[v3,22/23] libcamera: software_isp: Move exposure+gain to an algorithm module

20685 diff mbox series

This is the last step to fully convert software ISP to Algorithm-based
processing.

The newly introduced frameContext.sensor properties are set, and the
updated code moved, before calling Algorithm::process() to have the
values up-to-date in stats processing.

Resolves software ISP TODO #10.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
---
 src/ipa/simple/algorithms/agc.cpp     | 139 ++++++++++++++++++++++
 src/ipa/simple/algorithms/agc.h       |  36 ++++++
 src/ipa/simple/algorithms/meson.build |   1 +
 src/ipa/simple/data/uncalibrated.yaml |   1 +
 src/ipa/simple/ipa_context.cpp        |  11 ++
 src/ipa/simple/ipa_context.h          |  17 +++
 src/ipa/simple/soft_simple.cpp        | 159 +++++---------------------
 src/libcamera/software_isp/TODO       |  10 --
 8 files changed, 235 insertions(+), 139 deletions(-)
 create mode 100644 src/ipa/simple/algorithms/agc.cpp
 create mode 100644 src/ipa/simple/algorithms/agc.h

Milan Zamazal <mzamazal@redhat.com> writes:

> This is the last step to fully convert software ISP to Algorithm-based
> processing.
>
> The newly introduced frameContext.sensor properties are set, and the
> updated code moved, before calling Algorithm::process() to have the
> values up-to-date in stats processing.
>
> Resolves software ISP TODO #10.
>
> Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
> ---
>  src/ipa/simple/algorithms/agc.cpp     | 139 ++++++++++++++++++++++
>  src/ipa/simple/algorithms/agc.h       |  36 ++++++
>  src/ipa/simple/algorithms/meson.build |   1 +
>  src/ipa/simple/data/uncalibrated.yaml |   1 +
>  src/ipa/simple/ipa_context.cpp        |  11 ++
>  src/ipa/simple/ipa_context.h          |  17 +++
>  src/ipa/simple/soft_simple.cpp        | 159 +++++---------------------
>  src/libcamera/software_isp/TODO       |  10 --
>  8 files changed, 235 insertions(+), 139 deletions(-)
>  create mode 100644 src/ipa/simple/algorithms/agc.cpp
>  create mode 100644 src/ipa/simple/algorithms/agc.h
>
> diff --git a/src/ipa/simple/algorithms/agc.cpp b/src/ipa/simple/algorithms/agc.cpp
> new file mode 100644
> index 00000000..a80022ff
> --- /dev/null
> +++ b/src/ipa/simple/algorithms/agc.cpp
> @@ -0,0 +1,139 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2024, Red Hat Inc.
> + *
> + * Exposure and gain
> + */
> +
> +#include "agc.h"
> +
> +#include <stdint.h>
> +
> +#include <libcamera/base/log.h>
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(IPASoftExposure)
> +
> +namespace ipa::soft::algorithms {
> +
> +/*
> + * The number of bins to use for the optimal exposure calculations.
> + */
> +static constexpr unsigned int kExposureBinsCount = 5;
> +
> +/*
> + * The exposure is optimal when the mean sample value of the histogram is
> + * in the middle of the range.
> + */
> +static constexpr float kExposureOptimal = kExposureBinsCount / 2.0;
> +
> +/*
> + * The below value implements the hysteresis for the exposure adjustment.
> + * It is small enough to have the exposure close to the optimal, and is big
> + * enough to prevent the exposure from wobbling around the optimal value.
