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Falcon 4 Camera User's Manual
Camera Operation
If the calibration finds any defective pixels, where its FPN base value is greater than Pixel
Replacement Offset Threshold, or its PRNU value is greater than Pxiel Replacement Gain Threshold,
the pixel can be replaced if Pixel Replacement Mode is Active.
The gain (PRNU) calibration is performed next to determine the multiplication factors required to
bring each pixel to the required value (target) for flat, white output. For the monochrome cameras,
the target is determined by the user (See flatfieldCalibrationTarget).
It is important to do the FPN correction first. Results of the FPN correction are used in the PRNU
procedure.
Let’s go through a flat field calibration example:
1.
The camera is placed in internal exposure and frame rate. Ensure that the area of
interest (AOI) is set to the full window (i.e. Width=SensorWidth and Height=SensorHeight).
No other exposure mode or AOI configuration will allow FFC calibration. See ExposureMode,
TriggerMode, OffsetX, OffsetY, Width, Height.
2.
Settings such as frame rate, exposure time, etc. are set as close as possible to the actual
operating conditions. Set system gain[All Digital] to 1 and background subtract to 0,
as these are the defaults during FFC calibration. See GainSelector, Gain, BlackLevelSelector,
and BlackLevel.
3.
Select correction active set to user flat field x. Go to flat field correction mode, select
calibration. See flatfieldCorrectionCurrentActiveSet, and flatfieldCorrectionMode.
4.
Clear existing coefficients. See flatfieldCalibrationClearCoefficient.
5.
Place the camera in the dark (i.e. cover lens) and run FPN calibration. This performs the
FPN correction and saves the FPN coefficients to temporary memory. See
flatfieldCalibrationFPN.
6.
Calibration mode enables both FPN and PRNU correction. Verify signal output is close to 0
DN.
7.
Illuminate the sensor to 65 % saturation, using a high quality white reference.
8.
Set flat field target to 80 % saturation (monochrome only). See flatfieldCalibrationTarget.
9.
Select Gain Calibration Mode as either High Gain or High Resolution
10.
Run Gain (PRNU) calibration. See flatfieldCalibrationPRNU.
The defect pixel will be replaced if Pixel Replacement Mode is Active. A defective pixel is
defined as a pixel whose FPN base value is greater than Pixel Replacement Offset Threshold
or/and whose PRNU value is greater than Pixel Replacement Gain Threshold.
11.
Save the flat field calibration: flatfieldCalibrationSave.
Preliminary
