Direct-positive double exposure process utilizing a primitive, unfogged silver halide emulsion containing an electron acceptor

Claim 1

A process for producing a direct-positive image in a silver halide photographic element comprising 1. imagewise exposing for at least 0.01 second at an intensity of at least 1 × 10.sup. -12 watt/cm 2 a photographic element comprising a support and coated theron at least one layer of a primitive, silver halide emulsion which contains 1 mg to 2 grams per mole of silver of an electron-accepting compound having a cathode halfwave potential more positive than -1.0 volt and an anodic halfwave potential more positive than +0.4 volt, said emulsion being derived from precipitation of an alkali metal halide and a water soluble silver salt in contact with a peptizer and in the absence of chemical or physical sensitizing conditions, the silver halide emulsion in the absence of exposure exhibiting a density of less than 0.3 when processed for 5 minutes at 27° C in a photographic developer having the following composition: ______________________________________ water 500.0 cc N-methyl-p-amino-phenol sulfate 2.0 g sodium sulfite 90.0 g hydroquinone 8.0 g sodium carbonate, monohydrated 52.5 g potassium bromide 5.0 g water to make 1.0 liter ______________________________________ 2. exposing said imagewise-exposed silver halide emulsion to an overall flash for less than 0.05 second at an intensity at least 10 times greater than the imagewise exposure and 3. developing said photographic element in silver halide surface-image developer which is substantially free of silver halide solvent.