> + */
> +static constexpr float kExposureSatisfactory = 0.2;
> +
> +Agc::Agc()
> +{
> +}
> +
> +void Agc::updateExposure(IPAContext &context, double exposureMSV)
> +{
> +	/*
> +	 * kExpDenominator of 10 gives ~10% increment/decrement;
> +	 * kExpDenominator of 5 - about ~20%
> +	 */
> +	static constexpr uint8_t kExpDenominator = 10;
> +	static constexpr uint8_t kExpNumeratorUp = kExpDenominator + 1;
> +	static constexpr uint8_t kExpNumeratorDown = kExpDenominator - 1;
> +
> +	double next;
> +	int32_t &exposure = context.activeState.agc.exposure;
> +	double &again = context.activeState.agc.again;
> +
> +	if (exposureMSV < kExposureOptimal - kExposureSatisfactory) {
> +		next = exposure * kExpNumeratorUp / kExpDenominator;
> +		if (next - exposure < 1)
> +			exposure += 1;
> +		else
> +			exposure = next;
> +		if (exposure >= context.configuration.agc.exposureMax) {
> +			next = again * kExpNumeratorUp / kExpDenominator;
> +			if (next - again < context.configuration.agc.againMinStep)
> +				again += context.configuration.agc.againMinStep;
> +			else
> +				again = next;
> +		}
> +	}
> +
> +	if (exposureMSV > kExposureOptimal + kExposureSatisfactory) {
> +		if (exposure == context.configuration.agc.exposureMax &&
> +		    again > context.configuration.agc.againMin) {
> +			next = again * kExpNumeratorDown / kExpDenominator;
> +			if (again - next < context.configuration.agc.againMinStep)
> +				again -= context.configuration.agc.againMinStep;
> +			else
> +				again = next;
> +		} else {
> +			next = exposure * kExpNumeratorDown / kExpDenominator;
> +			if (exposure - next < 1)
> +				exposure -= 1;
> +			else
> +				exposure = next;
> +		}
> +	}
> +
> +	exposure = std::clamp(exposure, context.configuration.agc.exposureMin,
> +			      context.configuration.agc.exposureMax);
> +	again = std::clamp(again, context.configuration.agc.againMin,
> +			   context.configuration.agc.againMax);
> +
> +	LOG(IPASoftExposure, Debug)
> +		<< "exposureMSV " << exposureMSV
> +		<< " exp " << exposure << " again " << again;
> +}
> +
> +void Agc::process(IPAContext &context,
> +		  [[maybe_unused]] const uint32_t frame,
> +		  [[maybe_unused]] IPAFrameContext &frameContext,
> +		  const SwIspStats *stats,
> +		  [[maybe_unused]] ControlList &metadata)
> +{
> +	/*
> +	 * Calculate Mean Sample Value (MSV) according to formula from:
> +	 * https://www.araa.asn.au/acra/acra2007/papers/paper84final.pdf
> +	 */
> +	const auto &histogram = stats->yHistogram;
> +	const unsigned int blackLevelHistIdx =
> +		context.configuration.black.level * SwIspStats::kYHistogramSize;

This should use context.activeState.  I'll fix it in the next update.

(context.configuration.black.level should be assigned from the camera
helper, which optionally provides black level now.  I'm working on a
corresponding patch, which will be posted separately as it is not
refactoring.)

> +	const unsigned int histogramSize =
> +		SwIspStats::kYHistogramSize - blackLevelHistIdx;
> +	const unsigned int yHistValsPerBin = histogramSize / kExposureBinsCount;
> +	const unsigned int yHistValsPerBinMod =
> +		histogramSize / (histogramSize % kExposureBinsCount + 1);
> +	int exposureBins[kExposureBinsCount] = {};
> +	unsigned int denom = 0;
> +	unsigned int num = 0;
> +
> +	for (unsigned int i = 0; i < histogramSize; i++) {
> +		unsigned int idx = (i - (i / yHistValsPerBinMod)) / yHistValsPerBin;
> +		exposureBins[idx] += histogram[blackLevelHistIdx + i];
> +	}
> +
> +	for (unsigned int i = 0; i < kExposureBinsCount; i++) {
> +		LOG(IPASoftExposure, Debug) << i << ": " << exposureBins[i];
> +		denom += exposureBins[i];
> +		num += exposureBins[i] * (i + 1);
> +	}
> +
> +	float exposureMSV = (denom == 0 ? 0 : static_cast<float>(num) / denom);
> +	updateExposure(context, exposureMSV);
> +}
> +
> +REGISTER_IPA_ALGORITHM(Agc, "Agc")
> +
> +} /* namespace ipa::soft::algorithms */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/simple/algorithms/agc.h b/src/ipa/simple/algorithms/agc.h
> new file mode 100644
> index 00000000..a4aa656c
> --- /dev/null
> +++ b/src/ipa/simple/algorithms/agc.h
> @@ -0,0 +1,36 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2024, Red Hat Inc.
