/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* * Copyright (C) 2021, Google Inc. * * camera_sensor_helper.cpp - Helper class that performs sensor-specific * parameter computations */ #include "camera_sensor_helper.h" #include <cmath> #include <libcamera/base/log.h> /** * \file camera_sensor_helper.h * \brief Helper class that performs sensor-specific parameter computations * * Computation of sensor configuration parameters is a sensor specific * operation. Each CameraHelper derived class computes the value of * configuration parameters, for example the analogue gain value, using * sensor-specific functions and constants. * * Every subclass of CameraSensorHelper shall be registered with libipa using * the REGISTER_CAMERA_SENSOR_HELPER() macro. */ namespace libcamera { LOG_DEFINE_CATEGORY(CameraSensorHelper) namespace ipa { /** * \class CameraSensorHelper * \brief Base class for computing sensor tuning parameters using * sensor-specific constants * * Instances derived from CameraSensorHelper class are sensor-specific. * Each supported sensor will have an associated base class defined. */ /** * \brief Construct a CameraSensorHelper instance * * CameraSensorHelper derived class instances shall never be constructed * manually but always through the CameraSensorHelperFactoryBase::create() * function. */ /** * \brief Compute gain code from the analogue gain absolute value * \param[in] gain The real gain to pass * * This function aims to abstract the calculation of the gain letting the IPA * use the real gain for its estimations. * * \return The gain code to pass to V4L2 */ uint32_t CameraSensorHelper::gainCode(double gain) const { const AnalogueGainConstants &k = gainConstants_; switch (gainType_) { case AnalogueGainLinear: ASSERT(k.linear.m0 == 0 || k.linear.m1 == 0); return (k.linear.c0 - k.linear.c1 * gain) / (k.linear.m1 * gain - k.linear.m0); case AnalogueGainExponential: ASSERT(k.exp.a != 0 && k.exp.m != 0); return std::log2(gain / k.exp.a) / k.exp.m; default: ASSERT(false); return 0; } } /** * \brief Compute the real gain from the V4L2 subdev control gain code * \param[in] gainCode The V4L2 subdev control gain * * This function aims to abstract the calculation of the gain letting the IPA * use the real gain for its estimations. It is the counterpart of the function * CameraSensorHelper::gainCode. * * \return The real gain */ double CameraSensorHelper::gain(uint32_t gainCode) const { const AnalogueGainConstants &k = gainConstants_; double gain = static_cast<double>(gainCode); switch (gainType_) { case AnalogueGainLinear: ASSERT(k.linear.m0 == 0 || k.linear.m1 == 0); return (k.linear.m0 * gain + k.linear.c0) / (k.linear.m1 * gain + k.linear.c1); case AnalogueGainExponential: ASSERT(k.exp.a != 0 && k.exp.m != 0); return k.exp.a * std::exp2(k.exp.m * gain); default: ASSERT(false); return 0.0; } } /** * \enum CameraSensorHelper::AnalogueGainType * \brief The gain calculation modes as defined by the MIPI CCS * * Describes the image sensor analogue gain capabilities. * Two modes are possible, depending on the sensor: Linear and Exponential. */ /** * \var CameraSensorHelper::AnalogueGainLinear * \brief Gain is computed using linear gain estimation * * The relationship between the integer gain parameter and the resulting gain * multiplier is given by the following equation: * * \f$gain=\frac{m0x+c0}{m1x+c1}\f$ * * Where 'x' is the gain control parameter, and m0, m1, c0 and c1 are * image-sensor-specific constants of the sensor. * These constants are static parameters, and for any given image sensor either * m0 or m1 shall be zero. * * The full Gain equation therefore reduces to either: * * \f$gain=\frac{c0}{m1x+c1}\f$ or \f$\frac{m0x+c0}{c1}\f$ */ /** * \var CameraSensorHelper::AnalogueGainExponential * \brief Gain is expressed using an exponential model * * The relationship between the integer gain parameter and the resulting gain * multiplier is given by the following equation: * * \f$gain = a \cdot 2^{m \cdot x}\f$ * * Where 'x' is the gain control parameter, and 'a' and 'm' are image * sensor-specific constants. * * This is a subset of the MIPI CCS exponential gain model with the linear * factor 'a' being a constant, but with the exponent being configurable * through the 'm' coefficient. * * When the gain is expressed in dB, 'a' is equal to 1 and 'm' to * \f$log_{2}{10^{\frac{1}{20}}}\f$. */ /** * \struct CameraSensorHelper::AnalogueGainLinearConstants * \brief Analogue gain constants for the linear gain model * * \var CameraSensorHelper::AnalogueGainLinearConstants::m0 * \brief Constant used in the linear gain coding/decoding * * \note Either m0 or m1 shall be zero. * * \var CameraSensorHelper::AnalogueGainLinearConstants::c0 * \brief Constant used in the linear gain coding/decoding * * \var