/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* * Copyright (C) 2021, Google Inc. * * Helper class that performs sensor-specific * parameter computations */ #include "camera_sensor_helper.h" #include #include #include /** * \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. */ /** * \fn CameraSensorHelper::CameraSensorHelper() * \brief Construct a CameraSensorHelper instance * * CameraSensorHelper derived class instances shall never be constructed * manually but always through the CameraSensorHelperFactoryBase::create() * function. */ /** * \fn CameraSensorHelper::blackLevel() * \brief Fetch the black level of the sensor * * This function returns the black level of the sensor scaled to a 16bit pixel * width. If it is unknown an empty optional is returned. * * \todo Fill the blanks and add pedestal values for all supported sensors. Once * done, drop the std::optional<>. * * Black levels are typically the result of the following phenomena: * - Pedestal added by the sensor to pixel values. They are typically fixed, * sometimes programmable and should be reported in datasheets (but * documentation is not always available). * - Dark currents and other physical effects that add charge to pixels in the * absence of light. Those can depend on the integration time and the sensor * die temperature, and their contribution to pixel values depend on the * sensor gains. * * The pedestal is usually the value with the biggest contribution to the * overall black level. In most cases it is either known before or in rare cases * (there is not a single driver with such a control in the linux kernel) can be * queried from the sensor. This function provides that fixed, known value. * * \return The black level of the sensor, or std::nullopt if not known */ /** * \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(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::blackLevel_ * \brief The black level of the sensor * \sa CameraSensorHelper::blackLevel() */ /** * \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 CameraSensorHelperFactoryBase::create(const std::string &name) { const std::vector &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 &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::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 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 CameraSensorHelperAr0144 : public CameraSensorHelper { public: CameraSensorHelperAr0144() { /* Power-on default value: 168 at 12bits. */ blackLevel_ = 2688; } uint32_t gainCode(double gain) const override { /* The recommended minimum gain is 1.6842 to avoid artifacts. */ gain = std::clamp(gain, 1.0 / (1.0 - 13.0 / 32.0), 18.45); /* * The analogue gain is made of a coarse exponential gain in * the range [2^0, 2^4] and a fine inversely linear gain in the * range [1.0, 2.0[. There is an additional fixed 1.153125 * multiplier when the coarse gain reaches 2^2. */ if (gain > 4.0) gain /= 1.153125; unsigned int coarse = std::log2(gain); unsigned int fine = (1 - (1 << coarse) / gain) * 32; /* The fine gain rounding depends on the coarse gain. */ if (coarse == 1 || coarse == 3) fine &= ~1; else if (coarse == 4) fine &= ~3; return (coarse << 4) | (fine & 0xf); } double gain(uint32_t gainCode) const override { unsigned int coarse = gainCode >> 4; unsigned int fine = gainCode & 0xf; unsigned int d1; double d2, m; switch (coarse) { default: case 0: d1 = 1; d2 = 32.0; m = 1.0; break; case 1: d1 = 2; d2 = 16.0; m = 1.0; break; case 2: d1 = 1; d2 = 32.0; m = 1.153125; break; case 3: d1 = 2; d2 = 16.0; m = 1.153125; break; case 4: d1 = 4; d2 = 8.0; m = 1.153125; break; } /* * With infinite precision, the calculated gain would be exact, * and the reverse conversion with gainCode() would produce the * same gain code. In the real world, rounding errors may cause * the calculated gain to be lower by an amount negligible for * all purposes, except for the reverse conversion. Converting * the gain to a gain code could then return the quantized value * just lower than the original gain code. To avoid this, tests * showed that adding the machine epsilon to the multiplier m is * sufficient. */ m += std::numeric_limits::epsilon(); return m * (1 << coarse) / (1.0 - (fine / d1) / d2); } private: static constexpr double kStep_ = 16; }; REGISTER_CAMERA_SENSOR_HELPER("ar0144", CameraSensorHelperAr0144) class CameraSensorHelperAr0521 : public CameraSensorHelper { public: uint32_t gainCode(double gain) const override { 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 gain(uint32_t gainCode) const override { unsigned int coarse = gainCode >> 4; unsigned int fine = gainCode & 0xf; return (1 << coarse) * (1 + fine / kStep_); } private: static constexpr double kStep_ = 16; }; REGISTER_CAMERA_SENSOR_HELPER("ar0521", CameraSensorHelperAr0521) class CameraSensorHelperImx214 : public CameraSensorHelper { public: CameraSensorHelperImx214() { /* From datasheet: 64 at 10bits. */ blackLevel_ = 4096; gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 512, -1, 512 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx214", CameraSensorHelperImx214) class CameraSensorHelperImx219 : public CameraSensorHelper { public: CameraSensorHelperImx219() { /* From datasheet: 64 at 10bits. */ blackLevel_ = 4096; gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 256, -1, 256 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx219", CameraSensorHelperImx219) class CameraSensorHelperImx258 : public CameraSensorHelper { public: CameraSensorHelperImx258() { /* From datasheet: 0x40 at 10bits. */ blackLevel_ = 4096; gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 512, -1, 512 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx258", CameraSensorHelperImx258) class CameraSensorHelperImx283 : public CameraSensorHelper { public: CameraSensorHelperImx283() { /* From datasheet: 0x32 at 10bits. */ blackLevel_ = 3200; gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 2048, -1, 2048 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx283", CameraSensorHelperImx283) 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 CameraSensorHelperImx327 : public CameraSensorHelperImx290 { }; REGISTER_CAMERA_SENSOR_HELPER("imx327", CameraSensorHelperImx327) class CameraSensorHelperImx335 : public CameraSensorHelper { public: CameraSensorHelperImx335() { /* From datasheet: 0x32 at 10bits. */ blackLevel_ = 3200; gainType_ = AnalogueGainExponential; gainConstants_.exp = { 1.0, expGainDb(0.3) }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx335", CameraSensorHelperImx335) class CameraSensorHelperImx415 : public CameraSensorHelper { public: CameraSensorHelperImx415() { gainType_ = AnalogueGainExponential; gainConstants_.exp = { 1.0, expGainDb(0.3) }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx415", CameraSensorHelperImx415) class CameraSensorHelperImx462 : public CameraSensorHelperImx290 { }; REGISTER_CAMERA_SENSOR_HELPER("imx462", CameraSensorHelperImx462) class CameraSensorHelperImx477 : public CameraSensorHelper { public: CameraSensorHelperImx477() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 0, 1024, -1, 1024 }; } }; REGISTER_CAMERA_SENSOR_HELPER("imx477", CameraSensorHelperImx477) class CameraSensorHelperOv2685 : public CameraSensorHelper { public: CameraSensorHelperOv2685() { /* * The Sensor Manual doesn't appear to document the gain model. * This has been validated with some empirical testing only. */ gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov2685", CameraSensorHelperOv2685) class CameraSensorHelperOv2740 : public CameraSensorHelper { public: CameraSensorHelperOv2740() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov2740", CameraSensorHelperOv2740) class CameraSensorHelperOv4689 : public CameraSensorHelper { public: CameraSensorHelperOv4689() { /* From datasheet: 0x40 at 12bits. */ blackLevel_ = 1024; gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov4689", CameraSensorHelperOv4689) class CameraSensorHelperOv5640 : public CameraSensorHelper { public: CameraSensorHelperOv5640() { /* From datasheet: 0x10 at 10bits. */ blackLevel_ = 1024; gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 16 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5640", CameraSensorHelperOv5640) class CameraSensorHelperOv5647 : public CameraSensorHelper { public: CameraSensorHelperOv5647() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 16 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov5647", CameraSensorHelperOv5647) 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() { /* From Linux kernel driver: 0x40 at 10bits. */ blackLevel_ = 4096; 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 CameraSensorHelperOv64a40 : public CameraSensorHelper { public: CameraSensorHelperOv64a40() { gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov64a40", CameraSensorHelperOv64a40) class CameraSensorHelperOv8858 : public CameraSensorHelper { public: CameraSensorHelperOv8858() { gainType_ = AnalogueGainLinear; /* * \todo Validate the selected 1/128 step value as it differs * from what the sensor manual describes. * * See: https://patchwork.linuxtv.org/project/linux-media/patch/20221106171129.166892-2-nicholas@rothemail.net/#142267 */ gainConstants_.linear = { 1, 0, 0, 128 }; } }; REGISTER_CAMERA_SENSOR_HELPER("ov8858", CameraSensorHelperOv8858) 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 */