Allied Vision Goldeye CL Series, Техническое руководство

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Image data flow
223 Goldeye G/CL Technical Manual V4.2.0
Operating the automatic exposure control based on the Mean value
Set the
ExposureAutoAlg
feature to
Mean
, and set the
ExposureAutoTarget
feature to the desired value.
In this case the automatic exposure control loop is aimed at keeping the mean
value of the image histogram equal to the value set by
ExposureAutoTarget
.
The value for
ExposureAutoTarget
needs to be specified in percentage from the
full dynamic range, including the outliers’ areas. Higher values of
ExposureAutoTarget
will cause longer exposure times, thus result in brighter
images, lower values cause shorter exposure times, thus result in darker images.
If this value is set to 40 percent, then 40 percent of all pixels of the image are
darker and 60 percent of all pixels of the image are brighter than this value.
Operating the automatic exposure based on the full range of values
Set the
ExposureAutoAlg
feature to
FitRange
. The
ExposureAutoTarget
feature has no influence in this case.
In this case the automatic exposure control loop regulates the exposure in such a
way that the maximum value of the image histogram is kept close to the upper end
of the dynamic range of the camera.
Tolerance
If the automatic exposure is calculated for every frame (
ExposureAuto
=
Continuous
), most likely there are minuscule adjustments to be applied to each
frame. These adjustments may cause certain, though usually insignificant,
variations of the image brightness between consecutive frames.
To prevent these adjustments, the feature
ExposureAutoAdjustTol
can be used.
The exposure is adjusted only if the current regulated value deviates from the ideal
target value by more than a given percentage.
Slowing down the auto exposure adjustments
Usually, the automatic exposure adjustments run at full speed. Using the
ExposureAutoRate
feature, you can slow down the automatic exposure
adjustments to a fraction of the maximum possible speed. This can be useful for
some applications and sensor settings, to prevent the auto exposure control loop
from occurring oscillations.