NOUVEAUX PROCEDES ET PRODUITS PHOTOGRAPHIQUES POUR L'OBTENTION D'IMAGESCOULEUR

1400792 Photographic process giving imagewise distribution of a reagent POLAROID CORP 20 June 1972 [21 June 1971] 28797/72 Heading G2C A photo-sensitive element comprising an exposed silver halide emulsion is developed with an aqueous alkaline processing composition to form in the undeveloped areas an imagewise distribution of soluble silver complex which is contacted with a compound capable of being cleaved in the presence of the complex to liberate a reagent and thereby form an imagewise distribution of the reagent, the reagent being a gelatine hardener, a development restrainer, a toning agent, an antifoggant, an aldehyde, a ketone or a silver halide solvent. The photo-sensitive element may have a sheet, which may comprise an image-receiving layer, attached to its support and overlying or capable of overlying the silver halide emulsion. The material may comprise a processing composition or the components thereof capable of being spread as a layer between the silver halide emulsion and the sheet. The processing composition may be an aqueous alkaline solution of silver halide solvent and developing agent. The compound may be in a layer between the support of the photo-sensitive element and the sheet when it overlies the emulsion or in the processing composition. One of the compound and liberated reagent may be diffusible and the other non-diffusible. Cleavage of the compound may result in the formation of one of the reagents and also a different compound that is a colour providing moiety or it may result in the formation of a colour providing moiety that is also one of the reagents. The process may involve diffusion of a soluble silver complex imagewise and liberation of a diffusible colour providing moiety e.g. a dye and a development restrainer or anti-foggant, the colour providing moiety diffusing to a receiving layer (see Fig. 1 not shown and Example 3). Alternatively, the imagewise distribution of soluble silver complex may diffuse to a material comprising a colour providing material and liberate (i) a diffusible colour providing moiety e.g. a dye thereby leaving in the material a dye image (see Fig. 2 not shown) or (ii) an aldehyde which is also a colour providing moiety which couples with a methylene coupler e.g. malononitrile to give a dye image (see Example 4). The compound may contain the group and may be a thiazolidine or benzothiazoline. The formulae of 36 dyes having cleavable thiazolidine or benzothiazoline nuclei are disclosed.