Dalsa C1240, User Manual, Page: 137 / 327

Nano Series GigE Vision Camera Operational Reference • 127
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Enable all Auto-Brightness features by setting autoBrightnessMode to active (live acquisition
must be off). This master feature only activates the auto-brightness, auto-exposure, and
auto-gain controls but doesn’t enable the processing.
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The features autoBrightnessSequence, autoBrightnessTargetSource, autoBrightnessTarget,
autoBrightnessTargetRangeVariation, and autoBrightnessAlgorithm can remain at their
default settings for this demo.
• Note that the Auto-Brightness function is not available if “Cycling Mode” is active.
The Auto-Brightness examples below are summarized as follows:
• Auto-Brightness by Frame Luminance Averaging
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Auto-Brightness by Adjusting a Digital Gain
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Auto-Brightness by Adjusting both Gain and Exposure
Auto-Brightness with Frame Luminance Averaging
After the preparations described above, the Auto-Exposure function is tested as follows. These
setup steps are made before doing a live acquisition.
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Set the autoBrightnessAlgoConvergenceTime to a larger value than the default 2 seconds if
more time is required to ensure adequate time for convergence.
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Set ExposureAuto to Continuous to activate all Auto-exposure features.
• Referring to the ExposureTime value used to get a viewable image during the free-running
preparation stage, set exposureAutoMaxValue to a maximum exposure time longer than
was needed. This maximum exposure limit feature may be required in imaging situations
where the frame rate must not be forced below some minimum value. Also check that
exposureAutoMinValue is low enough to allow the auto exposure a wide range to function in
(but not too low else the algorithm will undershoot).
• Enable live acquisition (Grab button in CamExpert). The image exposure will adjust itself
until the autoBrightnessTarget value is achieved. During live acquisition, the
autoBrightnessTarget value can be changed to observe the algorithm converge to the new
luminance value.
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Stop live acquisition (Freeze button in CamExpert). The feature ExposureTime is updated
with the last exposure time used by the auto exposure algorithm. Adjust frame rate and
analog gain settings as required to test again. Adjust other features mentioned as required.
Auto-Gain
An alternative method of automating exposure control is by varying the Nano Digital Gain. The user
needs to note that the digital gain stage is limited to a small positive multiplier and will have the
side effect of increasing digital noise.
• Setup will be similar to using auto exposure alone.
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Enable automatic digital gain by setting the feature GainAuto to Continuous.
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Limit the total digital gain range by adjusting the values for gainAutoMaxValue and
gainAutoMinValue.
Auto-Brightness by using Auto-Exposure and Auto-Gain
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Use both ExposureAuto and GainAuto together to maximize the range of the Auto-
Brightness range.
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Use autoBrightnessSequence to select the order of automation.
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Caution: Even with both automatic functions enabled, exposure convergence to a target
value requires proper setup.