GB819041A - Method of producing continuous-tone or half-tone copies which are corrected for toneand colour values - Google Patents

Abstract

819,041. Photographic tone and colour correcting masks. AGFA A.G. Sept. 5, 1956 [Oct. 20, 1955], No. 27198/56. Drawings to Specification. Class 98(2) A monochrome image is printed through a black and white tone-correcting, or a black and white colour-correcting, mask, with printing light at least partialy absorbed by the monochrome image as well as absorbed by the mask on to a photographic layer sensitive to such light. The effect of the mask relative to the monochrome image can so be varied as desired by choice of the colour of the printing light to produce a corrected print. Thus a continuous tone original may be exposed to a silver halide emplsion layer and the latter colour developed to a yellow-orange image, the same original exposed to record only the highlights on to a further silver halide emulsion layer and the latter black and white developed to form a mask, and then with monochrome and mask in combination, red light would pass unchanged through the monochrome and blue light would be strongly modulated thereby, but green light would produce a medium gradation therefrom. Following this procedure monochrome and mask may be produced on different supports or on the same support, and simultaneous or successive exposures with lights of different colour may be effected, and copying, enlargement 'or screening included in the procedure. In an example a black and white continuous tone image is printed on to a silver halide emulsion layer and the latter is processed to form a negative red monochrome image, and is exposed also on to an emulsion layer having a steep graduation so that only the high lights of the original are reproduced and processing is effected to produce a negative tone correcting mask. Monochrome and mask are then registered together and the relative effects of printing therethrough using a green and a red filter are described.