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. Underdevelopment is a 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 is the result of too little exposure in the camera or at the enlargement stage.
Universal developer is a name given to a number of developing solutions, usually MQ, indicating that they can be used for processing films and papers. Uranium Nitrate is a chemical used in toners and developers.