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-rw-r--r--src/ipa/simple/black_level.cpp88
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diff --git a/src/ipa/simple/black_level.cpp b/src/ipa/simple/black_level.cpp
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-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-/*
- * Copyright (C) 2024, Red Hat Inc.
- *
- * black level handling
- */
-
-#include "black_level.h"
-
-#include <numeric>
-
-#include <libcamera/base/log.h>
-
-namespace libcamera {
-
-LOG_DEFINE_CATEGORY(IPASoftBL)
-
-/**
- * \class BlackLevel
- * \brief Object providing black point level for software ISP
- *
- * Black level can be provided in hardware tuning files or, if no tuning file is
- * available for the given hardware, guessed automatically, with less accuracy.
- * As tuning files are not yet implemented for software ISP, BlackLevel
- * currently provides only guessed black levels.
- *
- * This class serves for tracking black level as a property of the underlying
- * hardware, not as means of enhancing a particular scene or image.
- *
- * The class is supposed to be instantiated for the given camera stream.
- * The black level can be retrieved using BlackLevel::get() method. It is
- * initially 0 and may change when updated using BlackLevel::update() method.
- */
-
-BlackLevel::BlackLevel()
- : blackLevel_(255), blackLevelSet_(false)
-{
-}
-
-/**
- * \brief Return the current black level
- *
- * \return The black level, in the range from 0 (minimum) to 255 (maximum).
- * If the black level couldn't be determined yet, return 0.
- */
-uint8_t BlackLevel::get() const
-{
- return blackLevelSet_ ? blackLevel_ : 0;
-}
-
-/**
- * \brief Update black level from the provided histogram
- * \param[in] yHistogram The histogram to be used for updating black level
- *
- * The black level is property of the given hardware, not image. It is updated
- * only if it has not been yet set or if it is lower than the lowest value seen
- * so far.
- */
-void BlackLevel::update(SwIspStats::Histogram &yHistogram)
-{
- /*
- * The constant is selected to be "good enough", not overly conservative or
- * aggressive. There is no magic about the given value.
- */
- constexpr float ignoredPercentage_ = 0.02;
- const unsigned int total =
- std::accumulate(begin(yHistogram), end(yHistogram), 0);
- const unsigned int pixelThreshold = ignoredPercentage_ * total;
- const unsigned int histogramRatio = 256 / SwIspStats::kYHistogramSize;
- const unsigned int currentBlackIdx = blackLevel_ / histogramRatio;
-
- for (unsigned int i = 0, seen = 0;
- i < currentBlackIdx && i < SwIspStats::kYHistogramSize;
- i++) {
- seen += yHistogram[i];
- if (seen >= pixelThreshold) {
- blackLevel_ = i * histogramRatio;
- blackLevelSet_ = true;
- LOG(IPASoftBL, Debug)
- << "Auto-set black level: "
- << i << "/" << SwIspStats::kYHistogramSize
- << " (" << 100 * (seen - yHistogram[i]) / total << "% below, "
- << 100 * seen / total << "% at or below)";
- break;
- }
- };
-}
-} /* namespace libcamera */