Fogged direct positive silver halide emulsions containing photographic sensitizing dyes derived from substituted salicylaldehydes

摘要

Cyanine and merocyanine photographic sensitizing dyes derived from substituted salicylaldehydes and light sensitive silver halide emulsions containing such dyes are disclosed. Also disclosed are certain reversible spiropyranmerocyanine dye systems, the stabilization of a dye in either the spiropyran form or the merocyanine form and observations of these photochromic materials when coated in polymeric matrices.