699-416
SUB-APPENDIX F12 - WAC FM NONLINEAR RESPONSE TERMS
The correction factors tabulated below correct for nonlinearity by
DN' = DN*C
| where |
C is the correction factor, |
| DN is the observed DN (after dark-count and bias subtraction), and |
| DN' is the desired DN. |
A correction algorithm can interpolate to get C as a function of observed DN for each pixel. This procedure should occur after the uneven bit weighting correction during the radiometric correction of each image. Note that DN' values greater than 4095 will result in some cases even though the data were not actually saturated. This fact will have an effect on the design of the radiometric correction software.
Correction factors for the four gain states are listed in the following table.
|
Gain 0
|
|
Gain 1
|
|
Gain 2
|
|
Gain 3
|
|
DN
|
C
|
DN
|
C
|
DN
|
C
|
DN
|
C
|
|
55.3
|
0.885
|
30.3
|
0.839
|
21.8
|
0.915
|
47.2
|
0.895
|
|
153.5
|
0.957
|
182.4
|
0.977
|
121.2
|
0.985
|
131.4
|
0.965
|
|
250.7
|
0.976
|
257.6
|
0.988
|
240.3
|
0.994
|
256.5
|
0.989
|
|
300.5
|
0.977
|
359.6
|
0.991
|
320.1
|
0.995
|
340.8
|
0.992
|
|
694.9
|
0.986
|
765.0
|
0.998
|
598.8
|
0.997
|
760.7
|
1.000
|
|
1167.7
|
1.006
|
1118.5
|
1.001
|
1034.9
|
1.000
|
1012.1
|
1.002
|
|
1472.7
|
0.997
|
1619.2
|
1.006
|
1509.9
|
1.002
|
1514.2
|
1.005
|
|
1805.8
|
0.976
|
1917.9
|
1.009
|
1827.8
|
1.002
|
1848.6
|
1.006
|
|
2430.6
|
1.047
|
2312.8
|
1.012
|
2219.6
|
1.004
|
2183.0
|
1.007
|
|
2844.5
|
1.101
|
2803.6
|
1.017
|
2687.7
|
1.007
|
2681.0
|
1.009
|
|
3405.9
|
1.092
|
3384.3
|
1.023
|
3231.7
|
1.010
|
3177.4
|
1.011
|
|
4095.0
|
1.168
|
4095.0
|
1.029
|
3902.4
|
1.020
|
3830.6
|
1.015
|
|
|
|
|
4095.0
|
1.020
|
4095.0
|
1.016
|
