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Reference Manual ATOM one SSM500
16 Auto Exposure
16.1 aec <enable> <setPoint> <speed> <clmTolerance> <costGain>
<costTint> <costApt> <taf> <maxGain> <useCustomWeights>
Configures auto exposure control.
The auto exposure is fully controllable by the user. Depending of the application the user
can decide how the exposure control should work.
The target luminance is set by the setPoint, this will determine how bright the image looks.
A higher setPoint results in a brighter exposed image.
By default the auto exposure does not use the full available gain range. Use the maxGain
parameter to change the maximum sensor gain which is used by the algorithm. Please
note, that high maximum gain values can make the auto exposure control unstable.
If the lighting conditions allow it, the exposure control will avoid flicker effects caused by
artificial (indoor) lights by only using shutter times which are multiples of a given flicker
frequency taf. For countries with power frequencies of 50 Hz (e.g. Europe) you should use
a taf value of 10000 µs, in countries with a 60 Hz power frequency (e.g. USA), use a value
of 8333 µs.
The speed determines how fast the exposure control reacts to luminescence changes. A
higher value means a slow reaction to changes.
The sensitivity determines how big a luminescence change has to be before the auto
exposure control reacts to it. A higher value means a bigger change in luminescence is
needed.
By settings a “cost” factors for gain, exposure or aperture the user can set priorities how
the exposure should work. The parameter with the lowest costs is most preferred by the
auto exposure control, the parameter with the highest costs will be kept as low as possible.
Setting a cost factor to 0 will remote this parameter out of the automatic loop. The user
must set this factor to fixed value. Check the examples below to get an idea how it works.
Aperture control (auto iris) is only available on some OEM devices, or if an external lens
drive unit is attached (see chapter 18). To enable it set costApt to a non-zero value.
To use a customized aec algorithm set the “useCustomWeights” flag. For more information
on how to setup the custom weighting, see chapter 16.2.
Function call:
aec <enable> <setPoint> <speed> <clmTolerance> <costGain>
<costTint> <costApt> <taf> <maxGain> <useCustomWeights>
Parameter
Description
Remarks
enable
0: disable, 1: enable aec
setPoint
Target luminance
Range 256...3000, Default 1000
speed
Control speed
Range 3…30, Default: 10
