UNDERDEVELOPMENT Insufficient development; due to developing for too short a time, use of a weakened developer or, occasionally, too low a temperature.

UNDEREXPOSURE Insufficient exposure of a photographic material, causing thin or weak images and a corresponding loss of detail. (PIA)

VANISHING POINT In a perspective view, the point where parallel lines receding from the observer seem to come together.

VELOCITY OF LIGHT Term applied to the speed of light waves in a vacuum (Co); 229,792.5 kilometers per second, or approximately 186,000 miles per second. In all other media, light travels at a slower rate.

VIDEO CASSETTE A plastic container in which a videotape moves from a supply reel to a take-up reel. Used in all but the 1-inch VTRs.

VISIBLE SPECTRUM The portion of the electromagnetic spectrum to which the retina is sensitive and by which we see. Extends from about 400 to 750 millimicrons in wavelengths of radiation.

VTR Videotape recorder or recording. Includes video cassette recorders.

WASHING Act of removing soluble chemicals from photographic layers through the agency of water, especially the removal of fixation products and hypo in order to avoid subsequent fading or discoloration of the silver image.

WATER SPOTS Deformation of photographic gelatin layers on a film or plate due to differential drying when water drops stand on the surface and keep the gelatin wet and swollen after the surrounding gelatin has become dried and compressed. The spots have a characteristic appearance when a negative on which they occur is printed. Viscose sponges and wetting solutions (detergents) are commonly used to avoid such defects. (PIA)

WAVELENGTH Length of a wave measured from any point on one wave to the corresponding point on the next wave; usually measured from crest to crest. Wavelength determines whether radiant energy is classed as gamma rays, X rays, or ultraviolet, visible, infrared radiant energy, or radio. Wavelength of visible radiant energy is the chief determinant of its perceived color.

WETTING AGENT A chemical added to water to reduce surface tension, thereby improving wetting characteristics and reducing the formation of water drops. (NMA)

Y/C The separate processing of the luminance (Y) and chrominance (C) signals.