Patent GB-568440-A (GB)
Title: Improvements in photographic sensitive material and in colour correcting masks produced therefrom
IPC: G03C7/18
Filed: 1943-04-27
Abstract: 568,440. Photographic sensitive material; colour photograghy. KODAK, Ltd., and JONES, L. E. April 27, 1943, No. 6623. [Class 98 (ii)] The material comprises at least two emulsion layers which are inseparably coated on a support and are effectively sensitive either both to red light or both to green light, and which respectively contain colour couplers (including mixtures thereof) adapted to yield on colour development dyes of different colours. The emulsions may be of different gamma ; and a yellow decolorisable filter dye may be coated thereover. The material may be used in colour photography for producing coloured colour-correction masks of the kind described in Specifications 553,196, 553,229 and 553,230 where, for example, a single mask consisting of a single colour-component record is required to absorb light of more than one primary colour in predetermined relative proportions ; and the invention includes masks so made and the method of making and using them. Thus, material for making a colour-correction mask to compensate for undesired absorption of two colours (e.g. blue and green) by a cyan dye image in a colour original or a colour reproduction thereof may have two emulsions sensitive to red light and containing colour couplers which produce on colour development the required dyes (e.g. yellow and magenta) in the respective layers ; or, in the case of compensation for undesired absorption of two colours (e.g. blue and red) by a magenta dye image, the emulsions are both sensitive to green and contain respectively colour couplers yielding on colour development different dyes (e.g. yellow and cyan). Further, a material for making a correcting mask may comprise two such emulsions, one of which yields a coloured image intended to compensate for undesired light absorption, and the other of which is intended for contrast correction, of the image of which it is a record ; thus, there may be two red sensitive emulsions, one of which yields a dye image (e.g. magenta or yellow) for correcting undesired light absorption of a cyan image, and the other yields a cyan dye image for contrast correction of the first-mentioned cyan image ; or there may be two green sensitive emulsions one of which yields a dye image (e.g. cyan or yellow) for correcting undesired light absorption of a magenta image, and the other yields a magenta dye image for contrast correction of the first-mentioned magenta image. Also where contrast correction of an image is desired in conjunction with correction of the image for undesired light absorption of two colours, the material may contain for the purpose three red sensitive or three green sensitive emulsions on the same support, each containing an appropriate colour coupler. An emulsion intended for contrast correction is preferably of lower gamma than the emulsion or emulsions for colour-correction. The material may have an adhesive surface so that it may be secured to a multicolour transparency when making or using a mask. Examples of known sensitizers, filters, and colour couplers are given, and also of mixtures of couplers of the kind which yields on colour development a dye capable of absorbing light of two primary colours. Formulµ are also given for a colour developer and ferricyanide bleaching bath for use in processing the material. Specifications 427,516, 427,518, 427,520, 507,841, 524,154, 524,554, 524,555, 531,312, 537,921, 541,589 and 544,064 also are referred to.