Novel photographic products and processes

Claim 2

A photographic film unit as defined in claim 2 which comprises a transparent support carrying on one surface a photosensitive silver halide emulsion consisting essentially of photosensitive silver halide crystals which contain at least two halides selected from the group consisting of iodide, bromide and chloride and silver precipitating nuclei dispersed in a processing composition permeable polymeric binder effective to substantially prevent microscopic diffusion of image components, said silver precipitating nuclei present in a concentration effective to provide upon development in the presence of a silver halide solvent, as a function of exposure of the unit to incident actinic radiation, a minimum image density not in excess of about 0.5 and a maximum image density of not less than about 2.0.

Claim 3

A photographic film unit as defined in claim 1 wherein said silver halide crystals comprise silver iodobromide crystals.

Claim 4

A photographic film unit as defined in claim 4 wherein said silver iodobromide crystals comprise about 1 to 9 percent, by weight, iodide. 6. A photographic film unit as defined in claim 4 which comprises a transparent support carrying on one surface a photosensitive silver halide emulsion consisting essentially of panchromatically sensitized silver iodobromide crystals and metallic sulfide, metallic selenide or colloidal noble metal silver precipitating nuclei dispersed in a gelatin binder in a concentration effective to provide upon development of exposed silver iodobromide crystals in the presence of a silver halide solvent, as a function of the point-to-point degree of exposure to actinic radiation, a maximum silver image density of developed silver derived from exposed silver halide crystals not in excess of about 0.3 and a maximum silver image density of developed silver derived from unexposed silver halide crystals of not less than about 2.4.

Claim 5

A photographic process which comprises, in combination, the steps of exposing a photographic film unit comprising a support carrying on one surface a photosensitive silver halide emulsion consisting essentially of photosensitive silver halide crystals which contain at least two halides selected from the group consisting of iodide, bromide and chloride and silver precipitating nuclei in a concentration effective to provide a silver image possessing optical density inversely proportional to exposure of the emulsion and contacting said silver halide emulsion with an aqueous processing composition containing a silver halide developing agent and a silver halide solvent to provide a visible silver image to said emulsion possessing optical density inversely proportional to exposure of the emulsion.

Claim 6

A photographic process as defined in claim 7 which comprises, in combination, the steps of exposing a photographic film unit containing a transparent support carrying on one surface a photosensitive silver halide emulsion consisting essentially of photosensitive silver halide crystals which contain at least two halides selected from the group consisting of iodide, bromide and chloride and silver precipitating nuclei dispersed in a processing composition permeable polymeric binder in a concentration effective to provide upon development, as a function of exposure, a silver image derived from development of unexposed silver halide crystals possessing a maximum image density at least 1.5 density units greater than the maximum density of the silver image derived from development of exposed silver halide crystals and contacting said silver halide emulsion with an aqueous processing composition containing a silver halide developing agent and a silver halide solvent for a period of time effective to provide a visible silver image to said emulsion in terms of the unexposed areas of said emulsion as a function of the point-to-point degree of emulsion exposure, said visible silver image derived from development of unexposed silver halide crystals and possessing a maximum image density at least 1.5 density units greater than the maximum density of developed silver derived from development of exposed silver halide crystals.

Claim 7

A photographic process as defined in claim 8 which comprises, in combination, the steps of exposing a photographic film unit which comprises a transparent support carrying on one surface a photosensitive silver halide emulsion consisting essentially of photosensitive silver halide crystals which contain at least two halides selected from the group consisting of iodide, bromide and chloride and silver precipitating nuclei dispersed in a processing composition permeable polymeric binder in a concentration effective to provide upon development of exposed silver halide crystals a maximum silver image density not in excess of about 0.5 and a maximum silver image density derived from unexposed silver halide crystals of not less than about 2.0 and contacting said silver halide emulsion with an aqueous processing composition containing a silver halide developing agent and a silver halide solvent for a sufficient time to provide a silver image to said emulsion comprising a maximum density of image silver derived from development of unexposed silver halide crystals of not less than about 2.0 and a maximum density of image silver derived from development of exposed silver halide crystals not in excess of about 0.5.

Claim 8

A photographic process as defined in claim 7 wherein said silver halide emulsion consisting essentially of a silver iodobromide emulsion.

Claim 9

A photographic process as defined in claim 10 wherein said silver iodobromide emulsion is panchromatically sensitized.

Claim 10

A photographic process as defined in claim 11 wherein said silver iodobromide emulsion consisting essentially of silver iodobromide crystals containing about 1 to 9 percent, by weight, iodide.

Claim 11

A photographic process which comprises, in combination, the steps of exposing a photographic film unit comprising a support carrying on one surface a photosensitive silver halide emulsion consisting essentially of panchromatically sensitized silver iodobromide crystals and silver precipitating nuclei dispersed in a processing composition permeable gelatin binder in a concentration effective to provide, upon development in the presence of a silver halide solvent and as a function of exposure, image silver derived from development of exposed silver iodobromide crystals possessing a maximum silver image density less than about 0.3 and a maximum silver image density derived from development of unexposed silver iodobromide crystals greater than about 2.4 and contacting said exposed emulsion with an aqueous processing composition containing a silver halide developing agent and a silver halide solvent for a time sufficient to provide a silver image to said emulsion in terms of the unexposed areas of said emulsion possessing a maximum silver image density of not less than about 2.4 and a silver image to said emulsion in terms of the exposed areas of said emulsion possessing a maximum silver image density not in excess of about 0.3.

Claim 12

A photographic process as defined in claim 13 wherein said silver precipitating nuclei comprises metallic sulfides, metallic selenides or colloidal noble metals.

Claim 13

A photographic process as defined in claim 14 wherein said silver precipitating nuclei are dispersed in said silver iodobromide emulsion in a concentration of about 1 to 25 X 10 6 moles/ft.2.