> + *
> + * Exposure and gain
> + */
> +
> +#pragma once
> +
> +#include "libcamera/internal/software_isp/swisp_stats.h"
> +
> +#include "algorithm.h"
> +#include "ipa_context.h"
> +
> +namespace libcamera {
> +
> +namespace ipa::soft::algorithms {
> +
> +class Agc : public Algorithm
> +{
> +public:
> +	Agc();
> +	~Agc() = default;
> +
> +	void process(IPAContext &context, const uint32_t frame,
> +		     IPAFrameContext &frameContext,
> +		     const SwIspStats *stats,
> +		     ControlList &metadata) override;
> +
> +private:
> +	void updateExposure(IPAContext &context, double exposureMSV);
> +};
> +
> +} /* namespace ipa::soft::algorithms */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/simple/algorithms/meson.build b/src/ipa/simple/algorithms/meson.build
> index 324c7b4e..0b178e17 100644
> --- a/src/ipa/simple/algorithms/meson.build
> +++ b/src/ipa/simple/algorithms/meson.build
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: CC0-1.0
>  
>  soft_simple_ipa_algorithms = files([
> +    'agc.cpp',
>      'blc.cpp',
>      'colors.cpp',
>  ])
> diff --git a/src/ipa/simple/data/uncalibrated.yaml b/src/ipa/simple/data/uncalibrated.yaml
> index 7e5149e5..7489c81f 100644
> --- a/src/ipa/simple/data/uncalibrated.yaml
> +++ b/src/ipa/simple/data/uncalibrated.yaml
> @@ -5,4 +5,5 @@ version: 1
>  algorithms:
>    - BlackLevel:
>    - Colors:
> +  - Agc:
>  ...
> diff --git a/src/ipa/simple/ipa_context.cpp b/src/ipa/simple/ipa_context.cpp
> index 5fa492cb..3f94bbeb 100644
> --- a/src/ipa/simple/ipa_context.cpp
> +++ b/src/ipa/simple/ipa_context.cpp
> @@ -77,6 +77,17 @@ namespace libcamera::ipa::soft {
>   * \brief Gain of blue color
>   */
>  
> +/**
> + * \var IPAActiveState::agc
> + * \brief Context for the AGC algorithm
> + *
> + * \var IPAActiveState::agc.exposure
> + * \brief Current exposure value
> + *
> + * \var IPAActiveState::agc.again
> + * \brief Current analog gain value
> + */
> +
>  /**
>   * \var IPAActiveState::gamma
>   * \brief Context for gamma in the Colors algorithm
> diff --git a/src/ipa/simple/ipa_context.h b/src/ipa/simple/ipa_context.h
> index 552d6cde..40a2efc2 100644
> --- a/src/ipa/simple/ipa_context.h
> +++ b/src/ipa/simple/ipa_context.h
> @@ -10,6 +10,8 @@
>  
>  #include <array>
>  
> +#include <libcamera/controls.h>
> +
>  #include <libipa/fc_queue.h>
>  
>  namespace libcamera {
> @@ -18,6 +20,13 @@ namespace ipa::soft {
>  
>  struct IPASessionConfiguration {
>  	float gamma;
> +	struct {
> +		int32_t exposureMin, exposureMax;
> +		double againMin, againMax, againMinStep;
> +	} agc;
> +	struct {
> +		double level;
> +	} black;
>  };
>  
>  struct IPAActiveState {
> @@ -29,6 +38,10 @@ struct IPAActiveState {
>  		double green;
>  		double blue;
>  	} gains;
> +	struct {
> +		int32_t exposure;
> +		double again;
> +	} agc;
>  	static constexpr unsigned int kGammaLookupSize = 1024;
>  	struct {
>  		std::array<double, kGammaLookupSize> gammaTable;
> @@ -37,6 +50,10 @@ struct IPAActiveState {
>  };
>  
>  struct IPAFrameContext : public FrameContext {
> +	struct {
> +		uint32_t exposure;
> +		double gain;
> +	} sensor;
>  };
>  
>  struct IPAContext {
> diff --git a/src/ipa/simple/soft_simple.cpp b/src/ipa/simple/soft_simple.cpp
> index cf2d628d..547d0fcf 100644
> --- a/src/ipa/simple/soft_simple.cpp
> +++ b/src/ipa/simple/soft_simple.cpp
> @@ -33,23 +33,6 @@ LOG_DEFINE_CATEGORY(IPASoft)
>  
>  namespace ipa::soft {
>  
> -/*
> - * The number of bins to use for the optimal exposure calculations.
