EM 1110-2-2907
1 October 2003
Contact print
A reproduction from a photographic negative in direct contact with
photosensitive paper.
Context
The known environment of a particular feature on an image.
Contrast
The ratio between the energy emitted or reflected by an object and its
immediate surroundings.
Contrast enhancement
Image-processing procedure that improves the contrast ratio of images.
The original narrow range of digital values is expanded to utilize the full
range of available digital values.
Contrast ratio
On an image, the reflectance ratio between the brightest and darkest
parts of an image.
Contrast stretching
Expanding a measured range of digital numbers in an image to a larger
range, to improve the contrast of the image and its component parts.
Transfer of heat through the physical movement of matter.
Corner reflector
Cavity formed by two or three smooth planar surfaces intersecting at
right angles. Electromagnetic waves entering a corner reflector are
reflected directly back toward the source.
Corps
US Army Corps of Engineers (USACE)
COSMIC
Computer Software Management and Information Center, University of
Georgia. This facility distributes computer programs developed by U.S.
government-funded projects.
Cross polarized
Describes a radar pulse in which the polarization direction of the return
is normal to the polarization direction of the transmission. Cross-
polarized images may be HV (horizontal transmit, vertical return) or VH
(vertical transmit, horizontal return).
Cross track scanner
Scanner in which a faceted mirror rotates about a horizontal axis to
sweep the detector IFOV in a series of parallel scan lines oriented
normal to the flight direction.
CRT
Cathode ray tube.
Cubic convolution
A high order resampling technique in which the brightness value of a
pixel in a corrected image is interpolated from the brightness values of
the 16 nearest pixels around the location of the corrected pixel.
Cut off
The digital number in the histogram of a digital image, which is set to
zero during contrast stretching. Usually this is a value below which
atmospheric scattering makes a major contribution.
CWA
Clean Water Act
Cycle
One complete oscillation of a wave.
CZCS
Coastal Zone color scanner.
D
Dangling ARC
An arc having the same polygon on both its left and right sides and
having at least one node that does not connect to any other arc. See
dangling node.
Dangling node
The dangling endpoint of a dangling arc. Often identifies that a polygon
does not close properly, that arcs do not connect properly, or that an
arc was digitized past its intersection with another arc. In many cases, a
dangling node may be acceptable. For example, in a street centerline
map, cul-de-sacs are often represented by dangling arcs.
Data collection system
On Landsats 1 and 2, the system that acquired information from
(DCS)
seismometers, flood gauges, and other measuring devices. These data
were relayed to ground receiving stations.
Glossary-6
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