Process for the preparation of a hybrid direct positive emulsion and photographic material containing such an emulsion.

摘要

A process is disclosed for the preparation of a hybrid direct positive silver halide emulsion comprising the steps of (1) forming an essentially cubic host grain emulsion consisting of silver bromide or silver iodobromide, with a iodide content between 0 and 10 mole %, by a balanced double jet, (2) depositing epitaxially on the corners of said formed essentially cubic host grains a silver iodide crystallographic phase wherein said silver iodide phase contains at most 5 % of the total crystal silver halide, either by precipitating a silver chloride epitaxial phase and converting it to silver iodide, or by adding silver ions and an organic iodide releaser. The organic iodide releaser is preferably mono-iodoacetic acid.