Ultrasonic image recording - image formation by measurement of ultrasound echoes translated electronically into a scanned visual image on a TV display. Also known as sonography.
Ultraviolet (UV) - part of the electromagnetic spectrum from about 400nm down to 1nm. It is invisible to the human eye, but most photographic materials are sensitive to near UV bands down to 250nm. It records as increased haze, particularly in distant views and at high altitudes, and may give a blue cast in color images. technique of projecting an infrared image on a phosphorescent surface.
Under-development - reduction in the degree of development. It is usually caused by shortened development time or a decrease in the temperature of the solution. It results in a loss of density and a reduction in image contrast.
Underexposure - result of too little exposure in the camera or at the enlargement stage.
Uprating - no longer used term to define the process of increasing the manufacturers film speed by the use of: hypersensitizing; using specially prepared proprietary developers; or by a two stage process.