> - */
> -static constexpr unsigned int kExposureBinsCount = 5;
> -
> -/*
> - * The exposure is optimal when the mean sample value of the histogram is
> - * in the middle of the range.
> - */
> -static constexpr float kExposureOptimal = kExposureBinsCount / 2.0;
> -
> -/*
> - * The below value implements the hysteresis for the exposure adjustment.
> - * It is small enough to have the exposure close to the optimal, and is big
> - * enough to prevent the exposure from wobbling around the optimal value.
> - */
> -static constexpr float kExposureSatisfactory = 0.2;
>  /* Maximum number of frame contexts to be held */
>  static constexpr uint32_t kMaxFrameContexts = 16;
>  
> @@ -57,8 +40,7 @@ class IPASoftSimple : public ipa::soft::IPASoftInterface, public Module
>  {
>  public:
>  	IPASoftSimple()
> -		: params_(nullptr), stats_(nullptr),
> -		  context_({ {}, {}, { kMaxFrameContexts } })
> +		: context_({ {}, {}, { kMaxFrameContexts } })
>  	{
>  	}
>  
> @@ -91,11 +73,6 @@ private:
>  
>  	/* Local parameter storage */
>  	struct IPAContext context_;
> -
> -	int32_t exposureMin_, exposureMax_;
> -	int32_t exposure_;
> -	double againMin_, againMax_, againMinStep_;
> -	double again_;
>  };
>  
>  IPASoftSimple::~IPASoftSimple()
> @@ -206,20 +183,23 @@ int IPASoftSimple::configure(const IPAConfigInfo &configInfo)
>  	const ControlInfo &exposureInfo = sensorInfoMap_.find(V4L2_CID_EXPOSURE)->second;
>  	const ControlInfo &gainInfo = sensorInfoMap_.find(V4L2_CID_ANALOGUE_GAIN)->second;
>  
> -	exposureMin_ = exposureInfo.min().get<int32_t>();
> -	exposureMax_ = exposureInfo.max().get<int32_t>();
> -	if (!exposureMin_) {
> +	context_.configuration.agc.exposureMin = exposureInfo.min().get<int32_t>();
> +	context_.configuration.agc.exposureMax = exposureInfo.max().get<int32_t>();
> +	if (!context_.configuration.agc.exposureMin) {
>  		LOG(IPASoft, Warning) << "Minimum exposure is zero, that can't be linear";
> -		exposureMin_ = 1;
> +		context_.configuration.agc.exposureMin = 1;
>  	}
>  
>  	int32_t againMin = gainInfo.min().get<int32_t>();
>  	int32_t againMax = gainInfo.max().get<int32_t>();
>  
>  	if (camHelper_) {
> -		againMin_ = camHelper_->gain(againMin);
> -		againMax_ = camHelper_->gain(againMax);
> -		againMinStep_ = (againMax_ - againMin_) / 100.0;
> +		context_.configuration.agc.againMin = camHelper_->gain(againMin);
> +		context_.configuration.agc.againMax = camHelper_->gain(againMax);
> +		context_.configuration.agc.againMinStep =
> +			(context_.configuration.agc.againMax -
> +			 context_.configuration.agc.againMin) /
> +			100.0;
>  	} else {
>  		/*
>  		 * The camera sensor gain (g) is usually not equal to the value written
> @@ -231,13 +211,14 @@ int IPASoftSimple::configure(const IPAConfigInfo &configInfo)
>  		 * the AGC algorithm (abrupt near one edge, and very small near the
>  		 * other) we limit the range of the gain values used.
