Dalsa Piranha XL PX-HM-16K12B-00-R, Руководство пользователя

Страница: 29 / 66

The Piranha XL Camera
•
27
Setting Custom PRNU Coefficients
There may also be circumstances when the user wants to upload their own PRNU coefficients. PRNU
coefficients can be custom modified and uploaded to the camera. They can also be downloaded
from the camera.
To download and upload PRNU coefficients, use File Access Control Category > Upload / Download
File > Settings and select Miscellaneous > Current PRNU to download / upload a file. The file format
is described in 03-084-20123 Piranha XL Binary File Format which can be obtained from Teledyne
DALSA Technical Support. This document also includes Excel spread sheet examples.
Once the PRNU coefficients are uploaded, they are used immediately by the camera. To avoid loss
at power up or changing row settings, they should be saved in one of the 8 available user sets.
Flat Field Calibration Filter
See the section Flat Field Category in Appendix A for GenICam features associated with this section
and how to use them
Relevant Features: Calibration Algorithm
If a sheet of material is being used as a white target, it must be completely free of blemishes and
texture. Any dirt or texture present will generate a variation in the image that will be incorporated
into the calibration coefficients of the camera. Once the target is removed, or moved, vertical
stripes will be present in the scanned image. Dirt or texture that has dark characteristics will
appear as bright vertical lines. And dirt or texture that has bright characteristics will appear as dark
vertical lines. One way to minimize this affect is for the white target to be moving during the
calibration process. This has the affect of averaging out any dirt or texture present. If this is not
possible, the camera has a feature where a flat field calibration filter can be enabled when
generating the flat field correction coefficients which can minimize the effects of dirt. Note that this
filter is only capable of compensating for small, occasional contaminants.
Flat Field Calibration Region of Interest
See the section Flat Field Category in Appendix A for GenICam features associated with this section
and how to use them
Relevant Features: ROI Offset X, ROI Width
There are occasions when the camera’s field of view includes areas that are beyond the material to
be inspected. This may occur for cameras imaging off the edge of a panel or web. Another type of
inspection system may be imaging multiple lanes of material. The edge of the material or between
lanes may not be illuminated in the same way as the areas of inspection and, therefore, would
cause problems with a flat field calibration. The camera can accommodate these “no inspection
zones” by defining up to four Regions of Interest (ROI) where flat field calibration is performed.
Image data outside the ROI is ignored by the flat field calibration algorithm. Each ROI is user
selected with the pixel boundaries defined by the pixel start address and pixel width and then
followed by initiating flat field calibration for that region. Once completed, the next ROI can be
defined and flat field calibrated.