOGRAPHY; MATERIALS THEREFOR; ORIGINALS THEREFOR; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR,STEREO-PHOTOGRAPHIC PROCESSES; PHOTOGRAPHY; PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES,e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTORDEVICES; PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHYSICS

799,590. Tone correction of photographic images. AGFA AKT.-GES. [formerly AGFA AKT.-GES. FUR PHOTOFABRIKATTON.]. March 16, 1956 [March 19, 1955], No. 8331/56. Drawings to Specification. Class 98(2) A black and white or a monochromatic normal photographic image is combined with a coloured tone-correcting mask of colour different from that of the normal image, image and mask being either both positive or both negative, and these are copied by printing light absorbed by the normal image and usually partially absorbed by the mask on to a photographic layer sensitive to the light employed, whereby the light partially absorbed by the mask can be chosen to print the latter in desired gradation. The pair so printed may be separate or inseparably combined and printing may be in one step or separate steps for image and mask. In Example 1 a green-sensitized gelatino-silver bromide emulsion containing a specified magenta coupler on a transparent support is overcoated with a silver halide layer of 1/20th sensitivity of that of the inner layer and which is not optically sensitized but contains a specified yellow coupler, and this material is exposed in a camera to a black and white continuous tone image, colour developed, bleached and fixed with production of magenta image and yellow tone-correcting mask of specified relative gradations and printed on to an orthochromatic layer in two steps with blue and green printing lights respectively. The same effect can be achieved if the inner layer does not contain a coupler and the material is not bleached after development but only fixed, to produce silver and silver plus dye images respectively. Example 2 indicates production of a black and white silver image and a separate magenta coloured high-light image from a black and white continuous-tone image on a paper support, registration of the images so produced and printing thereof on to orthochromatic material as in Example 1. In Example 3 a multicolour negative is printed through a green filter on to two sheets of orthochromatic material, one of these is developed to form the normal black and white image and the other, of short exposure, is developedd to cyan, and these images are registered and printed through a screen on to a panchromatic layer using red and green filters successively, to result in copy for the production of a printing plate for the red partial image of multicolour printing. Example 4 describes production of a yellow high light image on a diazo layer from a black and white diapositive, registration of such with its original and printing or to carbon tissue.