Piranha Color Camera User’s Manual
46
DALSA
03-032-10211-01
5/9/2007
value as shown below:
PRNU
Coefficient
=
Target
(AVG
Pixel
Value
)
‐
(FPN
+
value)
sdo
i
i
i
The calculation is performed for all sensor pixels but warnings
are only applied to pixels in the region of interest. This
algorithm is useful for achieving uniform output across
multiple cameras. It is important that the target value (set with
the next parameter) is set to be at least equal to the highest
pixel across all cameras so that all pixels can reach the highest
pixel value during calibration. Confirm this using the
gla
statistics.
3
= This algorithm includes an analog gain adjustment prior to
PRNU calibration. Analog gain is first adjusted so that the peak
pixel value in tap’s ROI is within 97 to 99% of the specified
target value. It then calculates the PRNU coefficients using the
target value as shown below:
PRNU
Coefficient
=
Target
(AVG
Pixel
Value
)
‐
(FPN
+
value)
sdo
i
i
i
The calculation is performed for all sensor pixels but warnings
are only applied to pixels in the region of interest. This
algorithm is useful for achieving uniform output across
multiple cameras.
This algorithm is should be used only when FPN is negligible
and FPN coefficients are set to zero. Since this algorithm
adjusts the analog gain, it also affects FPN. If FPN is calibrated
prior to running this algorithm, FPN will be observable in dark
conditions and an incorrect FPN value will be used during
PRNU calibration resulting in incorrect PRNU coefficients.
This algorithm is more robust and repeatable than algorithm 1
because it uses an average pixel value rather than a number
above target. However, this algorithm is slower.
4
= Calculates the PRNU coefficient in the same way as
cpa 2
with the exception that this command only calculates PRNU
for pixels within the current Region of Interest (ROI).
i
2
Peak target value in a range from 1024 to 4055DN. The target
value must be greater than the current peak output value.
Notes:
•
Perform all analog adjustments before calibrating PRNU.
•
This command performs the same function as the
cpp
command with the exception that you enter a target value.
•
Calibrate FPN before calibrating PRNU. If you are not
performing FPN calibration then issue the
rpc
(reset pixel
coefficients) command and set the
sdo
(set digital offset)
value so that the output is near zero under dark.
Example:
cpa 1 600
Performing PRNU Calculation to a Camera Calculated Value
Purpose:
Performs PRNU correction and eliminates the difference in
responsivity between the most and least sensitive pixel creating a
uniform response to light.
Syntax
ccp
Summary of Contents for PC-30-02K60
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