Verfahren zur Herstellung photographischer Bilder

1283218 Direct-positive silver halide material and process EASTMAN KODAK CO 5 Sept 1969 [9 Sept 1968] 44082/69 Heading G2C A sensitive photographic material comprising a layer of a blue-sensitive direct-positive silver halide composition of which the silver halide comprises at least 50 mole per cent of silver chloride is exposed and treated with a 'lith' developer (i.e. one that contains a polyhydroxybenzene developing agent) in the presence of an alkylene oxide polymer or derivative thereof. The invention also comprises a material as defined above wherein an alkylene oxide polymer or derivative thereof is incorporated in the emulsion layer or an adjacent water-permeable layer. The polymer is preferably derived from ethylene, propylene or butylene oxide, most preferably ethylene oxide and may contain at least 4 ethylene oxide units. The ethylene oxide moiety may have an average molecular weight of 300 to 4000. The polymer may be a block copolymer of polyoxyethylene and polyoxypropylene containing from 10 to 70 per cent by weight of the polyoxyethylene units, the average molecular weight of the polyoxypropylene moiety being between 800 and 3000 or a water soluble organosilicone polyalkylene oxide polymer. The emulsion may contain an electron accepter e.g. a sensitizing dye, and/or a BSI compound (defined in Specification 1186718) e.g. a merocyanine dye. The material may contain an anium salt or a 3-pyrazolidone which increases the development rate. The use of the alkylene oxide polymer or derivative thereof increases the contrast of the images produced.