IDS Software Suite 4.96.1
The uEye driver provides various options to automatically adjust the image capture parameters to the lighting situation. These include:
•Auto exposure shutter (AES)
•Auto gain control (AGC)
•Auto white balance (AWB)
•Auto frame rate (AFR)
The auto functions are used to adjust the average brightness and color rendering of the camera image to their setpoint values, while trying to keep the frame rate at the highest possible value.
All controls are configured using the is_SetAutoParameter() and is_AutoParameter() SDK functions.
The control of the average brightness is preferably achieved by adjusting the exposure, i.e. you set the highest possible exposure time before gain is controlled. The auto exposure feature always uses the current exposure range which results from the selected pixel clock frequency and the frame rate. You can set separate control range limits for exposure and gain.
At the uEye models UI-122x/UI-322x/UI-522x the sensor can optionally control the exposure time.
The auto gain feature controls the camera master gain in a range from 0-100 %. You can set separate control range limits for exposure and gain.
Auto frame rate (AFR)
With the exposure control function enabled, you can still change the frame rate manually or automatically to maintain a dynamic exposure control range. A lower frame rate allows for longer exposure times, but then the live image display may exhibit jitter. The objective of the automatic frame rate control is to set the frame rate to an optimum value. This way, in all situations, the automatic exposure control can use the required control range at the highest possible frame rate.
Depending on the lighting source, light can have different color temperatures so that the images may have a color cast. At low color temperatures (e.g. light from incandescent lamps), the white content is offset towards a red hue. At high color temperatures (e.g. light from fluorescent lamps), the white content is offset towards a blue hue.
The white balance control feature uses the RGB gain settings of the camera to correct the white level. This is achieved by adjusting the gain controls within the 0-100 % range until the red or blue channel matches the average brightness of the green channel. In order to manually influence the color rendering, you can adjust the setpoint values for the red and blue channels relative to the green channel by using an offset value (see also uEye Cockpit: Histogram).
Automatically disabling the control function
You can disable the control functionality automatically once the target value has been reached (approximately) and after 3 regulations no improvement has been reached (API parameters IS_SET_AUTO_WB_ONCE and IS_SET_AUTO_BRIGHTNESS_ONCE). An event/a message notifies the system of this (see also is_Event()). Alternatively, you can keep the control feature enabled so that it responds to deviations from the target value.
You can set the auto function speeds in a 0 – 100 % range. This influences the control increments. High speed (100 %) causes a little attenuation of a fast-responding control and vice versa. The control functions for average brightness and for color rendering use separate speeds.
In trigger mode, every frame is evaluated for automatic control. The freerun mode skips a number of frames by default because in that mode, changes to the image parameters only become effective after one or more image captures (see also Applying new parameters). With the "Skip Frames" parameter (API parameter IS_SET_AUTO_SKIPFRAMES), you can select how many frames should be skipped in freerun mode (default: 4). This parameter strongly influences the control speed. Choosing small values can destabilize the automatic control.
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For higher frame rates select for the "Skip frames" parameter a bigger value. This reduces the number of automatic adjustments that must be done by the camera. |
The automatic control feature uses a hysteresis function for stabilization. Automatic control is stopped when the actual value lies in a range between (setpoint - hysteresis value) and (setpoint + hysteresis value). It is resumed when the actual value drops below (setpoint - hysteresis value) or exceeds (setpoint + hysteresis value). If the hysteresis value is increased, the control function will stop sooner. This can be useful in some situations.
