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Commit b658b15c authored by Sally Qi's avatar Sally Qi
Browse files

[Lut shader] Fix gamma correction 

to avoid color conversion, we de-gamma the image without changing the
primaries, after lut(s) shader being applied, we need to re-gamma it
back.

Bug: 329472856
Test: luts cts cases
Flag: android.hardware.flags.luts_api
Change-Id: I8c8a3b6d445d11efab4115c097d7eeb91d1be384
parent 44d6fff4

libs/renderengine/skia/SkiaRenderEngine.cpp

+2 −1
Original line number Diff line number Diff line
@@ -544,7 +544,8 @@ sk_sp<SkShader> SkiaRenderEngine::createRuntimeEffectShader( 
    }



    if (graphicBuffer && parameters.layer.luts) {

        shader = mLutShader.lutShader(shader, parameters.layer.luts);

        shader = mLutShader.lutShader(shader, parameters.layer.luts,

                                      toSkColorSpace(parameters.outputDataSpace));

    }



    if (parameters.requiresLinearEffect) {

libs/renderengine/skia/filters/LutShader.cpp

+10 −19
Original line number Diff line number Diff line
@@ -169,7 +169,8 @@ sk_sp<SkShader> LutShader::generateLutShader(sk_sp<SkShader> input, 
}



sk_sp<SkShader> LutShader::lutShader(sk_sp<SkShader>& input,

                                     std::shared_ptr<gui::DisplayLuts> displayLuts) {

                                     std::shared_ptr<gui::DisplayLuts> displayLuts,

                                     sk_sp<SkColorSpace> outColorSpace) {

    if (mBuilder == nullptr) {

        const static SkRuntimeEffect::Result instance = SkRuntimeEffect::MakeForShader(kShader);

        mBuilder = std::make_unique<SkRuntimeShaderBuilder>(instance.effect);
@@ -179,14 +180,11 @@ sk_sp<SkShader> LutShader::lutShader(sk_sp<SkShader>& input, 
    if (fd.ok()) {

        // de-gamma the image without changing the primaries

        SkImage* baseImage = input->isAImage((SkMatrix*)nullptr, (SkTileMode*)nullptr);

        if (baseImage) {

            sk_sp<SkColorSpace> baseColorSpace =

                    baseImage->colorSpace() ? baseImage->refColorSpace() : SkColorSpace::MakeSRGB();

            sk_sp<SkColorSpace> gainmapMathColorSpace = baseColorSpace->makeLinearGamma();

            auto colorXformSdrToGainmap =

                    SkColorFilterPriv::MakeColorSpaceXform(baseColorSpace, gainmapMathColorSpace);

            input = input->makeWithColorFilter(colorXformSdrToGainmap);

        }

        sk_sp<SkColorSpace> baseColorSpace = baseImage && baseImage->colorSpace()

                ? baseImage->refColorSpace()

                : SkColorSpace::MakeSRGB();

        sk_sp<SkColorSpace> lutMathColorSpace = baseColorSpace->makeLinearGamma();

        input = input->makeWithWorkingColorSpace(lutMathColorSpace);



        auto& offsets = displayLuts->offsets;

        auto& lutProperties = displayLuts->lutProperties;
@@ -223,16 +221,9 @@ sk_sp<SkShader> LutShader::lutShader(sk_sp<SkShader>& input, 
                                      lutProperties[i].samplingKey);

        }



        // re-gamma

        baseImage = input->isAImage((SkMatrix*)nullptr, (SkTileMode*)nullptr);

        if (baseImage) {

            sk_sp<SkColorSpace> baseColorSpace =

                    baseImage->colorSpace() ? baseImage->refColorSpace() : SkColorSpace::MakeSRGB();

            sk_sp<SkColorSpace> gainmapMathColorSpace = baseColorSpace->makeLinearGamma();

            auto colorXformGainmapToDst =

                    SkColorFilterPriv::MakeColorSpaceXform(gainmapMathColorSpace, baseColorSpace);

            input = input->makeWithColorFilter(colorXformGainmapToDst);

        }

        auto colorXformLutToDst =

                SkColorFilterPriv::MakeColorSpaceXform(lutMathColorSpace, outColorSpace);

        input = input->makeWithColorFilter(colorXformLutToDst);

    }

    return input;

}

libs/renderengine/skia/filters/LutShader.h

+2 −2
Original line number Diff line number Diff line
@@ -28,8 +28,8 @@ namespace skia { 


class LutShader {

public:

    sk_sp<SkShader> lutShader(sk_sp<SkShader>& input,

                              std::shared_ptr<gui::DisplayLuts> displayLuts);

    sk_sp<SkShader> lutShader(sk_sp<SkShader>& input, std::shared_ptr<gui::DisplayLuts> displayLuts,

                              sk_sp<SkColorSpace> outColorSpace);



private:

    sk_sp<SkShader> generateLutShader(sk_sp<SkShader> input, const std::vector<float>& buffers,