[PATCH v2 8/8] ipa: rkisp1: Remove bespoke Agc functions
Paul Elder
paul.elder at ideasonboard.com
Fri Apr 19 04:54:26 CEST 2024
Hi Dan,
On Wed, Apr 17, 2024 at 02:15:36PM +0100, Daniel Scally wrote:
> Now that the rkisp1 Agc algorithm is a derivation of MeanLuminanceAgc
> we can remove the bespoke functions from the IPA's class.
>
> Reviewed-by: Stefan Klug <stefan.klug at ideasonboard.com>
> Signed-off-by: Daniel Scally <dan.scally at ideasonboard.com>
Looks good to me.
Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
> Changes in v2:
>
> - Kept the documentation for estimateLuminance()
>
> src/ipa/rkisp1/algorithms/agc.cpp | 231 ++----------------------------
> src/ipa/rkisp1/algorithms/agc.h | 9 --
> 2 files changed, 14 insertions(+), 226 deletions(-)
>
> diff --git a/src/ipa/rkisp1/algorithms/agc.cpp b/src/ipa/rkisp1/algorithms/agc.cpp
> index 0d66fcca..27b6f2c1 100644
> --- a/src/ipa/rkisp1/algorithms/agc.cpp
> +++ b/src/ipa/rkisp1/algorithms/agc.cpp
> @@ -36,30 +36,7 @@ namespace ipa::rkisp1::algorithms {
>
> LOG_DEFINE_CATEGORY(RkISP1Agc)
>
> -/* Minimum limit for analogue gain value */
> -static constexpr double kMinAnalogueGain = 1.0;
> -
> -/* \todo Honour the FrameDurationLimits control instead of hardcoding a limit */
> -static constexpr utils::Duration kMaxShutterSpeed = 60ms;
> -
> -/* Number of frames to wait before calculating stats on minimum exposure */
> -static constexpr uint32_t kNumStartupFrames = 10;
> -
> -/* Target value to reach for the top 2% of the histogram */
> -static constexpr double kEvGainTarget = 0.5;
> -
> -/*
> - * Relative luminance target.
> - *
> - * It's a number that's chosen so that, when the camera points at a grey
> - * target, the resulting image brightness is considered right.
> - *
> - * \todo Why is the value different between IPU3 and RkISP1 ?
> - */
> -static constexpr double kRelativeLuminanceTarget = 0.4;
> -
> Agc::Agc()
> - : frameCount_(0), filteredExposure_(0s)
> {
> supportsRaw_ = true;
> }
> @@ -117,12 +94,6 @@ int Agc::configure(IPAContext &context, const IPACameraSensorInfo &configInfo)
> context.configuration.agc.measureWindow.h_size = 3 * configInfo.outputSize.width / 4;
> context.configuration.agc.measureWindow.v_size = 3 * configInfo.outputSize.height / 4;
>
> - /*
> - * \todo Use the upcoming per-frame context API that will provide a
> - * frame index
> - */
> - frameCount_ = 0;
> -
> /* \todo Run this again when FrameDurationLimits is passed in */
> configureExposureModeHelpers(context.configuration.sensor.minShutterSpeed,
> context.configuration.sensor.maxShutterSpeed,
> @@ -224,122 +195,24 @@ void Agc::prepare(IPAContext &context, const uint32_t frame,
> params->module_en_update |= RKISP1_CIF_ISP_MODULE_HST;
> }
>
> -/**
> - * \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
> - */
> -utils::Duration Agc::filterExposure(utils::Duration exposureValue)
> -{
> - double speed = 0.2;
> -
> - /* Adapt instantly if we are in startup phase. */
> - if (frameCount_ < kNumStartupFrames)
> - speed = 1.0;
> -
> - /*
> - * If we are close to the desired result, go faster to avoid making
> - * multiple micro-adjustments.
> - * \todo Make this customisable?
