kwin/autotests/test_colorspaces.cpp

/*
    SPDX-FileCopyrightText: 2023 Xaver Hugl <xaver.hugl@gmail.com>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include <QTest>

#include "core/colorpipeline.h"
#include "core/colorspace.h"

using namespace KWin;

class TestColorspaces : public QObject
{
    Q_OBJECT

public:
    TestColorspaces() = default;

private Q_SLOTS:
    void roundtripConversion_data();
    void roundtripConversion();
    void nonNormalizedPrimaries();
    void testIdentityTransformation_data();
    void testIdentityTransformation();
    void testColorPipeline_data();
    void testColorPipeline();
};

static bool compareVectors(const QVector3D &one, const QVector3D &two, float maxDifference)
{
    const bool ret = std::abs(one.x() - two.x()) <= maxDifference
        && std::abs(one.y() - two.y()) <= maxDifference
        && std::abs(one.z() - two.z()) <= maxDifference;
    if (!ret) {
        qWarning() << one << "!=" << two << "within" << maxDifference;
    }
    return ret;
}

static const double s_resolution10bit = std::pow(1.0 / 2.0, 10);

void TestColorspaces::roundtripConversion_data()
{
    QTest::addColumn<NamedColorimetry>("srcColorimetry");
    QTest::addColumn<TransferFunction::Type>("srcTransferFunction");
    QTest::addColumn<NamedColorimetry>("dstColorimetry");
    QTest::addColumn<TransferFunction::Type>("dstTransferFunction");
    QTest::addColumn<double>("requiredAccuracy");

    QTest::addRow("BT709 (sRGB) <-> BT2020 (linear)") << NamedColorimetry::BT709 << TransferFunction::sRGB << NamedColorimetry::BT2020 << TransferFunction::linear << s_resolution10bit;
    QTest::addRow("BT709 (gamma 2.2) <-> BT2020 (linear)") << NamedColorimetry::BT709 << TransferFunction::gamma22 << NamedColorimetry::BT2020 << TransferFunction::linear << s_resolution10bit;
    QTest::addRow("BT709 (linear) <-> BT2020 (linear)") << NamedColorimetry::BT709 << TransferFunction::linear << NamedColorimetry::BT2020 << TransferFunction::linear << s_resolution10bit;
    QTest::addRow("BT709 (PQ) <-> BT2020 (linear)") << NamedColorimetry::BT709 << TransferFunction::PerceptualQuantizer << NamedColorimetry::BT2020 << TransferFunction::linear << 3 * s_resolution10bit;
}

void TestColorspaces::roundtripConversion()
{
    QFETCH(NamedColorimetry, srcColorimetry);
    QFETCH(TransferFunction::Type, srcTransferFunction);
    QFETCH(NamedColorimetry, dstColorimetry);
    QFETCH(TransferFunction::Type, dstTransferFunction);
    QFETCH(double, requiredAccuracy);

    const auto src = ColorDescription(srcColorimetry, TransferFunction(srcTransferFunction), 100, 0, 100, 100);
    const auto dst = ColorDescription(dstColorimetry, TransferFunction(dstTransferFunction), 100, 0, 100, 100);

    const QVector3D red(1, 0, 0);
    const QVector3D green(0, 1, 0);
    const QVector3D blue(0, 0, 1);
    const QVector3D white(1, 1, 1);
    constexpr std::array renderingIntents = {
        RenderingIntent::RelativeColorimetric,
        RenderingIntent::AbsoluteColorimetric,
    };
    for (const RenderingIntent intent : renderingIntents) {
        QVERIFY(compareVectors(dst.mapTo(src.mapTo(red, dst, intent), src, intent), red, requiredAccuracy));
        QVERIFY(compareVectors(dst.mapTo(src.mapTo(green, dst, intent), src, intent), green, requiredAccuracy));
        QVERIFY(compareVectors(dst.mapTo(src.mapTo(blue, dst, intent), src, intent), blue, requiredAccuracy));
        QVERIFY(compareVectors(dst.mapTo(src.mapTo(white, dst, intent), src, intent), white, requiredAccuracy));
    }
}

void TestColorspaces::nonNormalizedPrimaries()
{
    // this test ensures that non-normalized primaries don't mess up the transformations between color spaces
    const auto &from = ColorDescription::sRGB;
    const ColorDescription to(Colorimetry(Colorimetry::xyToXYZ(from.containerColorimetry().red()) * 2, Colorimetry::xyToXYZ(from.containerColorimetry().green()) * 2, Colorimetry::xyToXYZ(from.containerColorimetry().blue()) * 2, Colorimetry::xyToXYZ(from.containerColorimetry().white()) * 2), from.transferFunction(), from.referenceLuminance(), from.minLuminance(), from.maxAverageLuminance(), from.maxHdrLuminance());

    const auto convertedWhite = from.toOther(to, RenderingIntent::RelativeColorimetric) * QVector3D(1, 1, 1);
    QCOMPARE_LE(std::abs(1 - convertedWhite.x()), s_resolution10bit);
    QCOMPARE_LE(std::abs(1 - convertedWhite.y()), s_resolution10bit);
    QCOMPARE_LE(std::abs(1 - convertedWhite.z()), s_resolution10bit);
}

void TestColorspaces::testIdentityTransformation_data()
{
    QTest::addColumn<NamedColorimetry>("colorimetry");
    QTest::addColumn<TransferFunction::Type>("transferFunction");

