Automatic Exposure And Gain Control - Smartek UCC User Manual

5.2.3 Automatic Exposure and Gain Control

Cameras are often used in different environments and applications with changing conditions, such as
scene illumination which may vary and change constantly. At certain aperture size, exposure time and gain
values, the image captured by the camera can be underexposed (too dark) or overexposed (too bright), thus
losing image details. As described in previous chapters the image brightness can be adjusted by changing
exposure time and gain values. The SMARTEK Vision twentynine camera series provides on-camera
automatic control of exposure time and gain, thus automatically adjusting the values within defined limits,
until the specified target image brightness is reached.
The operation of the automatic exposure and automatic gain algorithms can be controlled via the properties
ExposureAuto , adjusting the exposure, and GainAuto , adjusting the gain of the camera. Both have three
operation modes, listed in Table 23.
Value
Off
Once
Continuous
In case when both ExposureAuto and GainAuto are set to Continuous mode, the automatic control
algorithm always tries to achieve the smallest gain value to keep the noise level as low as possible.
Parameters that control Automatic Exposure and Automatic Gain features are listed in the following table:
Parameter
TargetGrayValue
ExposureTimeAbsLowerLimit
ExposureTimeAbsUpperLimit
GainAbsLowerLimit
GainAbsUpperLimit
For cameras that do not support on-camera automatic exposure and automatic gain control, the automatic
adjustment of the camera's exposure time and gain within user application can be realized by using the
ImageProcAPI provided by the CameraSuite SDK. For detailed description of the automatic exposure and
gain features in the SDK please refer to chapter 8.2.3 - Auto Exposure and Auto Gain .
Automatic mode is disabled; exposure and gain can be set manually via the
Automatic Exposure/Gain is done once until the target gray value is reached,
Automatic Exposure/Gain algorithm is running continuously
Table 23: ExposureAuto and GainAuto operation modes
Type
Integer
Float
Float
Float
Float
Table 24: Automatic functions parameters
Description
ExposureTime and Gain properties
the operation mode is then set to Off
The average image brightness that should be reached
The minimum exposure time (in
set by the Automatic Exposure algorithm
The maximum exposure time (in
set by the Automatic Exposure algorithm
The minimum gain value (in dB) that is allowed to be set
by the Automatic Gain algorithm
The maximum gain value (in dB) that is allowed to be set
by the Automatic Gain algorithm
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User Manual - twentynine
Description
s) that is allowed to be
µ
s) that is allowed to be
µ
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