CameraSensorHelper::AnalogueGainLinearConstants::m1 * \brief Constant used in the linear gain coding/decoding * * \note Either m0 or m1 shall be zero. * * \var CameraSensorHelper::AnalogueGainLinearConstants::c1 * \brief Constant used in the linear gain coding/decoding */ /** * \struct CameraSensorHelper::AnalogueGainExpConstants * \brief Analogue gain constants for the exponential gain model * * \var CameraSensorHelper::AnalogueGainExpConstants::a * \brief Constant used in the exponential gain coding/decoding * * \var CameraSensorHelper::AnalogueGainExpConstants::m * \brief Constant used in the exponential gain coding/decoding */ /** * \struct CameraSensorHelper::AnalogueGainConstants * \brief Analogue gain model constants * * This union stores the constants used to calculate the analogue gain. The * CameraSensorHelper::gainType_ variable selects which union member is valid. * * \var CameraSensorHelper::AnalogueGainConstants::linear * \brief Constants for the linear gain model * * \var CameraSensorHelper::AnalogueGainConstants::exp * \brief Constants for the exponential gain model */ /** * \var CameraSensorHelper::gainType_ * \brief The analogue gain model type */ /** * \var CameraSensorHelper::gainConstants_ * \brief The analogue gain parameters used for calculation * * The analogue gain is calculated through a formula, and its parameters are * sensor specific. Use this variable to store the values at init time. */ /** * \class CameraSensorHelperFactoryBase * \brief Base class for camera sensor helper factories * * The CameraSensorHelperFactoryBase class is the base of all specializations of * the CameraSensorHelperFactory class template. It implements the factory * registration, maintains a registry of factories, and provides access to the * registered factories. */ /** * \brief Construct a camera sensor helper factory base * \param[in] name Name of the camera sensor helper class * * Creating an instance of the factory base registers it with the global list of * factories, accessible through the factories() function. * * The factory \a name is used to look up factories and shall be unique. */ CameraSensorHelperFactoryBase::CameraSensorHelperFactoryBase(const std::string name) : name_(name) { registerType(this); } /** * \brief Create an instance of the CameraSensorHelper corresponding to * a named factory * \param[in] name Name of the factory * * \return A unique pointer to a new instance of the CameraSensorHelper subclass * corresponding to the named factory or a null pointer if no such factory * exists */ std::unique_ptr<CameraSensorHelper> CameraSensorHelperFactoryBase::create(const std::string &name) { const std::vector<CameraSensorHelperFactoryBase *> &factories = CameraSensorHelperFactoryBase::factories(); for (const CameraSensorHelperFactoryBase *factory : factories) { if (name != factory->name_) continue; return factory->createInstance(); } return nullptr; } /** * \brief Add a camera sensor helper class to the registry * \param[in] factory Factory to use to construct the camera sensor helper * * The caller is responsible to guarantee the uniqueness of the camera sensor * helper name. */ void CameraSensorHelperFactoryBase::registerType(CameraSensorHelperFactoryBase *factory) { std::vector<CameraSensorHelperFactoryBase *> &factories = CameraSensorHelperFactoryBase::factories(); factories.push_back(factory); } /** * \brief Retrieve the list of all camera sensor helper factories * \return The list of camera sensor helper factories */ std::vector<CameraSensorHelperFactoryBase *> &CameraSensorHelperFactoryBase::factories() { /* * The static factories map is defined inside the function to ensure * it gets initialized on first use, without any dependency on link * order. */ static std::vector<CameraSensorHelperFactoryBase *> factories; return factories; } /** * \class CameraSensorHelperFactory * \brief Registration of CameraSensorHelperFactory classes and creation of instances * \tparam _Helper The camera sensor helper class type for this factory * * To facilitate discovery and instantiation of CameraSensorHelper classes, the * CameraSensorHelperFactory class implements auto-registration of camera sensor * helpers. Each CameraSensorHelper subclass shall register itself using the * REGISTER_CAMERA_SENSOR_HELPER() macro, which will create a corresponding * instance of a CameraSensorHelperFactory subclass and register it with the * static list of factories. */ /** * \fn CameraSensorHelperFactory::CameraSensorHelperFactory(const char *name) * \brief Construct a camera sensor helper factory * \param[in] name Name of the camera sensor helper class * * Creating an instance of the factory registers it with the global list of * factories, accessible through the CameraSensorHelperFactoryBase::factories() * function. * * The