3.5
Dual
modes
Cameras based on the IMX530, IMX531, IMX532 sensors support Dual ADC readout modes. In these modes a single exposed frame can
be read out twice via different readout channels resulting in two images with different analog gain settings. The high gain (HG) image has
a lower readout noise and therefore offers better signal to noise ratio (SNR) in the low light regions of the scene. On the other hand, the
low gain (LG) image offers higher SNR in the well illuminated regions of the scene as it utilizes the larger (or the whole) portion of the full
well capacity.
Figure 57: Dual ADC non-combined without merging
These two images can be either read out separately from the sensor (Non-combined mode) and transported to the host PC memory or
combined in the sensor into a single HDR frame with a piecewise linear response. (Combined mode).
// Set dual ADC mode to non-combined or combined
xiSetParamInt(xiH, XI_PRM_DUAL_ADC_MODE,XI_DUAL_ADC_MODE_NON_COMBINED);
// or
xiSetParamInt(xiH, XI_PRM_DUAL_ADC_MODE, XI_DUAL_ADC_MODE_COMBINED);
The gain parameter is used to define the analog gain of the low gain channel (slope A) and the dual ADC gain ratio parameter is used to
adjust the offset/ratio of the analog gain of the high gain channel (slope B / slope A).
// Set gain selector to analog
xiSetParamInt(xiH, XI_PRM_GAIN_SELECTOR, XI_GAIN_SELECTOR_ANALOG_ALL);
// Set gain to arbitrary value
xiSetParamFloat(xiH, XI_PRM_GAIN, 0);
// Set gain ratio to arbitrary value
// depending on the gain value the range can be from 0--24 dB
// with 6 dB increment
xiSetParamFloat(xiH, XI_PRM_DUAL_ADC_GAIN_RATIO, 12);
XIMEA Technical Manual, Version: v230927
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