Contrast

contrast

In meteorological usage, contrast C is defined by

where L₀ is the luminance of a target object and L_s is that of its immediate visual surroundings.

Both luminances may include airlight or reflected glare, and L_s is always assumed to be greater than zero. Because detection outdoors often depends on luminance rather than chromaticity differences, C is usually calculated from spectrally integrated luminances. Contrast for a perfectly black target is -1 but, in principle, C has no upper limit for a self-luminous target. If

is less than a variable threshold contrast, the target is visually indistinguishable from its surroundings.

INDEX
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
0
1
2
3
4
5
6
7
8
9