opto engineering ITALA - OE Auto Functions Control; OE Autoexposure;Autogain

Itala | INSTRUCTION MANUAL
6.5 OE Auto Functions Control
This sections includes all the features related to auto exposure and auto gain control.
Feature Description Interface Access
oeAutoTargetBrightness Desired brightness level (in %) of
the image used by auto gain and
auto exposure functions
IInteger RW
oeResultingBrightness Actual brightness level (in %) of
the image
IInteger R
oeAutoDampingFactor Control value (in %) used by auto
gain and auto exposure features
to reduce algorithm oscillations
IInteger RW
oeAutoConfidence Hysteresis around the target
value used by auto gain and auto
exposure features. Larger values
improve image stability but
increase the brightness error
IInteger RW
oeAutoAOIWidth Width of the area used for auto
functions calculations (in pixels)
IInteger RW
oeAutoAOIHeight Height of the area used for auto
functions calculations (in pixels)
IInteger RW
oeAutoAOIOffsetX Horizontal offset from the origin
to the area used for auto
functions calculations (in pixels)
IInteger RW
oeAutoAOIOffsetY Vertical offset from the origin to
the area used for auto functions
calculations (in pixels)
IInteger RW
Table 18: OE Auto Functions Control Features
6.5.1 OE Autoexposure/Autogain
When the correct amount of exposure time needed to have a sufficient level of brightness is not
known a priori, or when the illumination of the target changes during time, the autoexposure and
autogain features can be used to obtain a stable brightness level even if the external light condi-
tions are not constant.
For example, consider Fig.55: at the beginning of the acquisition (i.e. the first capture), the resulting
average grey level value of the image is equal to 50. Usually, a good exposure is centered at half of
the full scale range (about 127 in case of 8-bit image), so an average grey level value of 50% of the
full dynamic can be set in the oeAutoTargetBrightness feature. Thus, as it can be seen in Fig.55,
the average grey level value automatically adjusts in order to achieve the desired brightness of 127.
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