Align HLG and PQ color management to 203 nits == SDR max by default
The public HLG and PQ definitions map 203 nits to SDR white by scaling
the respective transfer functions.
Bug: 278121691
Bug: 278122024
Test: HwAccelerationTest test gradients
Test: HDR test videos match DPU and GPU composition
Test: SilkFX test HLG and PQ images
Change-Id: Id830e2ac72f5bcf8566556053fcf3af6b945581b
diff --git a/libs/shaders/shaders.cpp b/libs/shaders/shaders.cpp
index 19518ea..b8f2be1 100644
--- a/libs/shaders/shaders.cpp
+++ b/libs/shaders/shaders.cpp
@@ -33,187 +33,46 @@
return static_cast<aidl::android::hardware::graphics::common::Dataspace>(dataspace);
}
-void generateEOTF(ui::Dataspace dataspace, std::string& shader) {
- switch (dataspace & HAL_DATASPACE_TRANSFER_MASK) {
- case HAL_DATASPACE_TRANSFER_ST2084:
- shader.append(R"(
-
- float3 EOTF(float3 color) {
- float m1 = (2610.0 / 4096.0) / 4.0;
- float m2 = (2523.0 / 4096.0) * 128.0;
- float c1 = (3424.0 / 4096.0);
- float c2 = (2413.0 / 4096.0) * 32.0;
- float c3 = (2392.0 / 4096.0) * 32.0;
-
- float3 tmp = pow(clamp(color, 0.0, 1.0), 1.0 / float3(m2));
- tmp = max(tmp - c1, 0.0) / (c2 - c3 * tmp);
- return pow(tmp, 1.0 / float3(m1));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_HLG:
- shader.append(R"(
- float EOTF_channel(float channel) {
- const float a = 0.17883277;
- const float b = 0.28466892;
- const float c = 0.55991073;
- return channel <= 0.5 ? channel * channel / 3.0 :
- (exp((channel - c) / a) + b) / 12.0;
- }
-
- float3 EOTF(float3 color) {
- return float3(EOTF_channel(color.r), EOTF_channel(color.g),
- EOTF_channel(color.b));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_LINEAR:
- shader.append(R"(
- float3 EOTF(float3 color) {
- return color;
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_SMPTE_170M:
- shader.append(R"(
-
- float EOTF_sRGB(float srgb) {
- return srgb <= 0.08125 ? srgb / 4.50 : pow((srgb + 0.099) / 1.099, 1 / 0.45);
- }
-
- float3 EOTF_sRGB(float3 srgb) {
- return float3(EOTF_sRGB(srgb.r), EOTF_sRGB(srgb.g), EOTF_sRGB(srgb.b));
- }
-
- float3 EOTF(float3 srgb) {
- return sign(srgb.rgb) * EOTF_sRGB(abs(srgb.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_GAMMA2_2:
- shader.append(R"(
-
- float EOTF_sRGB(float srgb) {
- return pow(srgb, 2.2);
- }
-
- float3 EOTF_sRGB(float3 srgb) {
- return float3(EOTF_sRGB(srgb.r), EOTF_sRGB(srgb.g), EOTF_sRGB(srgb.b));
- }
-
- float3 EOTF(float3 srgb) {
- return sign(srgb.rgb) * EOTF_sRGB(abs(srgb.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_GAMMA2_6:
- shader.append(R"(
-
- float EOTF_sRGB(float srgb) {
- return pow(srgb, 2.6);
- }
-
- float3 EOTF_sRGB(float3 srgb) {
- return float3(EOTF_sRGB(srgb.r), EOTF_sRGB(srgb.g), EOTF_sRGB(srgb.b));
- }
-
- float3 EOTF(float3 srgb) {
- return sign(srgb.rgb) * EOTF_sRGB(abs(srgb.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_GAMMA2_8:
- shader.append(R"(
-
- float EOTF_sRGB(float srgb) {
- return pow(srgb, 2.8);
- }
-
- float3 EOTF_sRGB(float3 srgb) {
- return float3(EOTF_sRGB(srgb.r), EOTF_sRGB(srgb.g), EOTF_sRGB(srgb.b));
- }
-
- float3 EOTF(float3 srgb) {
- return sign(srgb.rgb) * EOTF_sRGB(abs(srgb.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_SRGB:
- default:
- shader.append(R"(
-
- float EOTF_sRGB(float srgb) {
- return srgb <= 0.04045 ? srgb / 12.92 : pow((srgb + 0.055) / 1.055, 2.4);
- }
-
