The Piranha XL XDR Camera
•
29
Achieving the Best Image Stability
See the section Flat Field Category in Appendix A for GenICam features associated with this section
and how to use them
Relevant Features: Calibrate Black Level, Auto Black Enable
The camera design has been optimized to ensure that the image remains stable over a wide range
of temperatures. For applications that require even better image consistency over temperature, a
Calibrate Black Level feature is available. This function can be performed at any time, even when
imaging a bright field, with illumination ON. A lens cap (dark field) is not required.
The user can take advantage of this feature during non-imaging times of the inspection process.
For example, each time an inspected item or material is unloaded and a new item or material is
loaded, ready for inspection. When a Calibrate Black Level is initiated, the camera requires two
seconds to complete the operation.
If the inspection process has no non-imaging events over a long duration and the environment
experiences large changes in temperature, an automatic black balancing calibration feature is
available. When enabled, the camera automatically looks for opportunities to perform a black level
balance calibration where image content is uniform. However, image uniformity may be slightly
compromised where the image content has continuous rapid changes in contrast. For this algorithm
to be most effective, a User FPN and PRNU calibration should be performed, saved, and then
restored as appropriate to the current inspection environment.
When the camera powers up, it will default to the Auto Black Calibration ON mode, as this will be
backwards compatible with the operation of earlier cameras.
Adjusting Flat Field or Dark Calibration by Region*
See the section Flat Field Category in Appendix A for GenICam features associated with this section
and how to use them
Relevant features that adjust gain by region: ROI PRNU Multiplier, Multiply pixel PRNU coefficients
in ROI, User PRNU Set Selector, Save User PRNU Set, Load User PRNU Set
Relevant Features that adjust dark level by region: SFR ROI Selector, SFR ROI Offset X, SFR ROI
Width, SFR ROI Value
Some applications have bright and dark regions where a more even response is required. This can
be achieved by adjusting the gain for each region, adjusting the dark offset, or a combination of
the two.
Adjusting the gain will preserve relative contrast ratio. Adjusting the offset lower, which can include
below zero, with gain or to bring the image out of saturation can be used to enhance relative
contrast ratio.
Further, applications may also have several different lighting conditions with each requiring their
own flat field coefficients and the means to quickly and easily switch between them. To this end,
the following features are provided:
1.
The ability to apply a multiplier on up to four regions of user Flat Field (PRNU) coefficients.
2.
The ability to save and load user PRNU coefficients independent of a user set that contains
all adjustable parameters.
3.
The ability to adjust up to four regions of dark offset lower.
