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Diffstat (limited to 'src/ipa/rpi/controller/rpi/contrast.cpp')
| -rw-r--r-- | src/ipa/rpi/controller/rpi/contrast.cpp | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/src/ipa/rpi/controller/rpi/contrast.cpp b/src/ipa/rpi/controller/rpi/contrast.cpp new file mode 100644 index 00000000..bee1eadd --- /dev/null +++ b/src/ipa/rpi/controller/rpi/contrast.cpp @@ -0,0 +1,181 @@ +/* SPDX-License-Identifier: BSD-2-Clause */ +/* + * Copyright (C) 2019, Raspberry Pi Ltd + * + * contrast.cpp - contrast (gamma) control algorithm + */ +#include <stdint.h> + +#include <libcamera/base/log.h> + +#include "../contrast_status.h" +#include "../histogram.h" + +#include "contrast.h" + +using namespace RPiController; +using namespace libcamera; + +LOG_DEFINE_CATEGORY(RPiContrast) + +/* + * This is a very simple control algorithm which simply retrieves the results of + * AGC and AWB via their "status" metadata, and applies digital gain to the + * colour channels in accordance with those instructions. We take care never to + * apply less than unity gains, as that would cause fully saturated pixels to go + * off-white. + */ + +#define NAME "rpi.contrast" + +Contrast::Contrast(Controller *controller) + : ContrastAlgorithm(controller), brightness_(0.0), contrast_(1.0) +{ +} + +char const *Contrast::name() const +{ + return NAME; +} + +int Contrast::read(const libcamera::YamlObject ¶ms) +{ + // enable adaptive enhancement by default + config_.ceEnable = params["ce_enable"].get<int>(1); + // the point near the bottom of the histogram to move + config_.loHistogram = params["lo_histogram"].get<double>(0.01); + // where in the range to try and move it to + config_.loLevel = params["lo_level"].get<double>(0.015); + // but don't move by more than this + config_.loMax = params["lo_max"].get<double>(500); + // equivalent values for the top of the histogram... + config_.hiHistogram = params["hi_histogram"].get<double>(0.95); + config_.hiLevel = params["hi_level"].get<double>(0.95); + config_.hiMax = params["hi_max"].get<double>(2000); + return config_.gammaCurve.read(params["gamma_curve"]); +} + +void Contrast::setBrightness(double brightness) +{ + brightness_ = brightness; +} + +void Contrast::setContrast(double contrast) +{ + contrast_ = contrast; +} + +void Contrast::initialise() +{ + /* + * Fill in some default values as Prepare will run before Process gets + * called. + */ + status_.brightness = brightness_; + status_.contrast = contrast_; + status_.gammaCurve = config_.gammaCurve; +} + +void Contrast::prepare(Metadata *imageMetadata) +{ + imageMetadata->set("contrast.status", status_); +} + +Pwl computeStretchCurve(Histogram const &histogram, + ContrastConfig const &config) +{ + Pwl enhance; + enhance.append(0, 0); + /* + * If the start of the histogram is rather empty, try to pull it down a + * bit. + */ + double histLo = histogram.quantile(config.loHistogram) * + (65536 / histogram.bins()); + double levelLo = config.loLevel * 65536; + LOG(RPiContrast, Debug) + << "Move histogram point " << histLo << " to " << levelLo; + histLo = std::max(levelLo, + std::min(65535.0, std::min(histLo, levelLo + config.loMax))); + LOG(RPiContrast, Debug) + << "Final values " << histLo << " -> " << levelLo; + enhance.append(histLo, levelLo); + /* + * Keep the mid-point (median) in the same place, though, to limit the + * apparent amount of global brightness shift. + */ + double mid = histogram.quantile(0.5) * (65536 / histogram.bins()); + enhance.append(mid, mid); + + /* + * If the top to the histogram is empty, try to pull the pixel values + * there up. + */ + double histHi = histogram.quantile(config.hiHistogram) * + (65536 / histogram.bins()); + double levelHi = config.hiLevel * 65536; + LOG(RPiContrast, Debug) + << "Move histogram point " << histHi << " to " << levelHi; + histHi = std::min(levelHi, + std::max(0.0, std::max(histHi, levelHi - config.hiMax))); + LOG(RPiContrast, Debug) + << "Final values " << histHi << " -> " << levelHi; + enhance.append(histHi, levelHi); + enhance.append(65535, 65535); + return enhance; +} + +Pwl applyManualContrast(Pwl const &gammaCurve, double brightness, + double contrast) +{ + Pwl newGammaCurve; + LOG(RPiContrast, Debug) + << "Manual brightness " << brightness << " contrast " << contrast; + gammaCurve.map([&](double x, double y) { + newGammaCurve.append( + x, std::max(0.0, std::min(65535.0, + (y - 32768) * contrast + + 32768 + brightness))); + }); + return newGammaCurve; +} + +void Contrast::process(StatisticsPtr &stats, + [[maybe_unused]] Metadata *imageMetadata) +{ + Histogram &histogram = stats->yHist; + /* + * We look at the histogram and adjust the gamma curve in the following + * ways: 1. Adjust the gamma curve so as to pull the start of the + * histogram down, and possibly push the end up. + */ + Pwl gammaCurve = config_.gammaCurve; + if (config_.ceEnable) { + if (config_.loMax != 0 || config_.hiMax != 0) + gammaCurve = computeStretchCurve(histogram, config_).compose(gammaCurve); + /* + * We could apply other adjustments (e.g. partial equalisation) + * based on the histogram...? + */ + } + /* + * 2. Finally apply any manually selected brightness/contrast + * adjustment. + */ + if (brightness_ != 0 || contrast_ != 1.0) + gammaCurve = applyManualContrast(gammaCurve, brightness_, contrast_); + /* + * And fill in the status for output. Use more points towards the bottom + * of the curve. + */ + status_.brightness = brightness_; + status_.contrast = contrast_; + status_.gammaCurve = std::move(gammaCurve); +} + +/* Register algorithm with the system. */ +static Algorithm *create(Controller *controller) +{ + return (Algorithm *)new Contrast(controller); +} +static RegisterAlgorithm reg(NAME, &create); |