factory \a name is used to look up factories and shall be unique. */ /** * \fn CameraSensorHelperFactory::createInstance() const * \brief Create an instance of the CameraSensorHelper corresponding to the * factory * * \return A unique pointer to a newly constructed instance of the * CameraSensorHelper subclass corresponding to the factory */ /** * \def REGISTER_CAMERA_SENSOR_HELPER * \brief Register a camera sensor helper with the camera sensor helper factory * \param[in] name Sensor model name used to register the class * \param[in] helper Class name of CameraSensorHelper derived class to register * * Register a CameraSensorHelper subclass with the factory and make it available * to try and match sensors. */ /* ----------------------------------------------------------------------------- * Sensor-specific subclasses */ #ifndef __DOXYGEN__ /* * Helper function to compute the m parameter of the exponential gain model * when the gain code is expressed in dB. */ static constexpr double expGainDb(double step) { constexpr double log2_10 = 3.321928094887362; /* * The gain code is expressed in step * dB (e.g. in 0.1 dB steps): * * G_code = G_dB/step = 20/step*log10(G_linear) * * Inverting the formula, we get * * G_linear = 10^(step/20*G_code) = 2^(log2(10)*step/20*G_code) */ return log2_10 * step / 20; } class CameraSensorHelperAr0521 : public CameraSensorHelper { public: uint32_t gainCode(double gain) const override; double gain(uint32_t gainCode) const override; private: static constexpr double kStep_ = 16; }; uint32_t CameraSensorHelperAr0521::gainCode(double gain) const { gain = std::clamp(gain, 1.0, 15.5); unsigned int coarse = std::log2(gain); unsigned int fine = (gain / (1 << coarse) - 1) * kStep_; return (coarse << 4) | (fine & 0xf); } double CameraSensorHelperAr0521::gain(uint32_t gainCode) const { unsigned int coarse = gainCode >> 4; unsigned int fine = gainCode & 0xf; return (1 << coarse) * (1 + fine / kStep_); } REGISTER_CAMERA_SENSOR_HELPER("ar0521", CameraSensorHelperAr0521) class CameraSensorHelperImx219 : public CameraSensorHelper { public: CameraSensorHelperImx219() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 256, -1, 256 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx219", CameraSensorHelperImx219) class CameraSensorHelperImx258 : public CameraSensorHelper { public: CameraSensorHelperImx258() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 512, -1, 512 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx258", CameraSensorHelperImx258) class CameraSensorHelperImx290 : public CameraSensorHelper { public: CameraSensorHelperImx290() { gainType_ = AnalogueGainExponential; gainConstants_.exp = { 1.0, expGainDb(0.3) }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx290", CameraSensorHelperImx290) class CameraSensorHelperImx296 : public CameraSensorHelper { public: CameraSensorHelperImx296() { gainType_ = AnalogueGainExponential; gainConstants_.exp = { 1.0, expGainDb(0.1) }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx296", CameraSensorHelperImx296) class CameraSensorHelperImx477 : public CameraSensorHelper { public: CameraSensorHelperImx477() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 1024, -1, 1024 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx477", CameraSensorHelperImx477) class CameraSensorHelperOv2740 : public CameraSensorHelper { public: CameraSensorHelperOv2740() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov2740", CameraSensorHelperOv2740) class CameraSensorHelperOv5640 : public CameraSensorHelper { public: CameraSensorHelperOv5640() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 16 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5640", CameraSensorHelperOv5640) class CameraSensorHelperOv5670 : public CameraSensorHelper { public: CameraSensorHelperOv5670() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5670", CameraSensorHelperOv5670) class CameraSensorHelperOv5675 : public CameraSensorHelper { public: CameraSensorHelperOv5675() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5675", CameraSensorHelperOv5675) class CameraSensorHelperOv5693 : public CameraSensorHelper { public: CameraSensorHelperOv5693() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 16 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5693", CameraSensorHelperOv5693) class CameraSensorHelperOv8865 : public CameraSensorHelper { public: CameraSensorHelperOv8865() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov8865", CameraSensorHelperOv8865) class CameraSensorHelperOv13858 : public CameraSensorHelper { public: CameraSensorHelperOv13858() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov13858", CameraSensorHelperOv13858) #endif /* __DOXYGEN__ */ } /* namespace ipa */ } /* namespace libcamera */