libcamera: ipa: Raspberry Pi IPA

Initial implementation of the Raspberry Pi (BCM2835) libcamera IPA and
associated libraries.

All code is licensed under the BSD-2-Clause terms.
Copyright (c) 2019-2020 Raspberry Pi Trading Ltd.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 178 insertions, 0 deletions

diff --git a/src/ipa/raspberrypi/controller/rpi/awb.hpp b/src/ipa/raspberrypi/controller/rpi/awb.hpp
new file mode 100644
index 00000000..36925252
--- /dev/null
+++ b/src/ipa/raspberrypi/controller/rpi/awb.hpp
@@ -0,0 +1,178 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi (Trading) Limited
+ *
+ * awb.hpp - AWB control algorithm
+ */
+#pragma once
+
+#include <mutex>
+#include <condition_variable>
+#include <thread>
+
+#include "../awb_algorithm.hpp"
+#include "../pwl.hpp"
+#include "../awb_status.h"
+
+namespace RPi {
+
+// Control algorithm to perform AWB calculations.
+
+struct AwbMode {
+	void Read(boost::property_tree::ptree const &params);
+	double ct_lo; // low CT value for search
+	double ct_hi; // high CT value for search
+};
+
+struct AwbPrior {
+	void Read(boost::property_tree::ptree const &params);
+	double lux; // lux level
+	Pwl prior; // maps CT to prior log likelihood for this lux level
+};
+
+struct AwbConfig {
+	AwbConfig() : default_mode(nullptr) {}
+	void Read(boost::property_tree::ptree const &params);
+	// Only repeat the AWB calculation every "this many" frames
+	uint16_t frame_period;
+	// number of initial frames for which speed taken as 1.0 (maximum)
+	uint16_t startup_frames;
+	double speed; // IIR filter speed applied to algorithm results
+	bool fast; // "fast" mode uses a 16x16 rather than 32x32 grid
+	Pwl ct_r; // function maps CT to r (= R/G)
+	Pwl ct_b; // function maps CT to b (= B/G)
+	// table of illuminant priors at different lux levels
+	std::vector<AwbPrior> priors;
+	// AWB "modes" (determines the search range)
+	std::map<std::string, AwbMode> modes;
+	AwbMode *default_mode; // mode used if no mode selected
+	// minimum proportion of pixels counted within AWB region for it to be
+	// "useful"
+	double min_pixels;
+	// minimum G value of those pixels, to be regarded a "useful"
+	uint16_t min_G;
+	// number of AWB regions that must be "useful" in order to do the AWB
+	// calculation
+	uint32_t min_regions;
+	// clamp on colour error term (so as not to penalise non-grey excessively)
+	double delta_limit;
+	// step size control in coarse search
+	double coarse_step;
+	// how far to wander off CT curve towards "more purple"
+	double transverse_pos;
+	// how far to wander off CT curve towards "more green"
+	double transverse_neg;
+	// red sensitivity ratio (set to canonical sensor's R/G divided by this
+	// sensor's R/G)
+	double sensitivity_r;
+	// blue sensitivity ratio (set to canonical sensor's B/G divided by this
+	// sensor's B/G)
+	double sensitivity_b;
+	// The whitepoint (which we normally "aim" for) can be moved.
+	double whitepoint_r;
+	double whitepoint_b;
+	bool bayes; // use Bayesian algorithm
+};
+
+class Awb : public AwbAlgorithm
+{
+public:
+	Awb(Controller *controller = NULL);
+	~Awb();
+	char const *Name() const override;
+	void Initialise() override;
+	void Read(boost::property_tree::ptree const &params) override;
+	void SetMode(std::string const &name) override;
+	void SetManualGains(double manual_r, double manual_b) override;
+	void Prepare(Metadata *image_metadata) override;
+	void Process(StatisticsPtr &stats, Metadata *image_metadata) override;
+	struct RGB {
+		RGB(double _R = INVALID, double _G = INVALID,
+		    double _B = INVALID)
+			: R(_R), G(_G), B(_B)
+		{
+		}
+		double R, G, B;
+		static const double INVALID;
+		bool Valid() const { return G != INVALID; }
+		bool Invalid() const { return G == INVALID; }
+		RGB &operator+=(RGB const &other)
+		{
+			R += other.R, G += other.G, B += other.B;
+			return *this;
+		}
+		RGB Square() const { return RGB(R * R, G * G, B * B); }
+	};
+
+private:
+	// configuration is read-only, and available to both threads
+	AwbConfig config_;
+	std::thread async_thread_;
+	void asyncFunc(); // asynchronous thread function
+	std::mutex mutex_;
+	// condvar for async thread to wait on
+	std::condition_variable async_signal_;
+	// condvar for synchronous thread to wait on
+	std::condition_variable sync_signal_;
+	// for sync thread to check  if async thread finished (requires mutex)
+	bool async_finished_;
+	// for async thread to check if it's been told to run (requires mutex)
+	bool async_start_;
+	// for async thread to check if it's been told to quit (requires mutex)
+	bool async_abort_;
+
+	// The following are only for the synchronous thread to use:
+	// for sync thread to note its has asked async thread to run
+	bool async_started_;
+	// counts up to frame_period before restarting the async thread
+	int frame_phase_;
+	int frame_count_; // counts up to startup_frames
+	int frame_count2_; // counts up to startup_frames for Process method
+	AwbStatus sync_results_;
+	AwbStatus prev_sync_results_;
+	std::string mode_name_;
+	std::mutex settings_mutex_;
+	// The following are for the asynchronous thread to use, though the main
+	// thread can set/reset them if the async thread is known to be idle:
+	void restartAsync(StatisticsPtr &stats, std::string const &mode_name,
+			  double lux);
+	// copy out the results from the async thread so that it can be restarted
+	void fetchAsyncResults();
+	StatisticsPtr statistics_;
+	AwbMode *mode_;
+	double lux_;
+	AwbStatus async_results_;
+	void doAwb();
+	void awbBayes();
+	void awbGrey();
+	void prepareStats();
+	double computeDelta2Sum(double gain_r, double gain_b);
+	Pwl interpolatePrior();
+	double coarseSearch(Pwl const &prior);
+	void fineSearch(double &t, double &r, double &b, Pwl const &prior);
+	std::vector<RGB> zones_;
+	std::vector<Pwl::Point> points_;
+	// manual r setting
+	double manual_r_;
+	// manual b setting
+	double manual_b_;
+};
+
+static inline Awb::RGB operator+(Awb::RGB const &a, Awb::RGB const &b)
+{
+	return Awb::RGB(a.R + b.R, a.G + b.G, a.B + b.B);
+}
+static inline Awb::RGB operator-(Awb::RGB const &a, Awb::RGB const &b)
+{
+	return Awb::RGB(a.R - b.R, a.G - b.G, a.B - b.B);
+}
+static inline Awb::RGB operator*(double d, Awb::RGB const &rgb)
+{
+	return Awb::RGB(d * rgb.R, d * rgb.G, d * rgb.B);
+}
+static inline Awb::RGB operator*(Awb::RGB const &rgb, double d)
+{
+	return d * rgb;
+}
+
+} // namespace RPi