Agfa Gevaert Nv

Marcel Jan Libeer

Raymond Gerard Lemahieu

Henri Depoorter

Frans Henri Claes

Gerrit Godfried Van Mierlo

Silver halide emulsions are prepared by silver halide precipitation in the presence of a reducing agent, physical ripening and, if desired, chemical ripening wherein subsequent to the addition of reducing agent and before the grains have reached their final size an oxidizing agent is added to the emulsion. By means of the reducing and oxidizing agents, the gradation and photosensitivity characteristics of the emulsion can be controlled at will.

Method of preparing photographic silver halide emulsions

The invention relates to a new class of pyrrolobenzimidazole, benzimidazoloisoquinoline and dipyrodinobenzodiimidazole in cyanine sensitizing dyes derived therefrom and their use in silver halide emulsions, and to methods for preparation of such new dyes.

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Mortsel, Belgium

Marcel Jan Libeer