- float3 EOTF_sRGB(float3 srgb) {
- return float3(EOTF_sRGB(srgb.r), EOTF_sRGB(srgb.g), EOTF_sRGB(srgb.b));
- }
-
- float3 EOTF(float3 srgb) {
- return sign(srgb.rgb) * EOTF_sRGB(abs(srgb.rgb));
- }
- )");
- break;
- }
-}
-
void generateXYZTransforms(std::string& shader) {
shader.append(R"(
- uniform float4x4 in_rgbToXyz;
- uniform float4x4 in_xyzToRgb;
+ uniform float3x3 in_rgbToXyz;
+ uniform float3x3 in_xyzToSrcRgb;
+ uniform float4x4 in_colorTransform;
float3 ToXYZ(float3 rgb) {
- return (in_rgbToXyz * float4(rgb, 1.0)).rgb;
+ return in_rgbToXyz * rgb;
}
- float3 ToRGB(float3 xyz) {
- return clamp((in_xyzToRgb * float4(xyz, 1.0)).rgb, 0.0, 1.0);
+ float3 ToSrcRGB(float3 xyz) {
+ return in_xyzToSrcRgb * xyz;
+ }
+
+ float3 ApplyColorTransform(float3 rgb) {
+ return (in_colorTransform * float4(rgb, 1.0)).rgb;
}
)");
}
-// Conversion from relative light to absolute light (maps from [0, 1] to [0, maxNits])
-void generateLuminanceScalesForOOTF(ui::Dataspace inputDataspace, ui::Dataspace outputDataspace,
- std::string& shader) {
+// Conversion from relative light to absolute light
+// Note that 1.0 == 203 nits.
+void generateLuminanceScalesForOOTF(ui::Dataspace inputDataspace, std::string& shader) {
switch (inputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
- case HAL_DATASPACE_TRANSFER_ST2084:
- shader.append(R"(
- float3 ScaleLuminance(float3 xyz) {
- return xyz * 10000.0;
- }
- )");
- break;
case HAL_DATASPACE_TRANSFER_HLG:
+ // BT. 2408 says that a signal level of 0.75 == 203 nits for HLG, but that's after
+ // applying OOTF. But we haven't applied OOTF yet, so we need to scale by a different
+ // constant instead.
shader.append(R"(
- float3 ScaleLuminance(float3 xyz) {
- return xyz * 1000.0;
- }
- )");
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * 264.96;
+ }
+ )");
break;
default:
- // Input is SDR so map to its white point luminance
- switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
- // Max HLG output is nominally 1000 nits, but BT. 2100-2 allows
- // for gamma correcting the HLG OOTF for displays with a different
- // dynamic range. Scale to 1000 nits to apply an inverse OOTF against
- // a reference display correctly.
- // TODO: Use knowledge of the dimming ratio here to prevent
- // unintended gamma shaft.
- case HAL_DATASPACE_TRANSFER_HLG:
- shader.append(R"(
- float3 ScaleLuminance(float3 xyz) {
- return xyz * 1000.0;
- }
- )");
- break;
- default:
- shader.append(R"(
- float3 ScaleLuminance(float3 xyz) {
- return xyz * in_libtonemap_displayMaxLuminance;
- }
- )");
- break;
- }
+ shader.append(R"(
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * 203.0;
+ }
+ )");
+ break;
}
}
@@ -224,17 +83,17 @@
switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
case HAL_DATASPACE_TRANSFER_ST2084:
shader.append(R"(
- float3 NormalizeLuminance(float3 xyz) {
- return xyz / 10000.0;
- }
- )");
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / 203.0;
+ }
+ )");
break;
case HAL_DATASPACE_TRANSFER_HLG:
switch (inputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
case HAL_DATASPACE_TRANSFER_HLG:
shader.append(R"(
float3 NormalizeLuminance(float3 xyz) {
- return xyz / 1000.0;
+ return xyz / 264.96;
}
)");
break;
@@ -242,24 +101,39 @@
// Transcoding to HLG requires applying the inverse OOTF
// with the expectation that the OOTF is then applied during
// tonemapping downstream.
