Abstract: A composition in the form of a dispersion in a hydrophilic continuous phase of a combination of N-vinylcarbazole, a halogenated hydrocarbon, 4-(p-dimethylaminostyryl)-quinoline as a sensitizer and a phenol derivative, as a shelf life extending additive, having the formula ##STR1## where R.sub.1 and R.sub.2 are individually C.sub.1 to C.sub.4 alkyl, and R.sub.3 is hydrogen, hydroxyl groups, C.sub.1 to C.sub.4 alkyl or C.sub.1 to C.sub.4 alkoxyl. The amount of the additive is in the range from 0.001 to 0.1 Wt% of N-vinylcarbazole.

Abstract: A film coated with a dispersion of an N-vinyl compound, an organic halogen compound and a sensitizer in gelatin is preheated at 60.degree.-120.degree.C before an imagewise exposure to sensitize the film and to destroy fog-nuclei. After the imagewise exposure the film is subjected to a red light flood exposure for intensifying latent image, heating for development and flood light exposure for fixing to give a negative image of high contrast. The preheating may be applied to a film once exposed to extinguish the resulting latent image and thereby to be subjected to another exposure.

Abstract: A light and heat sensitive composition useful particularly in photographic reproduction, the composition comprising a combination of an electron donative material, such as a .pi.-base and an electron acceptive material such as a .pi.-acid both dispersed in an aqueous dispersion medium in the form of discrete particles, at least one of the electron donative and electron acceptive materials being capable of polymerization upon irradiation by actinic light or an actinic corpuscular ray and the materials producing a colored charge transfer complex under predetermined heating conditions.