Photon Focus MV8-D8424-G01-GT, User Manual, Page: 70 / 139

11 Pixel Data Processing
11.2 Column Group Correction
Due to the readout structure of the image sensors there are non uniformities in an image. The
Column Group Correction corrects dark signal non uniformities (DSNU) as well as Pixel response
non uniformities (PRNU) column wise. The correction parameters are obtained by a calibration
process. The calculation of the correction parameters is done in the Photonfocus production
facility.
11.2.1 Enable / Disable the Column FPN Correction
The Column Group Correction can be enabled or disabled with the property
colGroupCorrStatus
(in category
Photonfocus
/
colGroupCorrection
). By default, the correction is enabled.
11.2.2 Calibration of the Column FPN Correction
The Column FPN Correction of the camera is correctly calibrated at the Photonfocus production
facility. There is currently no possibility to recalibrate the camera after production.
11.3 Bad Pixel Correction
The Bad Pixel Correction corrects single pixel defects of the image sensor. If a pixel is marked as
"bad" (defect) then its value is replaced by the mean of the two neighbouring pixels on the
same image row.
11.3.1 Enable / Disable the Bad Pixel Correction
The Bad Pixel Correction can be enabled or disabled with the property
BadPixelCorrection_Enable
(in category
Correction
/
BadPixelCorrection
). By default the correction
is enabled.
11.3.2 Calibration of the Bad Pixel Correction
The calibration of the Bad Pixel Correction is based on a grey reference image, which is taken
at uniform illumination to give an image with a mid grey level. The Bad Pixel Correction is
calibrated in the production of the camera. More defect pixels may appear due to normal
aging of the image sensor. It is possible to recalibrate the Bad Pixel Correction with the
following instructions:
1. Setup the camera to the mode where it will be usually used. (Exposure time, ...). The
width and height should be set to its maximal value.
If different exposure times will be used, calibrate the camera under the longest
exposure time.
2. Put the camera in free-running mode by setting the property TriggerMode to Off .
3. Start grabbing of the camera by clicking on the
Play
button.
4. Wait until the camera has achieved working temperature.
5. The image sensor must be uniformly illuminated to give an image with a mid grey level.
Check this before you proceed with the instructions.
6. Set the visibility of the Device Control window of the PF_GEVPlayer to
Expert
.
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