TRANSILLUMINATE –To illuminate through a docu-
ment, from the side opposite the camera.
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.
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