+ // BT. 2100-2 operates on normalized luminances, so renormalize to the input to
+ // correctly adjust gamma.
shader.append(R"(
float3 NormalizeLuminance(float3 xyz) {
- // BT. 2100-2 operates on normalized luminances,
- // so renormalize to the input
- float ootfGain = pow(xyz.y / 1000.0, -0.2 / 1.2) / 1000.0;
- return xyz * ootfGain;
+ float ootfGain = pow(xyz.y / 1000.0, -0.2 / 1.2);
+ return xyz * ootfGain / 203.0;
}
)");
break;
}
break;
default:
- shader.append(R"(
- float3 NormalizeLuminance(float3 xyz) {
- return xyz / in_libtonemap_displayMaxLuminance;
- }
- )");
- break;
+ switch (inputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_HLG:
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ // libtonemap outputs a range [0, in_libtonemap_displayMaxLuminance], so
+ // normalize back to [0, 1] when the output is SDR.
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / in_libtonemap_displayMaxLuminance;
+ }
+ )");
+ break;
+ default:
+ // Otherwise normalize back down to the range [0, 1]
+ // TODO: get this working for extended range outputs
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / 203.0;
+ }
+ )");
+ break;
+ }
}
}
@@ -270,145 +144,34 @@
toAidlDataspace(outputDataspace))
.c_str());
- generateLuminanceScalesForOOTF(inputDataspace, outputDataspace, shader);
+ generateLuminanceScalesForOOTF(inputDataspace, shader);
generateLuminanceNormalizationForOOTF(inputDataspace, outputDataspace, shader);
+ // Some tonemappers operate on CIE luminance, other tonemappers operate on linear rgb
+ // luminance in the source gamut.
shader.append(R"(
- float3 OOTF(float3 linearRGB, float3 xyz) {
+ float3 OOTF(float3 linearRGB) {
float3 scaledLinearRGB = ScaleLuminance(linearRGB);
- float3 scaledXYZ = ScaleLuminance(xyz);
+ float3 scaledXYZ = ToXYZ(scaledLinearRGB);
- float gain = libtonemap_LookupTonemapGain(scaledLinearRGB, scaledXYZ);
+ float gain = libtonemap_LookupTonemapGain(ToSrcRGB(scaledXYZ), scaledXYZ);
return NormalizeLuminance(scaledXYZ * gain);
}
)");
}
-void generateOETF(ui::Dataspace dataspace, std::string& shader) {
- switch (dataspace & HAL_DATASPACE_TRANSFER_MASK) {
- case HAL_DATASPACE_TRANSFER_ST2084:
- shader.append(R"(
-
- float3 OETF(float3 xyz) {
- float m1 = (2610.0 / 4096.0) / 4.0;
- float m2 = (2523.0 / 4096.0) * 128.0;
- float c1 = (3424.0 / 4096.0);
- float c2 = (2413.0 / 4096.0) * 32.0;
- float c3 = (2392.0 / 4096.0) * 32.0;
-
- float3 tmp = pow(xyz, float3(m1));
- tmp = (c1 + c2 * tmp) / (1.0 + c3 * tmp);
- return pow(tmp, float3(m2));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_HLG:
- shader.append(R"(
- float OETF_channel(float channel) {
- const float a = 0.17883277;
- const float b = 0.28466892;
- const float c = 0.55991073;
- return channel <= 1.0 / 12.0 ? sqrt(3.0 * channel) :
- a * log(12.0 * channel - b) + c;
- }
-
- float3 OETF(float3 linear) {
- return float3(OETF_channel(linear.r), OETF_channel(linear.g),
- OETF_channel(linear.b));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_LINEAR:
- shader.append(R"(
- float3 OETF(float3 linear) {
- return linear;
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_SMPTE_170M:
- shader.append(R"(
- float OETF_sRGB(float linear) {
- return linear <= 0.018 ?
