GB820730A - Process for the production of duplicate copies from colour negatives or colour positives - Google Patents

Abstract

820,730. Photographic colour correction. AGFA A. G. Nov. 4, 1955 [Nov. 5, 1954], No. 31620/55. Class 98(2) Three processes for producing a duplicate copy from a subtractive multicolour transparency specify (1) printing through the latter in combination with a coloured corrective (defined as an optical combination of a colour separation record with another colour separation record of opposite but otherwise substantially the same gradation, both records being formed of dyestuffs of the same colour, this colour having substantially the same absoption as the unwanted absorption of the partial dyestuff images to be corrected and the colour separation records being produced in a single photographic layer or in separate photographic layers which may, if desired, be arranged on a common support), with white light and processing the result to a negative multicoiour image, printing through the latter together with a second coloured corrective which has been obtained by printing through the first coloured corrective, processing to a print of the same colour as this, and printing through the combined second multicolour image and second coloured corrective and processing to producing a multicolour image which is the desired duplicate copy; (2) printing through the combination as above but, instead of white light, using blue-green and red lights and separate emulsion layers sensitive thereto, processing the exposed layers to produce black and white colour separation records, printing these by the lights used to produce them on to multicolour material and processing to form the duplicate copy; (3) printing through blue, green and red filters respectively to produce black and white colour separation records, printing through multicolour transparency and the blue filter record with green light on to a green sensitive layer, processing this to black and white to form a "blue filter oorrective", printing through the multicolour transparency and this "corrective" and also successively through the other separ ation records on to multicolour material and processing this; if desired the green filter record also being provided with a corrective by printing it together with the original multicolour transparency with red light and processing to black and white. Three examples elaborate these three processes a little, and refer to Specifications 755,458 and 795,064 for production of the coloured corrective used in (1) and (2) above.