SURFACE DEVELOPMENT OF AN IMAGEWISE EXPOSED EMULSION CONTAINING SILVER HALIDE GRAINS WITH CORES CHEMICALLY RIPENED IN TWO STAGES

摘要

Light-sensitive silver halide emulsion adapted for producing either negative or direct positive photographic images and containing composite grains of silver bromide having internal core portions of chemically ripened silver bromide and external shell portions surrounding such core portions of chemically fogged silver bromide, such emulsion on development with a surface developing agent having a characteristic curve which exhibits a knee portion connecting a generally rectilinear portion of positive gradient and a generally rectilinear portion of negative gradient and is preferably of generally symmetrical configuration. By adjustment of the magnitude of the exposure of the emulsion to light either a direct positive or a negative photographic reproduction is obtained.