Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit eedb69ab authored by Romain Guy's avatar Romain Guy
Browse files

Add ColorSpace::createLUT 

Generates a 3D LUT of a specified size. The generated LUT is meant to
be used as a 3D OpenGL texture for fast color space conversions in
shaders. This will be used to convert from P3 bitmaps to scRGB.

Bug: 32984164
Test: colorspace_test
Change-Id: I01f7276f885c71bde480e79260013d62786b377c
parent 3d9da20a

include/ui/ColorSpace.h

+14 −0
Original line number Diff line number Diff line
@@ -180,6 +180,11 @@ public: 
            return apply(mDestination.fromLinear(mTransform * linear), mDestination.getClamper());

        }



        constexpr float3 transformLinear(const float3& v) const noexcept {

            float3 linear = apply(v, mSource.getClamper());

            return apply(mTransform * linear, mDestination.getClamper());

        }



    private:

        const ColorSpace& mSource;

        const ColorSpace& mDestination;
@@ -190,6 +195,15 @@ public: 
        return Connector(src, dst);

    }



    // Creates a NxNxN 3D LUT, where N is the specified size (min=2, max=256)

    // The 3D lookup coordinates map to the RGB components: u=R, v=G, w=B

    // The generated 3D LUT is meant to be used as a 3D texture and its Y

    // axis is thus already flipped

    // The source color space must define its values in the domain [0..1]

    // The generated LUT transforms from gamma space to gamma space

    static std::unique_ptr<float3> createLUT(uint32_t size,

            const ColorSpace& src, const ColorSpace& dst);



private:

    static constexpr mat3 computeXYZMatrix(

            const std::array<float2, 3>& primaries, const float2& whitePoint);

include/ui/TVecHelpers.h

+6 −6
Original line number Diff line number Diff line
@@ -324,7 +324,7 @@ public: 


    template<typename RT>

    friend inline

    constexpr VECTOR<bool> PURE equal(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

    CONSTEXPR VECTOR<bool> PURE equal(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

        VECTOR<bool> r;

        for (size_t i = 0; i < lv.size(); i++) {

            r[i] = lv[i] == rv[i];
@@ -334,7 +334,7 @@ public: 


    template<typename RT>

    friend inline

    constexpr VECTOR<bool> PURE notEqual(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

    CONSTEXPR VECTOR<bool> PURE notEqual(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

        VECTOR<bool> r;

        for (size_t i = 0; i < lv.size(); i++) {

            r[i] = lv[i] != rv[i];
@@ -344,7 +344,7 @@ public: 


    template<typename RT>

    friend inline

    constexpr VECTOR<bool> PURE lessThan(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

    CONSTEXPR VECTOR<bool> PURE lessThan(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

        VECTOR<bool> r;

        for (size_t i = 0; i < lv.size(); i++) {

            r[i] = lv[i] < rv[i];
@@ -354,7 +354,7 @@ public: 


    template<typename RT>

    friend inline

    constexpr VECTOR<bool> PURE lessThanEqual(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

    CONSTEXPR VECTOR<bool> PURE lessThanEqual(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

        VECTOR<bool> r;

        for (size_t i = 0; i < lv.size(); i++) {

            r[i] = lv[i] <= rv[i];
@@ -364,7 +364,7 @@ public: 


    template<typename RT>

    friend inline

    constexpr VECTOR<bool> PURE greaterThan(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

    CONSTEXPR VECTOR<bool> PURE greaterThan(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

        VECTOR<bool> r;

        for (size_t i = 0; i < lv.size(); i++) {

            r[i] = lv[i] > rv[i];
@@ -374,7 +374,7 @@ public: 


    template<typename RT>

    friend inline

    constexpr VECTOR<bool> PURE greaterThanEqual(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

    CONSTEXPR VECTOR<bool> PURE greaterThanEqual(const VECTOR<T>& lv, const VECTOR<RT>& rv) {

        VECTOR<bool> r;

        for (size_t i = 0; i < lv.size(); i++) {

            r[i] = lv[i] >= rv[i];

libs/ui/ColorSpace.cpp

+64 −41
Original line number Diff line number Diff line
@@ -96,47 +96,6 @@ constexpr mat3 ColorSpace::computeXYZMatrix( 
    };

}



static const float2 ILLUMINANT_D50_XY = {0.34567f, 0.35850f};

static const float3 ILLUMINANT_D50_XYZ = {0.964212f, 1.0f, 0.825188f};

static const mat3 VON_KRIES = mat3{

    float3{ 0.8951f, -0.7502f,  0.0389f},

    float3{ 0.2664f,  1.7135f, -0.0685f},

    float3{-0.1614f,  0.0367f,  1.0296f}

};



static mat3 adaptation(const mat3& matrix, const float3& srcWhitePoint, const float3& dstWhitePoint) {

    float3 srcLMS = matrix * srcWhitePoint;

    float3 dstLMS = matrix * dstWhitePoint;

    return inverse(matrix) * mat3{dstLMS / srcLMS} * matrix;

}



ColorSpace::Connector::Connector(

        const ColorSpace& src,

        const ColorSpace& dst) noexcept

        : mSource(src)

        , mDestination(dst) {



    if (all(lessThan(abs(src.getWhitePoint() - dst.getWhitePoint()), float2{1e-3f}))) {

        mTransform = dst.getXYZtoRGB() * src.getRGBtoXYZ();