> - */
> - if (filteredExposure_ < 1.2 * exposureValue &&
> - filteredExposure_ > 0.8 * exposureValue)
> - speed = sqrt(speed);
> -
> - filteredExposure_ = speed * exposureValue +
> - filteredExposure_ * (1.0 - speed);
> -
> - LOG(RkISP1Agc, Debug) << "After filtering, exposure " << filteredExposure_;
> -
> - return filteredExposure_;
> -}
> -
> -/**
> - * \brief Estimate the new exposure and gain values
> - * \param[inout] context The shared IPA Context
> - * \param[in] frameContext The FrameContext for this frame
> - * \param[in] yGain The gain calculated on the current brightness level
> - * \param[in] iqMeanGain The gain calculated based on the relative luminance target
> - */
> -void Agc::computeExposure(IPAContext &context, IPAFrameContext &frameContext,
> - double yGain, double iqMeanGain)
> +void Agc::fillMetadata(IPAContext &context, IPAFrameContext &frameContext,
> + ControlList &metadata)
> {
> - IPASessionConfiguration &configuration = context.configuration;
> -
> - /* Get the effective exposure and gain applied on the sensor. */
> - uint32_t exposure = frameContext.sensor.exposure;
> - double analogueGain = frameContext.sensor.gain;
> -
> - /* Use the highest of the two gain estimates. */
> - double evGain = std::max(yGain, iqMeanGain);
> -
> - utils::Duration minShutterSpeed = configuration.sensor.minShutterSpeed;
> - utils::Duration maxShutterSpeed = std::min(configuration.sensor.maxShutterSpeed,
> - kMaxShutterSpeed);
> -
> - double minAnalogueGain = std::max(configuration.sensor.minAnalogueGain,
> - kMinAnalogueGain);
> - double maxAnalogueGain = configuration.sensor.maxAnalogueGain;
> -
> - /* Consider within 1% of the target as correctly exposed. */
> - if (utils::abs_diff(evGain, 1.0) < 0.01)
> - return;
> -
> - /* extracted from Rpi::Agc::computeTargetExposure. */
> -
> - /* Calculate the shutter time in seconds. */
> - utils::Duration currentShutter = exposure * configuration.sensor.lineDuration;
> -
> - /*
> - * Update the exposure value for the next computation using the values
> - * of exposure and gain really used by the sensor.
> - */
> - utils::Duration effectiveExposureValue = currentShutter * analogueGain;
> -
> - LOG(RkISP1Agc, Debug) << "Actual total exposure " << currentShutter * analogueGain
> - << " Shutter speed " << currentShutter
> - << " Gain " << analogueGain
> - << " Needed ev gain " << evGain;
> -
> - /*
> - * Calculate the current exposure value for the scene as the latest
> - * exposure value applied multiplied by the new estimated gain.
> - */
> - utils::Duration exposureValue = effectiveExposureValue * evGain;
> -
> - /* Clamp the exposure value to the min and max authorized. */
> - utils::Duration maxTotalExposure = maxShutterSpeed * maxAnalogueGain;
> - exposureValue = std::min(exposureValue, maxTotalExposure);
> - LOG(RkISP1Agc, Debug) << "Target total exposure " << exposureValue
> - << ", maximum is " << maxTotalExposure;
> -
> - /*
> - * Divide the exposure value as new exposure and gain values.
> - * \todo estimate if we need to desaturate
> - */
> - exposureValue = filterExposure(exposureValue);
> + utils::Duration exposureTime = context.configuration.sensor.lineDuration
> + * frameContext.sensor.exposure;
> + metadata.set(controls::AnalogueGain, frameContext.sensor.gain);
> + metadata.set(controls::ExposureTime, exposureTime.get<std::micro>());
>
> - /*
> - * Push the shutter time up to the maximum first, and only then
> - * increase the gain.
> - */
> - utils::Duration shutterTime = std::clamp<utils::Duration>(exposureValue / minAnalogueGain,
> - minShutterSpeed, maxShutterSpeed);
> - double stepGain = std::clamp(exposureValue / shutterTime,
> - minAnalogueGain, maxAnalogueGain);
> - LOG(RkISP1Agc, Debug) << "Divided up shutter and gain are "
> - << shutterTime << " and "
> - << stepGain;
> + /* \todo Use VBlank value calculated from each frame exposure. */
> + uint32_t vTotal = context.configuration.sensor.size.height
> + + context.configuration.sensor.defVBlank;
> + utils::Duration frameDuration = context.configuration.sensor.lineDuration
> + * vTotal;
> + metadata.set(controls::FrameDuration, frameDuration.get<std::micro>());
> }
>
> /**
> * \brief Estimate the relative luminance of the frame with a given gain
> - * \param[in] expMeans The mean luminance values, from the RkISP1 statistics
> * \param[in] gain The gain to apply to the frame
> *
> * This function estimates the average relative luminance of the frame that
> @@ -353,8 +226,6 @@ void Agc::computeExposure(IPAContext &context, IPAFrameContext &frameContext,
> * YUV doesn't take into account the fact that the R, G and B components
> * contribute differently to the relative luminance.
> *
> - * \todo Have a dedicated YUV algorithm ?
> - *
> * The values are normalized to the [0.0, 1.0] range, where 1.0 corresponds to a
> * theoretical perfect reflector of 100% reference white.
