Refers to still images produced from radiation-sensitive materials (sensitive to light, electron beams, or nuclear radiation), generally by means of the chemical action of light on a sensitive film, paper, glass, or metal. Photographs may be positive or negative, opaque or transparent. The concept does not include reproductive prints of documents and technical drawings, for which descriptors found under "<reprographic copies>" are more appropriate. The concept may include photographs made by digital means.

Source: Art & Architecture Thesaurus

http://vocab.getty.edu/page/aat/300046300