    } else {

        mat3 rgbToXYZ(src.getRGBtoXYZ());

        mat3 xyzToRGB(dst.getXYZtoRGB());



        float3 srcXYZ = XYZ(float3{src.getWhitePoint(), 1});

        float3 dstXYZ = XYZ(float3{dst.getWhitePoint(), 1});



        if (any(greaterThan(abs(src.getWhitePoint() - ILLUMINANT_D50_XY), float2{1e-3f}))) {

            rgbToXYZ = adaptation(VON_KRIES, srcXYZ, ILLUMINANT_D50_XYZ) * src.getRGBtoXYZ();

        }



        if (any(greaterThan(abs(dst.getWhitePoint() - ILLUMINANT_D50_XY), float2{1e-3f}))) {

            xyzToRGB = inverse(adaptation(VON_KRIES, dstXYZ, ILLUMINANT_D50_XYZ) * dst.getRGBtoXYZ());

        }



        mTransform = xyzToRGB * rgbToXYZ;

    }

}



static constexpr float rcpResponse(float x, float g,float a, float b, float c, float d) {

    return x >= d * c ? (std::pow(x, 1.0f / g) - b) / a : x / c;

}
@@ -289,4 +248,68 @@ const ColorSpace ColorSpace::ACEScg() { 
    };

}



static const float2 ILLUMINANT_D50_XY = {0.34567f, 0.35850f};

static const float3 ILLUMINANT_D50_XYZ = {0.964212f, 1.0f, 0.825188f};

static const mat3 BRADFORD = mat3{

    float3{ 0.8951f, -0.7502f,  0.0389f},

    float3{ 0.2664f,  1.7135f, -0.0685f},

    float3{-0.1614f,  0.0367f,  1.0296f}

};



static mat3 adaptation(const mat3& matrix, const float3& srcWhitePoint, const float3& dstWhitePoint) {

    float3 srcLMS = matrix * srcWhitePoint;

    float3 dstLMS = matrix * dstWhitePoint;

    return inverse(matrix) * mat3{dstLMS / srcLMS} * matrix;

}



ColorSpace::Connector::Connector(

        const ColorSpace& src,

        const ColorSpace& dst) noexcept

        : mSource(src)

        , mDestination(dst) {



    if (all(lessThan(abs(src.getWhitePoint() - dst.getWhitePoint()), float2{1e-3f}))) {

        mTransform = dst.getXYZtoRGB() * src.getRGBtoXYZ();

    } else {

        mat3 rgbToXYZ(src.getRGBtoXYZ());

        mat3 xyzToRGB(dst.getXYZtoRGB());



        float3 srcXYZ = XYZ(float3{src.getWhitePoint(), 1});

        float3 dstXYZ = XYZ(float3{dst.getWhitePoint(), 1});



        if (any(greaterThan(abs(src.getWhitePoint() - ILLUMINANT_D50_XY), float2{1e-3f}))) {

            rgbToXYZ = adaptation(BRADFORD, srcXYZ, ILLUMINANT_D50_XYZ) * src.getRGBtoXYZ();

        }



        if (any(greaterThan(abs(dst.getWhitePoint() - ILLUMINANT_D50_XY), float2{1e-3f}))) {

            xyzToRGB = inverse(adaptation(BRADFORD, dstXYZ, ILLUMINANT_D50_XYZ) * dst.getRGBtoXYZ());

        }



        mTransform = xyzToRGB * rgbToXYZ;

    }

}



std::unique_ptr<float3> ColorSpace::createLUT(uint32_t size,

        const ColorSpace& src, const ColorSpace& dst) {



    size = clamp(size, 2u, 256u);

    float m = 1.0f / float(size - 1);



    std::unique_ptr<float3> lut(new float3[size * size * size]);

    float3* data = lut.get();



    Connector connector(src, dst);



    for (uint32_t z = 0; z < size; z++) {

        for (int32_t y = int32_t(size - 1); y >= 0; y--) {

            for (uint32_t x = 0; x < size; x++) {

                *data++ = connector.transform({x * m, y * m, z * m});

            }

        }

    }



    return lut;

}





}; // namespace android

libs/ui/tests/colorspace_test.cpp

+18 −0
Original line number Diff line number Diff line
@@ -162,4 +162,22 @@ TEST_F(ColorSpaceTest, Connect) { 
    EXPECT_TRUE(all(lessThan(abs(r - float3{0.70226f, 0.2757f, 0.1036f}), float3{1e-4f})));

}



TEST_F(ColorSpaceTest, LUT) {

    auto lut = ColorSpace::createLUT(17, ColorSpace::sRGB(), ColorSpace::AdobeRGB());

    EXPECT_TRUE(lut != nullptr);



    // {1.0f, 0.5f, 0.0f}

    auto r = lut.get()[0 * 17 * 17 + 8 * 17 + 16];

    EXPECT_TRUE(all(lessThan(abs(r - float3{0.8912f, 0.4962f, 0.1164f}), float3{1e-4f})));



    // {1.0f, 1.0f, 0.5f}

    r = lut.get()[8 * 17 * 17 + 0 * 17 + 16]; // y (G) is flipped

    EXPECT_TRUE(all(lessThan(abs(r - float3{1.0f, 1.0f, 0.5290f}), float3{1e-4f})));



    // {1.0f, 1.0f, 1.0f}

    r = lut.get()[16 * 17 * 17 + 0 * 17 + 16]; // y (G) is flipped

    EXPECT_TRUE(all(lessThan(abs(r - float3{1.0f, 1.0f, 1.0f}), float3{1e-4f})));



}



}; // namespace android