>  		 */
> -		againMax_ = againMax;
> +		context_.configuration.agc.againMax = againMax;
>  		if (!againMin) {
>  			LOG(IPASoft, Warning)
>  				<< "Minimum gain is zero, that can't be linear";
> -			againMin_ = std::min(100, againMin / 2 + againMax / 2);
> +			context_.configuration.agc.againMin =
> +				std::min(100, againMin / 2 + againMax / 2);
>  		}
> -		againMinStep_ = 1.0;
> +		context_.configuration.agc.againMinStep = 1.0;
>  	}
>  
>  	for (auto const &algo : algorithms()) {
> @@ -246,9 +227,12 @@ int IPASoftSimple::configure(const IPAConfigInfo &configInfo)
>  			return ret;
>  	}
>  
> -	LOG(IPASoft, Info) << "Exposure " << exposureMin_ << "-" << exposureMax_
> -			   << ", gain " << againMin_ << "-" << againMax_
> -			   << " (" << againMinStep_ << ")";
> +	LOG(IPASoft, Info)
> +		<< "Exposure " << context_.configuration.agc.exposureMin << "-"
> +		<< context_.configuration.agc.exposureMax
> +		<< ", gain " << context_.configuration.agc.againMin << "-"
> +		<< context_.configuration.agc.againMax
> +		<< " (" << context_.configuration.agc.againMinStep << ")";
>  
>  	return 0;
>  }
> @@ -284,6 +268,12 @@ void IPASoftSimple::processStats(
>  	const ControlList &sensorControls)
>  {
>  	IPAFrameContext &frameContext = context_.frameContexts.get(frame);
> +
> +	frameContext.sensor.exposure =
> +		sensorControls.get(V4L2_CID_EXPOSURE).get<int32_t>();
> +	int32_t again = sensorControls.get(V4L2_CID_ANALOGUE_GAIN).get<int32_t>();
> +	frameContext.sensor.gain = camHelper_ ? camHelper_->gain(again) : again;
> +
>  	/*
>  	 * Software ISP currently does not produce any metadata. Use an empty
>  	 * ControlList for now.
> @@ -294,37 +284,6 @@ void IPASoftSimple::processStats(
>  	for (auto const &algo : algorithms())
>  		algo->process(context_, frame, frameContext, stats_, metadata);
>  
> -	/* \todo Switch to the libipa/algorithm.h API someday. */
> -
> -	/*
> -	 * Calculate Mean Sample Value (MSV) according to formula from:
> -	 * https://www.araa.asn.au/acra/acra2007/papers/paper84final.pdf
> -	 */
> -	const uint8_t blackLevel = context_.activeState.black.level;
> -	const unsigned int blackLevelHistIdx =
> -		blackLevel / (256 / SwIspStats::kYHistogramSize);
> -	const unsigned int histogramSize =
> -		SwIspStats::kYHistogramSize - blackLevelHistIdx;
> -	const unsigned int yHistValsPerBin = histogramSize / kExposureBinsCount;
> -	const unsigned int yHistValsPerBinMod =
> -		histogramSize / (histogramSize % kExposureBinsCount + 1);
> -	int exposureBins[kExposureBinsCount] = {};
> -	unsigned int denom = 0;
> -	unsigned int num = 0;
> -
> -	for (unsigned int i = 0; i < histogramSize; i++) {
> -		unsigned int idx = (i - (i / yHistValsPerBinMod)) / yHistValsPerBin;
> -		exposureBins[idx] += stats_->yHistogram[blackLevelHistIdx + i];
> -	}
> -
> -	for (unsigned int i = 0; i < kExposureBinsCount; i++) {
> -		LOG(IPASoft, Debug) << i << ": " << exposureBins[i];
> -		denom += exposureBins[i];
> -		num += exposureBins[i] * (i + 1);
> -	}
> -
> -	float exposureMSV = static_cast<float>(num) / denom;
> -
>  	/* Sanity check */
>  	if (!sensorControls.contains(V4L2_CID_EXPOSURE) ||
>  	    !sensorControls.contains(V4L2_CID_ANALOGUE_GAIN)) {
> @@ -332,72 +291,14 @@ void IPASoftSimple::processStats(
