(in radiology) a scale representing the possible gradient of densities from black to white for each pixel in an image. In an analogue image this gradient is smooth. A digital image has many discrete steps. The more steps allowed, the closer to representing the true analogue image it comes, although more steps require more computer memory. Images can be manipulated by windowing. This concept is particularly valuable in computerized tomography. see Hounsfield unit, digitization.
Subjects: Medicine and Health.