8c84efa486
It's more natural to represent color gains as floating point numbers rather than using a particular pixel-related representation. double is used rather than float because it's a more common floating point type in libcamera algorithms. Otherwise there is no obvious reason to select one over the other here. The constructed color tables still use integer representation for efficiency. Black level still uses pixel (integer) values, for consistency with other libcamera parts. Signed-off-by: Milan Zamazal <mzamazal@redhat.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Umang Jain <umang.jain@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
70 lines
1.8 KiB
C++
70 lines
1.8 KiB
C++
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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/*
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* Copyright (C) 2024, Red Hat Inc.
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*
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* Auto white balance
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*/
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#include "awb.h"
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#include <numeric>
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#include <stdint.h>
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#include <libcamera/base/log.h>
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#include "simple/ipa_context.h"
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namespace libcamera {
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LOG_DEFINE_CATEGORY(IPASoftAwb)
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namespace ipa::soft::algorithms {
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int Awb::configure(IPAContext &context,
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[[maybe_unused]] const IPAConfigInfo &configInfo)
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{
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auto &gains = context.activeState.gains;
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gains.red = gains.green = gains.blue = 1.0;
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return 0;
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}
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void Awb::process(IPAContext &context,
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[[maybe_unused]] const uint32_t frame,
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[[maybe_unused]] IPAFrameContext &frameContext,
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const SwIspStats *stats,
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[[maybe_unused]] ControlList &metadata)
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{
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const SwIspStats::Histogram &histogram = stats->yHistogram;
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const uint8_t blackLevel = context.activeState.blc.level;
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/*
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* Black level must be subtracted to get the correct AWB ratios, they
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* would be off if they were computed from the whole brightness range
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* rather than from the sensor range.
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*/
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const uint64_t nPixels = std::accumulate(
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histogram.begin(), histogram.end(), 0);
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const uint64_t offset = blackLevel * nPixels;
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const uint64_t sumR = stats->sumR_ - offset / 4;
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const uint64_t sumG = stats->sumG_ - offset / 2;
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const uint64_t sumB = stats->sumB_ - offset / 4;
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/*
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* Calculate red and blue gains for AWB.
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* Clamp max gain at 4.0, this also avoids 0 division.
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*/
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auto &gains = context.activeState.gains;
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gains.red = sumR <= sumG / 4 ? 4.0 : static_cast<double>(sumG) / sumR;
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gains.blue = sumB <= sumG / 4 ? 4.0 : static_cast<double>(sumG) / sumB;
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/* Green gain is fixed to 1.0 */
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LOG(IPASoftAwb, Debug) << "gain R/B " << gains.red << "/" << gains.blue;
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}
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REGISTER_IPA_ALGORITHM(Awb, "Awb")
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} /* namespace ipa::soft::algorithms */
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} /* namespace libcamera */
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