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ipa: ipu3: agc: Refactor condition on exposure correction

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Simplify the reading by removing one level of indentation to return
early when the change is small between two calls.

Reword the LOG() message when we are correctly exposed, and move the
lastFrame_ variable to update it even if the change is small.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
This commit is contained in:
Jean-Michel Hautbois 2021-10-12 20:38:10 +02:00
parent cd0b3402ea
commit cbf2c9a612
1 changed files with 55 additions and 52 deletions
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107
src/ipa/ipu3/algorithms/agc.cpp
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@ -138,61 +138,64 @@ void Agc::lockExposureGain(uint32_t &exposure, double &analogueGain)
if ((frameCount_ < kInitialFrameMinAECount) || (frameCount_ - lastFrame_ < kFrameSkipCount))
return;
lastFrame_ = frameCount_;
/* Are we correctly exposed ? */
if (std::abs(iqMean_ - kEvGainTarget * knumHistogramBins) <= 1) {
LOG(IPU3Agc, Debug) << "!!! Good exposure with iqMean = " << iqMean_;
} else {
double evGain = kEvGainTarget * knumHistogramBins / iqMean_;
/* extracted from Rpi::Agc::computeTargetExposure */
utils::Duration currentShutter = exposure * lineDuration_;
currentExposureNoDg_ = currentShutter * analogueGain;
LOG(IPU3Agc, Debug) << "Actual total exposure " << currentExposureNoDg_
<< " Shutter speed " << currentShutter
<< " Gain " << analogueGain
<< " Needed ev gain " << evGain;
currentExposure_ = prevExposureValue_ * evGain;
utils::Duration minShutterSpeed = minExposureLines_ * lineDuration_;
utils::Duration maxShutterSpeed = maxExposureLines_ * lineDuration_;
utils::Duration maxTotalExposure = maxShutterSpeed * kMaxGain;
currentExposure_ = std::min(currentExposure_, maxTotalExposure);
LOG(IPU3Agc, Debug) << "Target total exposure " << currentExposure_
<< ", maximum is " << maxTotalExposure;
/* \todo: estimate if we need to desaturate */
filterExposure();
utils::Duration exposureValue = filteredExposure_;
utils::Duration shutterTime = minShutterSpeed;
/*
* Push the shutter time up to the maximum first, and only then
* increase the gain.
*/
shutterTime = std::clamp<utils::Duration>(exposureValue / kMinGain,
minShutterSpeed, maxShutterSpeed);
double stepGain = std::clamp(exposureValue / shutterTime,
kMinGain, kMaxGain);
LOG(IPU3Agc, Debug) << "Divided up shutter and gain are "
<< shutterTime << " and "
<< stepGain;
exposure = shutterTime / lineDuration_;
analogueGain = stepGain;
/*
* Update the exposure value for the next process call.
*
* \todo Obtain the values of the exposure time and analog gain
* that were actually used by the sensor, either from embedded
* data when available, or from the delayed controls
* infrastructure in case a slow down caused a mismatch.
*/
prevExposureValue_ = shutterTime * analogueGain;
LOG(IPU3Agc, Debug) << "We are well exposed (iqMean = "
<< iqMean_ << ")";
return;
}
lastFrame_ = frameCount_;
double evGain = kEvGainTarget * knumHistogramBins / iqMean_;
/* extracted from Rpi::Agc::computeTargetExposure */
utils::Duration currentShutter = exposure * lineDuration_;
currentExposureNoDg_ = currentShutter * analogueGain;
LOG(IPU3Agc, Debug) << "Actual total exposure " << currentExposureNoDg_
<< " Shutter speed " << currentShutter
<< " Gain " << analogueGain
<< " Needed ev gain " << evGain;
currentExposure_ = prevExposureValue_ * evGain;
utils::Duration minShutterSpeed = minExposureLines_ * lineDuration_;
utils::Duration maxShutterSpeed = maxExposureLines_ * lineDuration_;
utils::Duration maxTotalExposure = maxShutterSpeed * kMaxGain;
currentExposure_ = std::min(currentExposure_, maxTotalExposure);
LOG(IPU3Agc, Debug) << "Target total exposure " << currentExposure_
<< ", maximum is " << maxTotalExposure;
/* \todo: estimate if we need to desaturate */
filterExposure();
utils::Duration exposureValue = filteredExposure_;
utils::Duration shutterTime = minShutterSpeed;
/*
* Push the shutter time up to the maximum first, and only then
* increase the gain.
*/
shutterTime = std::clamp<utils::Duration>(exposureValue / kMinGain,
minShutterSpeed, maxShutterSpeed);
double stepGain = std::clamp(exposureValue / shutterTime,
kMinGain, kMaxGain);
LOG(IPU3Agc, Debug) << "Divided up shutter and gain are "
<< shutterTime << " and "
<< stepGain;
exposure = shutterTime / lineDuration_;
analogueGain = stepGain;
/*
* Update the exposure value for the next process call.
*
* \todo Obtain the values of the exposure time and analog gain
* that were actually used by the sensor, either from embedded
* data when available, or from the delayed controls
* infrastructure in case a slow down caused a mismatch.
*/
prevExposureValue_ = shutterTime * analogueGain;
}
void Agc::process(IPAContext &context, const ipu3_uapi_stats_3a *stats)