/* 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 = 255; return 0; } void BlackLevel::process(IPAContext &context, [[maybe_unused]] const uint32_t frame, [[maybe_unused]] IPAFrameContext &frameContext, const SwIspStats *stats, [[maybe_unused]] ControlList &metadata) { 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; 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 */