User`s manual

Piranha4 4K and 2K Dual Line Monochrome CMOS Camera User's Manual 47
Teledyne DALSA 03-032-20176-02
Figure 23: Camera Calibration Process.
Calibration
The goal of calibration is to produce a uniform, white balanced and, if required, color corrected image at
the desired level out of the camera when it is imaging a uniform white object, using the optical setup of
the user‘s application.
The user should configure the camera to use the EXSYNC and exposure timing they desire plus adjust the
light level for normal operation. The lens should be at the desired magnification, aperture and be in focus.
As the white reference located at the object plane will be in focus, any features on its surface (e.g. dust,
scratches) will end up in the calibration profile of the camera. To avoid this, use a clean white plastic or
ceramic material, not paper. Ideally, the white object should move during the calibration process as the
averaging process of the camera will diminish the effects on any small variation in the white reference.
The user may wish to start the calibration process by evaluating the characteristics of their setup with no
calibration enabled. This can be readily achieved by disabling FPN, PRNU & color correction coefficients,
setting white balance red, green and blue gains to one, and the system gain to one.
Begin by adjusting the system gain until the peak intensity of the three colors is at the desired DN level.
You may want to use the white balance gains to adjust the peak of each color to be a similar DN value,
but this is not necessary. Before proceeding any further, it is desirable to complete an FPN calibration.
This is best performed using a lens cap to ensure no light gets into the camera. Once complete, a PRNU
calibration can be performed using a target value you want all the pixels to achieve. This target value can
be higher or lower than the peak values you observed while initially setting up the camera. Once PRNU
calibration is complete, it will take several seconds, all three colors should be at the target value, white
balance gains will have been adjusted to suit the cameras optimum setup for a balanced white output,
and the correction coefficient will be enabled. The system gain will remain as originally set. The
coefficient and gain parameters, timing and control configuration etc can be stored in any one of eight
user sets and automatically retrieved at power up or by user selection. If a color correction matrix is
desired, the user can download and save a color correction file derived from the process described above.
Note: For the color correction to be effective, the camera should have a white balanced output when color
correction is off.
CamExpert has a default timeout of 20 seconds per command, which is too short for the FFC
calibration to run fully. You can change the default timeout by setting a command line argument in
the short-cut:
 Right click on the short-cut in the start menu and select properties.
 Add –timeout 60 to increase the command timeout to 60 seconds (See below). Note that you
must include a character space between the closing quotation mark in the target and the
hyphen before the timeout value.
 Repeat for desktop short-cut
Video
Gain
Output
Video
Digital Processing
(
monochrome
)
x
Gain
(
ssg
)
x
Calibrate
PRNU
flatfieldCorrectionMode
flatfieldCalibrationPRNU
flatfieldCorrectionAlgorithm
(
cpa
,
ffm
)
-
Calibrate FPN
flatfieldCalibrationFPN
(
ccf
)
Filter Threshold
ImageEnhancementStrength
(
sft
)
“Output
_
LUT”
-
+
Offset
BlackLevel
(
ssb
)