127bc20965
Fix the top-level file description to mention the file contains an AWB grey world implementation, not a base class, and fix a grammar mistake in a documentation block. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>
114 lines
3.1 KiB
C++
114 lines
3.1 KiB
C++
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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/*
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* Copyright (C) 2024 Ideas on Board Oy
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*
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* Implementation of grey world AWB algorithm
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*/
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#include "awb_grey.h"
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#include <algorithm>
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#include <libcamera/base/log.h>
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#include <libcamera/control_ids.h>
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#include "colours.h"
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using namespace libcamera::controls;
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/**
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* \file awb_grey.h
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* \brief Implementation of a grey world AWB algorithm
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*/
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namespace libcamera {
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LOG_DECLARE_CATEGORY(Awb)
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namespace ipa {
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/**
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* \class AwbGrey
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* \brief A Grey world auto white balance algorithm
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*/
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/**
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* \brief Initialize the algorithm with the given tuning data
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* \param[in] tuningData The tuning data for the algorithm
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*
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* Load the colour temperature curve from the tuning data. If there is no tuning
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* data available, continue with a warning. Manual colour temperature will not
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* work in that case.
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*
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* \return 0 on success, a negative error code otherwise
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*/
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int AwbGrey::init(const YamlObject &tuningData)
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{
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Interpolator<Vector<double, 2>> gains;
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int ret = gains.readYaml(tuningData["colourGains"], "ct", "gains");
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if (ret < 0)
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LOG(Awb, Warning)
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<< "Failed to parse 'colourGains' "
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<< "parameter from tuning file; "
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<< "manual colour temperature will not work properly";
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else
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colourGainCurve_ = gains;
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return 0;
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}
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/**
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* \brief Calculate AWB data from the given statistics
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* \param[in] stats The statistics to use for the calculation
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* \param[in] lux The lux value of the scene
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*
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* The colour temperature is estimated based on the colours::estimateCCT()
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* function. The gains are calculated purely based on the RGB means provided by
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* the \a stats. The colour temperature is not taken into account when
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* calculating the gains.
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*
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* The \a lux parameter is not used in this algorithm.
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*
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* \return The AWB result
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*/
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AwbResult AwbGrey::calculateAwb(const AwbStats &stats, [[maybe_unused]] unsigned int lux)
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{
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AwbResult result;
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auto means = stats.rgbMeans();
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result.colourTemperature = estimateCCT(means);
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/*
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* Estimate the red and blue gains to apply in a grey world. The green
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* gain is hardcoded to 1.0. Avoid divisions by zero by clamping the
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* divisor to a minimum value of 1.0.
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*/
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result.gains.r() = means.g() / std::max(means.r(), 1.0);
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result.gains.g() = 1.0;
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result.gains.b() = means.g() / std::max(means.b(), 1.0);
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return result;
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}
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/**
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* \brief Compute white balance gains from a colour temperature
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* \param[in] colourTemperature The colour temperature in Kelvin
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*
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* Compute the white balance gains from a \a colourTemperature. This function
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* does not take any statistics into account. It simply interpolates the colour
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* gains configured in the colour temperature curve.
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*
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* \return The colour gains if a colour temperature curve is available,
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* [1, 1, 1] otherwise.
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*/
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RGB<double> AwbGrey::gainsFromColourTemperature(double colourTemperature)
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{
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if (!colourGainCurve_) {
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LOG(Awb, Error) << "No gains defined";
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return RGB<double>({ 1.0, 1.0, 1.0 });
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}
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auto gains = colourGainCurve_->getInterpolated(colourTemperature);
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return { { gains[0], 1.0, gains[1] } };
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}
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} /* namespace ipa */
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} /* namespace libcamera */
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