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Commit bbf0e156 authored by Michael Ludwig's avatar Michael Ludwig Committed by Android (Google) Code Review
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Merge "Update GainMap to assume it is rendering a linear surface" into main

parents e4623957 acf8b73c

libs/renderengine/skia/SkiaRenderEngine.cpp

+6 −0
Original line number Original line Diff line number Diff line
@@ -1370,6 +1370,12 @@ void SkiaRenderEngine::tonemapAndDrawGainmapInternal( 
    std::lock_guard<std::mutex> lock(mRenderingMutex);

    std::lock_guard<std::mutex> lock(mRenderingMutex);

    auto context = getActiveContext();

    auto context = getActiveContext();

    auto gainmapTextureRef = getOrCreateBackendTexture(gainmap->getBuffer(), true);

    auto gainmapTextureRef = getOrCreateBackendTexture(gainmap->getBuffer(), true);



    // The Dataspace used to create the SkSurface must be a linear colorspace in order to meet the

    // requirements for the gainmap shader. Since this is done via the dst colorspace and the shader

    // is painted into the surface directly, there is no need to wrap the gainmap shader with

    // `SkShader::makeWithWorkingColorSpace`. `hdrShader` and `sdrShader` will both output

    // values in the dst colorspace, which meets the linear gamma requirement.

    sk_sp<SkSurface> gainmapSurface =

    sk_sp<SkSurface> gainmapSurface =

            gainmapTextureRef->getOrCreateSurface(ui::Dataspace::V0_SRGB_LINEAR);

            gainmapTextureRef->getOrCreateSurface(ui::Dataspace::V0_SRGB_LINEAR);

libs/renderengine/skia/filters/GainmapFactory.cpp

+4 −2
Original line number Original line Diff line number Diff line
@@ -26,6 +26,8 @@ namespace skia { 
namespace {

namespace {





// Please refer to https://developer.android.com/media/platform/hdr-image-format#gain_map-generation

// Please refer to https://developer.android.com/media/platform/hdr-image-format#gain_map-generation

// This shader assumes that it will be used in a linear gamma colorspace context, e.g. all values

// sampled from `sdr` and `hdr` are linear and it is outputting an encoded ratio of luminances.

static const SkString kGainmapShaderString = SkString(R"(

static const SkString kGainmapShaderString = SkString(R"(

    uniform shader sdr;

    uniform shader sdr;

    uniform shader hdr;

    uniform shader hdr;
@@ -41,8 +43,8 @@ static const SkString kGainmapShaderString = SkString(R"( 
    }

    }





    vec4 main(vec2 xy) {

    vec4 main(vec2 xy) {

        float sdrY = luminance(toLinearSrgb(sdr.eval(xy).rgb));

        float sdrY = luminance(sdr.eval(xy).rgb);

        float hdrY = luminance(toLinearSrgb(hdr.eval(xy).rgb));

        float hdrY = luminance(hdr.eval(xy).rgb);

        float pixelGain = (hdrY + offsetHdr) / (sdrY + offsetSdr);

        float pixelGain = (hdrY + offsetHdr) / (sdrY + offsetSdr);

        float logRecovery = (log2(pixelGain) - mapMinLog2) / (mapMaxLog2 - mapMinLog2);

        float logRecovery = (log2(pixelGain) - mapMinLog2) / (mapMaxLog2 - mapMinLog2);

        return vec4(pow(clamp(logRecovery, 0.0, 1.0), mapGamma));

        return vec4(pow(clamp(logRecovery, 0.0, 1.0), mapGamma));