diff options
Diffstat (limited to 'src/ipa/libipa')
| -rw-r--r-- | src/ipa/libipa/camera_sensor_helper.cpp | 98 | ||||
| -rw-r--r-- | src/ipa/libipa/camera_sensor_helper.h | 3 |
2 files changed, 99 insertions, 2 deletions
diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp index a1339c83..ffc7c1d7 100644 --- a/src/ipa/libipa/camera_sensor_helper.cpp +++ b/src/ipa/libipa/camera_sensor_helper.cpp @@ -8,6 +8,7 @@ #include "camera_sensor_helper.h" #include <cmath> +#include <limits> #include <libcamera/base/log.h> @@ -40,6 +41,7 @@ namespace ipa { */ /** + * \fn CameraSensorHelper::CameraSensorHelper() * \brief Construct a CameraSensorHelper instance * * CameraSensorHelper derived class instances shall never be constructed @@ -234,6 +236,7 @@ double CameraSensorHelper::gain(uint32_t gainCode) const /** * \var CameraSensorHelper::blackLevel_ * \brief The black level of the sensor + * \sa CameraSensorHelper::blackLevel() */ /** @@ -398,6 +401,99 @@ static constexpr double expGainDb(double step) 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<decltype(m)>::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: @@ -601,6 +697,8 @@ class CameraSensorHelperOv5675 : public CameraSensorHelper public: CameraSensorHelperOv5675() { + /* From Linux kernel driver: 0x40 at 10bits. */ + blackLevel_ = 4096; gainType_ = AnalogueGainLinear; gainConstants_.linear = { 1, 0, 0, 128 }; } diff --git a/src/ipa/libipa/camera_sensor_helper.h b/src/ipa/libipa/camera_sensor_helper.h index ac276e27..75868205 100644 --- a/src/ipa/libipa/camera_sensor_helper.h +++ b/src/ipa/libipa/camera_sensor_helper.h @@ -7,10 +7,9 @@ #pragma once -#include <stdint.h> - #include <memory> #include <optional> +#include <stdint.h> #include <string> #include <vector> |