Figure 15: Gain Feature For External Optic Adjustment - Teledyne FLIR A68 Series User Manual

Data Analysis: Gain Correction
Perform a linear regression on these mean DN values to find the slope [DN/°C]. The
line of best fit is described by the equation Y (DN) = bX (Temperature) + a, where b is
the slope of the line and a is the intercept (that is, the value of Y when X = 0). The
gain to apply is simply 100 over the computed slope (100/b). This provides a nominal
response of 100 DN per °C.
For example, if using 4 blackbodies with the following Temperature, DN (X,Y) values:
X
(Blackbody Temperature
35
37
40
45
The calculation summary is:
Sum of X= 157
Sum of Y= 134219
Mean X= 39.25
Mean Y= 33554.75
Sum of squares (SS
Sum of products (SP) = 4486.25
Regression Equation = ŷ =bX+a
b=SP/SS = 4486.25/56.75 = 79.05286
X
a= M -bM = 33554.75 - (79.05*39.25) = 30451.92511
Y X
ŷ = 79.05286X+ 30451.92511
Therefore, the gain to apply is 100 / b = (100/79.05) = 1.265.
Enter this gain value in the camera Radiometry Gain Correction feature, available in
the Contrast / Brightness/ Radiometry
FLIR A68/A38 Series IR Camera User's Manual
Y
°C (DN)
)
33224
33361
33629
34005
) = 56.75
X

Figure 15: Gain feature for external optic adjustment.

category.
Features and Configuration Options • 53