image industrial radiography

What are different types of radiographic images?

Latent image: When light or X-radiation strikes a sensitive emulsion, the portions receiving a sufficient quantity of radiation undergo a change; extremely small particles of silver halide crystals are converted into metallic silver. These traces of silver are so minute that the sensitive layer remains to all appearances unchanged. The number of silver particles produced is higher in the portions struck by a greater quantity of radiation and less high where struck by a lesser quantity. In this manner a complete, though as yet invisible, image is formed in the light-sensiti- ve layer when exposure takes place, and this image is called the “ latent image”. Before and after exposure, but prior to development of the film, the latent image has a shiny pale green appearance.

Developing the latent image: Development is the process by which a latent image is converted into a visible image. This result is obtained by selective reduction into black metallic silver of the silver halide crystals in the emulsion. These crystals carry traces of metallic silver and in doing so form the latent image. Several chemical substances can reduce the exposed silver halides to metallic silver: these are called “developing agents”.