Latent image

A latent image is an invisible photographic image formed when light changes a photosensitive material. Chemical development amplifies those changes into a visible image.

Silver halide: A light-sensitive silver compound used in photographic emulsions. Its crystals record exposure as microscopic chemical changes.
Photographic emulsion: A suspension of light-sensitive crystals in a binding layer, coated onto film or photographic paper. It is the medium in which a latent image forms.
Black-and-white film: Photographic film that records brightness as a monochrome image, usually through metallic silver. Its exposed silver-halide grains form a latent image that development turns into a negative.
Digital image sensor: An electronic device that converts incident light into electrical signals for image capture. It records exposure as electronic data rather than a chemically developed latent image.
Photolysis: A chemical reaction in which light breaks chemical bonds or triggers chemical change. Light initiates the changes that form the latent image in silver halide.
Silver-halide grain: A microscopic crystal of silver halide dispersed in a photographic emulsion. Exposure changes individual grains, which development later renders visible.
Color film: Photographic film that records color through multiple light-sensitive layers and dye-forming chemistry. Each layer forms a latent image for a different part of the color record.
Charge-coupled device: A semiconductor image sensor that transfers accumulated electrical charge to measure light. Its stored charge is an electronic exposure record, not a silver-halide image.
Latent-image center: A tiny cluster of silver atoms formed at an exposed site in a silver-halide crystal. These clusters mark exposed grains and help determine which crystals develop.
Photon: A quantum of electromagnetic radiation that carries energy. Absorbed photons provide the energy that initiates photographic exposure.

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