- linear * 4.50 : (pow(linear, 0.45) * 1.099) - 0.099;
- }
-
- float3 OETF_sRGB(float3 linear) {
- return float3(OETF_sRGB(linear.r), OETF_sRGB(linear.g), OETF_sRGB(linear.b));
- }
-
- float3 OETF(float3 linear) {
- return sign(linear.rgb) * OETF_sRGB(abs(linear.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_GAMMA2_2:
- shader.append(R"(
- float OETF_sRGB(float linear) {
- return pow(linear, (1.0 / 2.2));
- }
-
- float3 OETF_sRGB(float3 linear) {
- return float3(OETF_sRGB(linear.r), OETF_sRGB(linear.g), OETF_sRGB(linear.b));
- }
-
- float3 OETF(float3 linear) {
- return sign(linear.rgb) * OETF_sRGB(abs(linear.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_GAMMA2_6:
- shader.append(R"(
- float OETF_sRGB(float linear) {
- return pow(linear, (1.0 / 2.6));
- }
-
- float3 OETF_sRGB(float3 linear) {
- return float3(OETF_sRGB(linear.r), OETF_sRGB(linear.g), OETF_sRGB(linear.b));
- }
-
- float3 OETF(float3 linear) {
- return sign(linear.rgb) * OETF_sRGB(abs(linear.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_GAMMA2_8:
- shader.append(R"(
- float OETF_sRGB(float linear) {
- return pow(linear, (1.0 / 2.8));
- }
-
- float3 OETF_sRGB(float3 linear) {
- return float3(OETF_sRGB(linear.r), OETF_sRGB(linear.g), OETF_sRGB(linear.b));
- }
-
- float3 OETF(float3 linear) {
- return sign(linear.rgb) * OETF_sRGB(abs(linear.rgb));
- }
- )");
- break;
- case HAL_DATASPACE_TRANSFER_SRGB:
- default:
- shader.append(R"(
- float OETF_sRGB(float linear) {
- return linear <= 0.0031308 ?
- linear * 12.92 : (pow(linear, 1.0 / 2.4) * 1.055) - 0.055;
- }
-
- float3 OETF_sRGB(float3 linear) {
- return float3(OETF_sRGB(linear.r), OETF_sRGB(linear.g), OETF_sRGB(linear.b));
- }
-
- float3 OETF(float3 linear) {
- return sign(linear.rgb) * OETF_sRGB(abs(linear.rgb));
- }
- )");
- break;
- }
+void generateOETF(std::string& shader) {
+ // Only support gamma 2.2 for now
+ shader.append(R"(
+ float OETF(float3 linear) {
+ return sign(linear) * pow(abs(linear), (1.0 / 2.2));
+ }
+ )");
}
void generateEffectiveOOTF(bool undoPremultipliedAlpha, LinearEffect::SkSLType type,
- std::string& shader) {
+ bool needsCustomOETF, std::string& shader) {
switch (type) {
case LinearEffect::SkSLType::ColorFilter:
shader.append(R"(
@@ -429,11 +192,19 @@
c.rgb = c.rgb / (c.a + 0.0019);
)");
}
+ // We are using linear sRGB as a working space, with 1.0 == 203 nits
shader.append(R"(
- float3 linearRGB = EOTF(c.rgb);
- float3 xyz = ToXYZ(linearRGB);
- c.rgb = OETF(ToRGB(OOTF(linearRGB, xyz)));
+ c.rgb = ApplyColorTransform(OOTF(toLinearSrgb(c.rgb)));
)");
+ if (needsCustomOETF) {
+ shader.append(R"(
+ c.rgb = OETF(c.rgb);
+ )");
+ } else {
+ shader.append(R"(
+ c.rgb = fromLinearSrgb(c.rgb);
+ )");
+ }
if (undoPremultipliedAlpha) {
shader.append(R"(
c.rgb = c.rgb * (c.a + 0.0019);
@@ -445,33 +216,6 @@
)");
}
-// please keep in sync with toSkColorSpace function in renderengine/skia/ColorSpaces.cpp
-ColorSpace toColorSpace(ui::Dataspace dataspace) {