>  		return;
>  	}
>  
> -	exposure_ = sensorControls.get(V4L2_CID_EXPOSURE).get<int32_t>();
> -	int32_t again = sensorControls.get(V4L2_CID_ANALOGUE_GAIN).get<int32_t>();
> -	again_ = camHelper_ ? camHelper_->gain(again) : again;
> -
> -	updateExposure(exposureMSV);
> -
>  	ControlList ctrls(sensorInfoMap_);
>  
> -	ctrls.set(V4L2_CID_EXPOSURE, exposure_);
> +	auto &againNew = context_.activeState.agc.again;
> +	ctrls.set(V4L2_CID_EXPOSURE, context_.activeState.agc.exposure);
>  	ctrls.set(V4L2_CID_ANALOGUE_GAIN,
> -		  static_cast<int32_t>(camHelper_ ? camHelper_->gainCode(again_) : again_));
> +		  static_cast<int32_t>(camHelper_ ? camHelper_->gainCode(againNew) : againNew));
>  
>  	setSensorControls.emit(ctrls);
> -
> -	LOG(IPASoft, Debug) << "exposureMSV " << exposureMSV
> -			    << " exp " << exposure_ << " again " << again_
> -			    << " gain R/B " << context_.activeState.gains.red
> -			    << "/" << context_.activeState.gains.blue
> -			    << " black level " << static_cast<unsigned int>(blackLevel);
> -}
> -
> -void IPASoftSimple::updateExposure(double exposureMSV)
> -{
> -	/*
> -	 * kExpDenominator of 10 gives ~10% increment/decrement;
> -	 * kExpDenominator of 5 - about ~20%
> -	 */
> -	static constexpr uint8_t kExpDenominator = 10;
> -	static constexpr uint8_t kExpNumeratorUp = kExpDenominator + 1;
> -	static constexpr uint8_t kExpNumeratorDown = kExpDenominator - 1;
> -
> -	double next;
> -
> -	if (exposureMSV < kExposureOptimal - kExposureSatisfactory) {
> -		next = exposure_ * kExpNumeratorUp / kExpDenominator;
> -		if (next - exposure_ < 1)
> -			exposure_ += 1;
> -		else
> -			exposure_ = next;
> -		if (exposure_ >= exposureMax_) {
> -			next = again_ * kExpNumeratorUp / kExpDenominator;
> -			if (next - again_ < againMinStep_)
> -				again_ += againMinStep_;
> -			else
> -				again_ = next;
> -		}
> -	}
> -
> -	if (exposureMSV > kExposureOptimal + kExposureSatisfactory) {
> -		if (exposure_ == exposureMax_ && again_ > againMin_) {
> -			next = again_ * kExpNumeratorDown / kExpDenominator;
> -			if (again_ - next < againMinStep_)
> -				again_ -= againMinStep_;
> -			else
> -				again_ = next;
> -		} else {
> -			next = exposure_ * kExpNumeratorDown / kExpDenominator;
> -			if (exposure_ - next < 1)
> -				exposure_ -= 1;
> -			else
> -				exposure_ = next;
> -		}
> -	}
> -
> -	exposure_ = std::clamp(exposure_, exposureMin_, exposureMax_);
> -	again_ = std::clamp(again_, againMin_, againMax_);
>  }
>  
>  std::string IPASoftSimple::logPrefix() const
> diff --git a/src/libcamera/software_isp/TODO b/src/libcamera/software_isp/TODO
> index 6b1cb57a..42828895 100644
> --- a/src/libcamera/software_isp/TODO
> +++ b/src/libcamera/software_isp/TODO
> @@ -218,16 +218,6 @@ Yes, because, well... all the other IPAs were doing that...
>  
>  ---
>  
> -10. Switch to libipa/algorithm.h API in processStats
> -
> ->> void IPASoftSimple::processStats(const ControlList &sensorControls)
> ->>
> -> Do you envision switching to the libipa/algorithm.h API at some point ?
> -
> -At some point, yes.
> -
> ----
> -
>  13. Improve black level and colour gains application
>  
>  I think the black level should eventually be moved before debayering, and