The silver halide film emulsion is sensitive to ionizing radiation and light. A latent image is formed on the film by the absorption of a photon of energy that reaches the film. The energy of the x-ray or light photon interacts with the silver halide, creating a cascade aggregation of silver ions that form a complex large enough to form a latent image center. A latent image center is large enough to be visible following film processing. During radiographic film development, the silver atoms are reduced to metallic silver.
Metallic silver is black.
It is metallic silver that imparts blackness to the film. The same pattern of latent image formation occurs when film is exposed by visible light or x-ray photons. Film processing takes place in a darkroom, since radiographic film is very sensitive to light. Manual Film Processing Manual processing utilizes wet tanks in the darkroom. There are wet tanks for developing solution, a rinse bath, the fixing solution, and the final rinse.