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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2024, Red Hat Inc.
*
* Black level handling
*/
#include "blc.h"
#include <numeric>
#include <libcamera/base/log.h>
namespace libcamera {
namespace ipa::soft::algorithms {
LOG_DEFINE_CATEGORY(IPASoftBL)
BlackLevel::BlackLevel()
{
}
int BlackLevel::configure(IPAContext &context,
[[maybe_unused]] const IPAConfigInfo &configInfo)
{
context.activeState.blc.level =
context.configuration.black.level.value_or(255);
return 0;
}
void BlackLevel::process(IPAContext &context,
[[maybe_unused]] const uint32_t frame,
IPAFrameContext &frameContext,
const SwIspStats *stats,
[[maybe_unused]] ControlList &metadata)
{
if (context.configuration.black.level.has_value())
return;
if (frameContext.sensor.exposure == exposure_ &&
frameContext.sensor.gain == gain_) {
return;
}
const SwIspStats::Histogram &histogram = stats->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(histogram), end(histogram), 0);
const unsigned int pixelThreshold = ignoredPercentage * total;
const unsigned int histogramRatio = 256 / SwIspStats::kYHistogramSize;
const unsigned int currentBlackIdx =
context.activeState.blc.level / histogramRatio;
for (unsigned int i = 0, seen = 0;
i < currentBlackIdx && i < SwIspStats::kYHistogramSize;
i++) {
seen += histogram[i];
if (seen >= pixelThreshold) {
context.activeState.blc.level = i * histogramRatio;
exposure_ = frameContext.sensor.exposure;
gain_ = frameContext.sensor.gain;
LOG(IPASoftBL, Debug)
<< "Auto-set black level: "
<< i << "/" << SwIspStats::kYHistogramSize
<< " (" << 100 * (seen - histogram[i]) / total << "% below, "
<< 100 * seen / total << "% at or below)";
break;
}
};
}
REGISTER_IPA_ALGORITHM(BlackLevel, "BlackLevel")
} /* namespace ipa::soft::algorithms */
} /* namespace libcamera */
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