A method for forming a negative image comprising imagewise exposing a photographic material to provide exposed areas and unexposed areas, said material comprising, on a support, (1) an emulsion layer containing a light-sensitive silver halide, (2) unsensitized silver halide metallic salt grains which are more soluble in a developer than the light sensitive silver halide, and (3) nuclei for physical development, processing said material in the presence of a reducing agent and a solvent for said grains with said developer containing a substance which renders said grains less soluble by adsorbing thereto, said developer rendering said grains in said exposed areas and not in said unexposed areas soluble in said solvent, whereby metal ions are released and deposited on said nuclei.