User`s manual

56 Spyder3 S3-14 and S3-24 User's Manual
03-032-20117-00 Teledyne DALSA
PRNU Correction
Performs PRNU calibration to user entered value and eliminates the difference in responsivity between the most and
least sensitive pixel, creating a uniform response to light. Using this command, you must provide a calibration target.
Executing these algorithms causes the ssb command to be set to 0 (no background subtraction) and the
ssg command to 4096 (unity digital gain). The pixel coefficients are disabled (epc 0 0) during the
algorithm execution but returned to the state they were in prior to command execution.
Camera Link Command
Parameter
Description
Notes
cpa i i
i:
PRNU calibration algorithm to use:
1 = This algorithm first adjusts each tap’s analog gain so that 8-
13% of pixels within a tap are above the value specified in the
target value parameter. PRNU calibration then occurs using the
peak pixel in the region of interest.
This algorithm is recommended for use 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.
2 = Calculates the PRNU coefficients using the entered 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. 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.
3 = This algorithm includes an analog gain adjustment prior to
PRNU calibration. Analog gain is first adjusted so that the peak
pixel value in the tap ’s ROI is w ithin 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 useful for achieving uniform output across
multiple cameras by first adjusting analog gain and then
performing PRNU calibration. This algorithm is recommended for
use 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.
 Perform all analog
adjustments before
calibrating PRNU.
 This command
performs the same
function as the cpp
command but forces
you to 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.