The description of a film's photographic response to radiation of various wavelengths. Silver halides, the fundamental photosensitive elements of all photographic emulsions, are sensitive to high-energy radiations. However, they are sensitive only to the ultraviolet, violet, and blue in the visible and near-visible spectrum. Sensitizing dyes are commonly used to extend the sensitivity of an emulsion to the green, red, and near-infrared portions of the spectrum.
(of a photoreceptor) The sensitivity of a photoreceptor at each wavelength in the visible spectrum. For a given wavelength, this is equal to the ratio of the photoreceptor response at that wavelength to its response at the most sensitive wavelength. Different photoreceptor types have different spectral sensitivities.