5
3
1
2
Figure 4 : Dark field calibration steps
3.2
Flat field calibration process
The choice of which light intensity to use for the bright field calibration requires a little bit more
thought. If you perform the calibration with a light intensity too close to camera saturation you might
compensate the camera too much and actually introduce more PRNU for low light intensities. If you
use a weak light intensity, the differences in photo response might be too small and you under-
compensate the sensor. In general a light intensity that gives a signal somewhere around 40% of the
sensor full scale should give the optimal result.
Follow this steps to perform flat field calibration process:
1.
Prepare light source. Uniform light should be applied across the sensor. This can be achieved by
removing the lens and setting a uniform light source, such as diffused light or integrating sphere,
in front of the camera
2.
Set the “Field Calibration Mode” to “Flat” (1)
3.
Start camera’s stream either in free run or by applying an external trigger
4.
Initiate the selected calibration with “Field Calibration Start” command Execute (2)
5.
Stop camera’s stream
6.
Enable the Flat filed correction (3)
7.
Start camera’s stream either in free run or by applying an external trigger
NOTE that Flat field calibration should be performed after Dark field calibration has already be
performed for the selected camera settings.
Using the DSNU and PRNU corrections
