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Contents
Falcon4 86M Cameras
7.
Illuminate the sensor to 65% saturation for monochrome cameras. For color cameras, try to
adjust the light level equally above and below 55% for the most and least responsive color.
Ensure a high quality white reference is used.
8.
Set the Flat Field Calibration Algorithm to PRNU: Customer Target.
9.
Set
flat field target
to 80 % saturation (monochrome only). For color cameras, set the flat
field target to 1.2x the average of the highest responding color. See
flatfieldCalibrationTarget.
10.
Run
Gain (PRNU) calibration
. See
flatfieldCalibrationPRNU.
A defective 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.
More information is found in Appendix D.
Defective Pixel Detection and Replacement
The camera has three methods of replacing pixels. Single pixel replacement uses the FFC
coefficients to mark pixels that will be replaced. Defective columns or rows marked as defective use
the median filter algorithm to replace the defect pixel. The dynamic pixel replacement algorithm
uses a median filter to replace a given pixel value with the median value when its original value is
above / below a threshold when compared to adjacent pixels of the same color. These three
methods can be individually controlled.
Single Pixel Replacement
This is a technique for the elimination of dead or hot pixels.
The camera uses the FFC coefficients to indicate which pixels need to be replaced. If a pixel has a
Gain (PRNU) coefficient that is greater than the
defectivePixelReplacementGainThreshold
then the
pixel will be marked for replacement. Additionally, a pixel will be replaced if its Base Offset (FPN)
coefficient that is greater than the offset pixel replacement threshold
(
defectivePixelReplacementOffsetThreshold
). Lowering these thresholds will remove more pixels
with high gain and offset coefficients.
Most hot and dead pixels will be identified when a FPN or PRNU calibration is performed in camera.
The user can also manually mark a pixel for replacement by setting its Pixel Base Offset to 511.
The replacement algorithm is shown below in the Median Filter section.
Defective Columns and Row Replacement
Defective rows and columns are marked during factory calibration but users can add or remove
defective rows and columns to / from the list. The Pixel Replacement Mode can be set to Off, which
does not replace the defective rows and columns, or Active to hide defective rows and columns. To
clear all rows and columns from the list, use the Pixel Replacement Clear function. To add a
defective Row or Column the following steps are used:
1)
Select Row or Column using the Pixel Row or Column Selector.
2)
Set the Row or Column Id using the Pixel Replacement Row or Column Number field.
3)
The modified list can be saved in a user set.
