agc_mean_luminance.h

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2024 Ideas on Board Oy
 *
 agc_mean_luminance.h - Base class for mean luminance AGC algorithms
 */
 
#pragma once
 
#include <map>
#include <memory>
#include <vector>
 
#include <libcamera/base/utils.h>
 
#include "libcamera/internal/value_node.h"
 
#include "exposure_mode_helper.h"
#include "histogram.h"
#include "pwl.h"
 
namespace libcamera {
 
namespace ipa {
 
class AgcMeanLuminance
{
public:
    AgcMeanLuminance();
    ~AgcMeanLuminance();
 
    struct AgcConstraint {
        enum class Bound {
            Lower = 0,
            Upper = 1
        };
        Bound bound;
        double qLo;
        double qHi;
        Pwl yTarget;
    };
 
    struct Traits {
        virtual ~Traits() = default;
        virtual double estimateLuminance(double gain) const = 0;
    };
 
    void configure(utils::Duration lineDuration, const CameraSensorHelper *sensorHelper);
    int parseTuningData(const ValueNode &tuningData);
 
    void setLimits(utils::Duration minExposureTime, utils::Duration maxExposureTime,
               double minGain, double maxGain, std::vector<AgcConstraint> constraints);
 
    const std::map<int32_t, std::vector<AgcConstraint>> &constraintModes() const
    {
        return constraintModes_;
    }
 
    const std::map<int32_t, ExposureModeHelper> &exposureModeHelpers() const
    {
        return exposureModeHelpers_;
    }
 
    struct Params {
        const Traits &traits;
        const Histogram &yHist;
        utils::Duration effectiveExposureValue;
        uint32_t constraintModeIndex;
        uint32_t exposureModeIndex;
        double lux = 0;
        double exposureCompensation = 1;
    };
 
    struct Result : ExposureModeHelper::Result {
        double yTarget;
    };
 
    [[nodiscard]] Result calculateNewEv(const Params &params);
 
    double effectiveYTarget(double lux, double exposureCompensation) const;
 
private:
    int parseRelativeLuminanceTarget(const ValueNode &tuningData);
    int parseConstraint(const ValueNode &modeDict, int32_t id);
    int parseConstraintModes(const ValueNode &tuningData);
    int parseExposureModes(const ValueNode &tuningData);
    double estimateInitialGain(const Traits &traits, double yTarget) const;
    double constraintClampGain(const Params &params, double gain) const;
    utils::Duration filterExposure(utils::Duration exposureValue);
 
    utils::Duration filteredExposure_;
    mutable bool luxWarningEnabled_;
    Pwl relativeLuminanceTarget_;
    uint64_t frameCount_;
 
    std::vector<AgcConstraint> additionalConstraints_;
    std::map<int32_t, std::vector<AgcConstraint>> constraintModes_;
    std::map<int32_t, ExposureModeHelper> exposureModeHelpers_;
};
 
} /* namespace ipa */
 
} /* namespace libcamera */