> *
> @@ -363,47 +234,6 @@ void Agc::computeExposure(IPAContext &context, IPAFrameContext &frameContext,
> *
> * \return The relative luminance
> */
> -double Agc::estimateLuminance(Span<const uint8_t> expMeans, double gain)
> -{
> - double ySum = 0.0;
> -
> - /* Sum the averages, saturated to 255. */
> - for (uint8_t expMean : expMeans)
> - ySum += std::min(expMean * gain, 255.0);
> -
> - /* \todo Weight with the AWB gains */
> -
> - return ySum / expMeans.size() / 255;
> -}
> -
> -/**
> - * \brief Estimate the mean value of the top 2% of the histogram
> - * \param[in] hist The histogram statistics computed by the RkISP1
> - * \return The mean value of the top 2% of the histogram
> - */
> -double Agc::measureBrightness(Span<const uint32_t> hist) const
> -{
> - Histogram histogram{ hist };
> - /* Estimate the quantile mean of the top 2% of the histogram. */
> - return histogram.interQuantileMean(0.98, 1.0);
> -}
> -
> -void Agc::fillMetadata(IPAContext &context, IPAFrameContext &frameContext,
> - ControlList &metadata)
> -{
> - utils::Duration exposureTime = context.configuration.sensor.lineDuration
> - * frameContext.sensor.exposure;
> - metadata.set(controls::AnalogueGain, frameContext.sensor.gain);
> - metadata.set(controls::ExposureTime, exposureTime.get<std::micro>());
> -
> - /* \todo Use VBlank value calculated from each frame exposure. */
> - uint32_t vTotal = context.configuration.sensor.size.height
> - + context.configuration.sensor.defVBlank;
> - utils::Duration frameDuration = context.configuration.sensor.lineDuration
> - * vTotal;
> - metadata.set(controls::FrameDuration, frameDuration.get<std::micro>());
> -}
> -
> double Agc::estimateLuminance(double gain)
> {
> double ySum = 0.0;
> @@ -448,40 +278,7 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame,
> const rkisp1_cif_isp_stat *params = &stats->params;
> ASSERT(stats->meas_type & RKISP1_CIF_ISP_STAT_AUTOEXP);
>
> - Span<const uint8_t> ae{ params->ae.exp_mean, context.hw->numAeCells };
> - Span<const uint32_t> hist{
> - params->hist.hist_bins,
> - context.hw->numHistogramBins
> - };
> -
> - double iqMean = measureBrightness(hist);
> - double iqMeanGain = kEvGainTarget * hist.size() / iqMean;
> -
> - /*
> - * Estimate the gain needed to achieve a relative luminance target. To
> - * account for non-linearity caused by saturation, the value needs to be
> - * estimated in an iterative process, as multiplying by a gain will not
> - * increase the relative luminance by the same factor if some image
> - * regions are saturated.
> - */
> - double yGain = 1.0;
> - double yTarget = kRelativeLuminanceTarget;
> -
> - for (unsigned int i = 0; i < 8; i++) {
> - double yValue = estimateLuminance(ae, yGain);
> - double extra_gain = std::min(10.0, yTarget / (yValue + .001));
> -
> - yGain *= extra_gain;
> - LOG(RkISP1Agc, Debug) << "Y value: " << yValue
> - << ", Y target: " << yTarget
> - << ", gives gain " << yGain;
> - if (extra_gain < 1.01)
> - break;
> - }
> -
> - computeExposure(context, frameContext, yGain, iqMeanGain);
> - frameCount_++;
> -
> + Histogram hist({ params->hist.hist_bins, context.hw->numHistogramBins });
> expMeans_ = { params->ae.exp_mean, context.hw->numAeCells };
>
> /*
> @@ -498,7 +295,7 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame,
> std::tie(shutterTime, aGain, dGain) =
> calculateNewEv(context.activeState.agc.constraintMode,
> context.activeState.agc.exposureMode,
> - Histogram(hist), effectiveExposureValue);
> + hist, effectiveExposureValue);
>
> LOG(RkISP1Agc, Debug)
> << "Divided up shutter, analogue gain and digital gain are "
> diff --git a/src/ipa/rkisp1/algorithms/agc.h b/src/ipa/rkisp1/algorithms/agc.h
> index a8080228..a2c1f61a 100644
> --- a/src/ipa/rkisp1/algorithms/agc.h
> +++ b/src/ipa/rkisp1/algorithms/agc.h
> @@ -44,19 +44,10 @@ public:
> ControlList &metadata) override;
>
> private:
> - void computeExposure(IPAContext &Context, IPAFrameContext &frameContext,
> - double yGain, double iqMeanGain);
> - utils::Duration filterExposure(utils::Duration exposureValue);
> - double estimateLuminance(Span<const uint8_t> expMeans, double gain);
> - double measureBrightness(Span<const uint32_t> hist) const;
> void fillMetadata(IPAContext &context, IPAFrameContext &frameContext,
> ControlList &metadata);
> double estimateLuminance(double gain) override;
>
> - uint64_t frameCount_;
> -
> - utils::Duration filteredExposure_;
> -
> Span<const uint8_t> expMeans_;
> };
>
> --
> 2.34.1
>
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