Direct positive silver halide reversal film - using integral image type silver halide grains developed in surface developer and di:phenylmethane type nucleating agent

Photographic process for producing a reversal image and silver-halide emulsion for producing reversal images are claimed, the photographic material used comprising at least one internal latent image type silver halide emulsion layer which after exposure is developed using a surface developer in the presence of a diphenylmethane type nucleating agent (I) to cause development of silver halide in the unexposed areas and thus to give a positive image w.r.t. the original (I) pref. has the formula (Ia) in which Z1 and Z2 complete phenyl rings, R1 is H or 1-6C alkyl, and R2, R3 and R4 each represent H, halogen, alkyl, alkoxy, OH, aryl, alkaryl or aralkyl, or R3 and R4 together represent covalent bond, -O-, -S- or -C(R1)(R2)- in which R1 and R2 are 1-6C alkyl or 6-10C aryl. The silver halide grains used have a high ratio of internal to external sensitivity, so that the surface developer does not develop the latent image formed in the interior of the grains. In the unexposed portion,s the Ag halide grains are rendered developable by the presence of (I), the action of which is inhibited in the exposed protions, and silver development takes place in the unexposed regions to form a direct positive image. LA PRESENTE INVENTION EST RELATIVE A LA PHOTOGRAPHIE.LE PROCEDE SUIVANT L'INVENTION CONSISTE A EXPOSER SUIVANT UNE IMAGE UN PRODUIT PHOTOGRAPHIQUE COMPRENANT AU MOINS UNE COUCHE D'EMULSION AUX HALOGENURES D'ARGENT A IMAGE LATENTE INTERNE, POSITIVE DIRECTE, NON VOILEE, PUIS A DEVELOPPER CE PRODUIT PAR UN REVELATEUR SUPERFICIEL, EN PRESENCE D'UN AGENT DE NUCLEATION DE LA CLASSE DU DIPHENYLMETHANE, DE MANIERE A OBTENIR LE DEVELOPPEMENT DES HALOGENURES D'ARGENT DANS LES PLAGES NON EXPOSEES ET A FORMER UNE IMAGE POSITIVE PAR RAPPORT A L'ORIGINAL. CE PRODUIT PHOTOGRAPHIQUE PEUT COMPRENDRE, EN OUTRE, UN COUPLEUR FORMATEUR DE COLORANT ET DONNER, APRES TRAITEMENT CHROMOGENE, UNE IMAGE DE COLORANT POSITIVE PAR RAPPORT A L'ORIGINAL.APPLICATION A L'OBTENTION D'IMAGES PHOTOGRAPHIQUES POSITIVES DIRECTES PRESENTANT UNE FAIBLE DMIN ET UNE DISCRIMINATION ELEVEE.