Abstract: A system for coding photographic materials is provided wherein a code pattern disposed on a cassette containing photosensitive material is read by an optical code reading unit associated with a photographic apparatus adapted to receive the cassette. Preferably, a grey reference patch is provided and the code is a tertiary code defined by black, white and grey printed patches. The type of photosensitive material contained in the cassette is identified from the tertiary code and appropriate exposure and/or development settings can be made by the photographic apparatus. The absence of a recognizable code pattern indicates use of an authorized supply material.