    QTest::addRow("BT709 (sRGB)") << NamedColorimetry::BT709 << TransferFunction::sRGB;
    QTest::addRow("BT709 (gamma22)") << NamedColorimetry::BT709 << TransferFunction::gamma22;
    QTest::addRow("BT709 (PQ)") << NamedColorimetry::BT709 << TransferFunction::PerceptualQuantizer;
    QTest::addRow("BT709 (linear)") << NamedColorimetry::BT709 << TransferFunction::linear;
    QTest::addRow("BT2020 (sRGB)") << NamedColorimetry::BT2020 << TransferFunction::sRGB;
    QTest::addRow("BT2020 (gamma22)") << NamedColorimetry::BT2020 << TransferFunction::gamma22;
    QTest::addRow("BT2020 (PQ)") << NamedColorimetry::BT2020 << TransferFunction::PerceptualQuantizer;
    QTest::addRow("BT2020 (linear)") << NamedColorimetry::BT2020 << TransferFunction::linear;
}

void TestColorspaces::testIdentityTransformation()
{
    QFETCH(NamedColorimetry, colorimetry);
    QFETCH(TransferFunction::Type, transferFunction);
    const ColorDescription color(colorimetry, TransferFunction(transferFunction), 100, 0, 100, 100);

    constexpr std::array renderingIntents = {
        RenderingIntent::Perceptual,
        RenderingIntent::RelativeColorimetric,
        RenderingIntent::AbsoluteColorimetric,
    };
    for (const RenderingIntent intent : renderingIntents) {
        const auto pipeline = ColorPipeline::create(color, color, intent);
        if (!pipeline.isIdentity()) {
            qWarning() << pipeline;
        }
        QVERIFY(pipeline.isIdentity());
    }
}

void TestColorspaces::testColorPipeline_data()
{
    QTest::addColumn<ColorDescription>("srcColor");
    QTest::addColumn<ColorDescription>("dstColor");
    QTest::addColumn<QVector3D>("dstBlack");
    QTest::addColumn<QVector3D>("dstGray");
    QTest::addColumn<QVector3D>("dstWhite");
    QTest::addColumn<RenderingIntent>("intent");

    QTest::addRow("sRGB -> rec.2020 relative colorimetric")
        << ColorDescription(NamedColorimetry::BT709, TransferFunction(TransferFunction::gamma22), TransferFunction::defaultReferenceLuminanceFor(TransferFunction::gamma22), 0, std::nullopt, std::nullopt)
        << ColorDescription(NamedColorimetry::BT2020, TransferFunction(TransferFunction::PerceptualQuantizer), 500, 0, std::nullopt, std::nullopt)
        << QVector3D(0.044, 0.044, 0.044)
        << QVector3D(0.517, 0.517, 0.517)
        << QVector3D(0.677, 0.677, 0.677)
        << RenderingIntent::RelativeColorimetric;
    QTest::addRow("sRGB -> scRGB relative colorimetric")
        << ColorDescription(NamedColorimetry::BT709, TransferFunction(TransferFunction::gamma22), TransferFunction::defaultReferenceLuminanceFor(TransferFunction::gamma22), 0, std::nullopt, std::nullopt)
        << ColorDescription(NamedColorimetry::BT709, TransferFunction(TransferFunction::linear, 0, 80), 80, 0, std::nullopt, std::nullopt)
        << QVector3D(0.0001, 0.0001, 0.0001)
        << QVector3D(0.2177376408240310, 0.2177376408240310, 0.2177376408240310)
        << QVector3D(1, 1, 1)
        << RenderingIntent::RelativeColorimetric;
}

void TestColorspaces::testColorPipeline()
{
    QFETCH(ColorDescription, srcColor);
    QFETCH(ColorDescription, dstColor);
    QFETCH(QVector3D, dstBlack);
    QFETCH(QVector3D, dstGray);
    QFETCH(QVector3D, dstWhite);
    QFETCH(RenderingIntent, intent);

    const auto pipeline = ColorPipeline::create(srcColor, dstColor, intent);
    QVERIFY(compareVectors(pipeline.evaluate(QVector3D(0, 0, 0)), dstBlack, s_resolution10bit));
    QVERIFY(compareVectors(pipeline.evaluate(QVector3D(0.5, 0.5, 0.5)), dstGray, s_resolution10bit));
    QVERIFY(compareVectors(pipeline.evaluate(QVector3D(1, 1, 1)), dstWhite, s_resolution10bit));

    const auto inversePipeline = ColorPipeline::create(dstColor, srcColor, intent);
    QVERIFY(compareVectors(inversePipeline.evaluate(dstBlack), QVector3D(0, 0, 0), s_resolution10bit));
    QVERIFY(compareVectors(inversePipeline.evaluate(dstGray), QVector3D(0.5, 0.5, 0.5), s_resolution10bit));
    QVERIFY(compareVectors(inversePipeline.evaluate(dstWhite), QVector3D(1, 1, 1), s_resolution10bit));
}

QTEST_MAIN(TestColorspaces)

#include "test_colorspaces.moc"