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ipa: ipu3: Return filtered value

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When the current exposure value is calculated, it is cached and used by
filterExposure(). Use private filteredExposure_ and pass currentExposure
as a parameter.

In order to limit the use of filteredExposure_, return the value from
filterExposure().

While at it, remove a stale comment.

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>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
This commit is contained in:
Jean-Michel Hautbois 2022-02-24 16:11:10 +01:00 • committed by Umang Jain
parent ed13310b1f
commit 046ca79086
2 changed files with 40 additions and 35 deletions
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50
src/ipa/ipu3/algorithms/agc.cpp
View file

@ -72,7 +72,7 @@ static constexpr double kRelativeLuminanceTarget = 0.16;
Agc::Agc()
: frameCount_(0), lineDuration_(0s), minShutterSpeed_(0s),
maxShutterSpeed_(0s), filteredExposure_(0s), currentExposure_(0s)
maxShutterSpeed_(0s), filteredExposure_(0s)
{
}
@ -143,33 +143,37 @@ double Agc::measureBrightness(const ipu3_uapi_stats_3a *stats,
/**
* \brief Apply a filter on the exposure value to limit the speed of changes
* \param[in] exposureValue The target exposure from the AGC algorithm
*
* The speed of the filter is adaptive, and will produce the target quicker
* during startup, or when the target exposure is within 20% of the most recent
* filter output.
*
* \return The filtered exposure
*/
void Agc::filterExposure()
utils::Duration Agc::filterExposure(utils::Duration exposureValue)
{
double speed = 0.2;
/* Adapt instantly if we are in startup phase */
/* Adapt instantly if we are in startup phase. */
if (frameCount_ < kNumStartupFrames)
speed = 1.0;
if (filteredExposure_ == 0s) {
/* DG stands for digital gain.*/
filteredExposure_ = currentExposure_;
} else {
/*
* If we are close to the desired result, go faster to avoid making
* multiple micro-adjustments.
* \todo Make this customisable?
*/
if (filteredExposure_ < 1.2 * currentExposure_ &&
filteredExposure_ > 0.8 * currentExposure_)
if (filteredExposure_ < 1.2 * exposureValue &&
filteredExposure_ > 0.8 * exposureValue)
speed = sqrt(speed);
filteredExposure_ = speed * currentExposure_ +
filteredExposure_ = speed * exposureValue +
filteredExposure_ * (1.0 - speed);
}
LOG(IPU3Agc, Debug) << "After filtering, total_exposure " << filteredExposure_;
LOG(IPU3Agc, Debug) << "After filtering, exposure " << filteredExposure_;
return filteredExposure_;
}
/**
@ -213,26 +217,28 @@ void Agc::computeExposure(IPAFrameContext &frameContext, double yGain,
* Calculate the current exposure value for the scene as the latest
* exposure value applied multiplied by the new estimated gain.
*/
currentExposure_ = effectiveExposureValue * evGain;
utils::Duration exposureValue = effectiveExposureValue * evGain;
/* Clamp the exposure value to the min and max authorized */
utils::Duration maxTotalExposure = maxShutterSpeed_ * maxAnalogueGain_;
currentExposure_ = std::min(currentExposure_, maxTotalExposure);
LOG(IPU3Agc, Debug) << "Target total exposure " << currentExposure_
exposureValue = std::min(exposureValue, maxTotalExposure);
LOG(IPU3Agc, Debug) << "Target total exposure " << exposureValue
<< ", maximum is " << maxTotalExposure;
/* \todo: estimate if we need to desaturate */
filterExposure();
/* Divide the exposure value as new exposure and gain values */
utils::Duration exposureValue = filteredExposure_;
utils::Duration shutterTime;
/*
* Filter the exposure.
* \todo: estimate if we need to desaturate
*/
exposureValue = filterExposure(exposureValue);
/*
* Divide the exposure value as new exposure and gain values.
*
* Push the shutter time up to the maximum first, and only then
* increase the gain.
*/
shutterTime = std::clamp<utils::Duration>(exposureValue / minAnalogueGain_,
utils::Duration shutterTime =
std::clamp<utils::Duration>(exposureValue / minAnalogueGain_,
minShutterSpeed_, maxShutterSpeed_);
double stepGain = std::clamp(exposureValue / shutterTime,
minAnalogueGain_, maxAnalogueGain_);

3
src/ipa/ipu3/algorithms/agc.h
View file

@ -33,7 +33,7 @@ public:
private:
double measureBrightness(const ipu3_uapi_stats_3a *stats,
const ipu3_uapi_grid_config &grid) const;
void filterExposure();
utils::Duration filterExposure(utils::Duration currentExposure);
void computeExposure(IPAFrameContext &frameContext, double yGain,
double iqMeanGain);
double estimateLuminance(IPAFrameContext &frameContext,
@ -51,7 +51,6 @@ private:
double maxAnalogueGain_;
utils::Duration filteredExposure_;
utils::Duration currentExposure_;
uint32_t stride_;
};