A diffuse transmittance spectroscopy method that utilizes a large-area photodetector in contact with the sample allowed the absorption spectra of reduction-sensitization centers and hydrogen-hypersensitization centers in AgBr emulsion to be measured using standard emulsion coatings. Both reduction-sensitization centers produced by dimethylamine borane and hydrogen-hypersensitization centers exhibited the common absorption band centered at 455 nm, shorter by ∼20 nm than that previously ascribed by other groups to similar reduction-sensitization centers in thick liquid layers of AgBr emulsions by means of diffuse reflectance spectroscopy.