A measure of the speed of colour film; used in digital cameras to indicate the camera's sensitivity to light. Sensitivity is measured using ISO ratings (ISO 100, ISO 400, ISO 800, etc. ); the higher the number, the more sensitive ("faster") the film or image sensor and the less time or aperture needed to make an exposure. High-speed films tend to be "grainy," while the gain used to boost the sensitivity of image sensors tends to generate more noise artifacts. To avoid confusion with other senses of the word "sensitivity," "ISO sensitivity" is preferred.