| abstract |
Polymethine dyes, including cyanine, carbocyanine, dicarbocyanine, merocyanine and styryl dyes, are useful in direct positive photographic image-forming processes when included in a light-sensitive silver halide internal image emulsion. These dyes are N-substituted with alkyl groups whose terminal carbon atom is additionally substituted with 1-hydrazonoalkyl groups. They function both as spectral sensitizers and as nucleating agents. |