Naushir Patuck
226792a141
Under the right circumstances, the alsc calculations could spread the colour errors across the entire image as lambda remains unbound. This would cause the corrected image chroma values to slowly drift to incorrect values. This change adds a config parameter (alsc.lambda_bound) that provides an upper and lower bound to the lambda value at every stage of the calculation. With this change, we now adjust the lambda values so that the average across the entire grid is 1 instead of normalising to the minimum value. Signed-off-by: Naushir Patuck <naush@raspberrypi.com> Reviewed-by: David Plowman <david.plowman@raspberrypi.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Tested-by: Naushir Patuck <naush@raspberrypi.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
107 lines
3.5 KiB
C++
107 lines
3.5 KiB
C++
/* SPDX-License-Identifier: BSD-2-Clause */
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/*
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* Copyright (C) 2019, Raspberry Pi (Trading) Limited
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*
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* alsc.hpp - ALSC (auto lens shading correction) control algorithm
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*/
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#pragma once
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#include <mutex>
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#include <condition_variable>
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#include <thread>
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#include "../algorithm.hpp"
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#include "../alsc_status.h"
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namespace RPiController {
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// Algorithm to generate automagic LSC (Lens Shading Correction) tables.
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struct AlscCalibration {
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double ct;
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double table[ALSC_CELLS_X * ALSC_CELLS_Y];
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};
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struct AlscConfig {
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// Only repeat the ALSC calculation every "this many" frames
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uint16_t frame_period;
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// number of initial frames for which speed taken as 1.0 (maximum)
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uint16_t startup_frames;
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// IIR filter speed applied to algorithm results
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double speed;
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double sigma_Cr;
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double sigma_Cb;
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double min_count;
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uint16_t min_G;
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double omega;
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uint32_t n_iter;
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double luminance_lut[ALSC_CELLS_X * ALSC_CELLS_Y];
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double luminance_strength;
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std::vector<AlscCalibration> calibrations_Cr;
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std::vector<AlscCalibration> calibrations_Cb;
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double default_ct; // colour temperature if no metadata found
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double threshold; // iteration termination threshold
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double lambda_bound; // upper/lower bound for lambda from a value of 1
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};
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class Alsc : public Algorithm
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{
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public:
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Alsc(Controller *controller = NULL);
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~Alsc();
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char const *Name() const override;
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void Initialise() override;
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void SwitchMode(CameraMode const &camera_mode, Metadata *metadata) override;
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void Read(boost::property_tree::ptree const ¶ms) override;
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void Prepare(Metadata *image_metadata) override;
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void Process(StatisticsPtr &stats, Metadata *image_metadata) override;
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private:
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// configuration is read-only, and available to both threads
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AlscConfig config_;
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bool first_time_;
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CameraMode camera_mode_;
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double luminance_table_[ALSC_CELLS_X * ALSC_CELLS_Y];
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std::thread async_thread_;
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void asyncFunc(); // asynchronous thread function
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std::mutex mutex_;
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// condvar for async thread to wait on
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std::condition_variable async_signal_;
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// condvar for synchronous thread to wait on
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std::condition_variable sync_signal_;
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// for sync thread to check if async thread finished (requires mutex)
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bool async_finished_;
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// for async thread to check if it's been told to run (requires mutex)
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bool async_start_;
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// for async thread to check if it's been told to quit (requires mutex)
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bool async_abort_;
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// The following are only for the synchronous thread to use:
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// for sync thread to note its has asked async thread to run
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bool async_started_;
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// counts up to frame_period before restarting the async thread
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int frame_phase_;
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// counts up to startup_frames
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int frame_count_;
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// counts up to startup_frames for Process function
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int frame_count2_;
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double sync_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
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double prev_sync_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
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void waitForAysncThread();
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// The following are for the asynchronous thread to use, though the main
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// thread can set/reset them if the async thread is known to be idle:
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void restartAsync(StatisticsPtr &stats, Metadata *image_metadata);
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// copy out the results from the async thread so that it can be restarted
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void fetchAsyncResults();
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double ct_;
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bcm2835_isp_stats_region statistics_[ALSC_CELLS_Y * ALSC_CELLS_X];
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double async_results_[3][ALSC_CELLS_Y][ALSC_CELLS_X];
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double async_lambda_r_[ALSC_CELLS_X * ALSC_CELLS_Y];
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double async_lambda_b_[ALSC_CELLS_X * ALSC_CELLS_Y];
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void doAlsc();
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double lambda_r_[ALSC_CELLS_X * ALSC_CELLS_Y];
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double lambda_b_[ALSC_CELLS_X * ALSC_CELLS_Y];
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};
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} // namespace RPiController
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