- switch (dataspace & HAL_DATASPACE_STANDARD_MASK) {
- case HAL_DATASPACE_STANDARD_BT709:
- return ColorSpace::sRGB();
- case HAL_DATASPACE_STANDARD_DCI_P3:
- return ColorSpace::DisplayP3();
- case HAL_DATASPACE_STANDARD_BT2020:
- case HAL_DATASPACE_STANDARD_BT2020_CONSTANT_LUMINANCE:
- return ColorSpace::BT2020();
- case HAL_DATASPACE_STANDARD_ADOBE_RGB:
- return ColorSpace::AdobeRGB();
- // TODO(b/208290320): BT601 format and variants return different primaries
- case HAL_DATASPACE_STANDARD_BT601_625:
- case HAL_DATASPACE_STANDARD_BT601_625_UNADJUSTED:
- case HAL_DATASPACE_STANDARD_BT601_525:
- case HAL_DATASPACE_STANDARD_BT601_525_UNADJUSTED:
- // TODO(b/208290329): BT407M format returns different primaries
- case HAL_DATASPACE_STANDARD_BT470M:
- // TODO(b/208290904): FILM format returns different primaries
- case HAL_DATASPACE_STANDARD_FILM:
- case HAL_DATASPACE_STANDARD_UNSPECIFIED:
- default:
- return ColorSpace::sRGB();
- }
-}
-
template <typename T, std::enable_if_t<std::is_trivially_copyable<T>::value, bool> = true>
std::vector<uint8_t> buildUniformValue(T value) {
std::vector<uint8_t> result;
@@ -484,17 +228,45 @@
std::string buildLinearEffectSkSL(const LinearEffect& linearEffect) {
std::string shaderString;
- generateEOTF(linearEffect.fakeInputDataspace == ui::Dataspace::UNKNOWN
- ? linearEffect.inputDataspace
- : linearEffect.fakeInputDataspace,
- shaderString);
generateXYZTransforms(shaderString);
generateOOTF(linearEffect.inputDataspace, linearEffect.outputDataspace, shaderString);
- generateOETF(linearEffect.outputDataspace, shaderString);
- generateEffectiveOOTF(linearEffect.undoPremultipliedAlpha, linearEffect.type, shaderString);
+
+ const bool needsCustomOETF = (linearEffect.fakeOutputDataspace & HAL_DATASPACE_TRANSFER_MASK) ==
+ HAL_DATASPACE_TRANSFER_GAMMA2_2;
+ if (needsCustomOETF) {
+ generateOETF(shaderString);
+ }
+ generateEffectiveOOTF(linearEffect.undoPremultipliedAlpha, linearEffect.type, needsCustomOETF,
+ shaderString);
return shaderString;
}
+ColorSpace toColorSpace(ui::Dataspace dataspace) {
+ switch (dataspace & HAL_DATASPACE_STANDARD_MASK) {
+ case HAL_DATASPACE_STANDARD_BT709:
+ return ColorSpace::sRGB();
+ case HAL_DATASPACE_STANDARD_DCI_P3:
+ return ColorSpace::DisplayP3();
+ case HAL_DATASPACE_STANDARD_BT2020:
+ case HAL_DATASPACE_STANDARD_BT2020_CONSTANT_LUMINANCE:
+ return ColorSpace::BT2020();
+ case HAL_DATASPACE_STANDARD_ADOBE_RGB:
+ return ColorSpace::AdobeRGB();
+ // TODO(b/208290320): BT601 format and variants return different primaries
+ case HAL_DATASPACE_STANDARD_BT601_625:
+ case HAL_DATASPACE_STANDARD_BT601_625_UNADJUSTED:
+ case HAL_DATASPACE_STANDARD_BT601_525:
+ case HAL_DATASPACE_STANDARD_BT601_525_UNADJUSTED:
+ // TODO(b/208290329): BT407M format returns different primaries
+ case HAL_DATASPACE_STANDARD_BT470M:
+ // TODO(b/208290904): FILM format returns different primaries
+ case HAL_DATASPACE_STANDARD_FILM:
+ case HAL_DATASPACE_STANDARD_UNSPECIFIED:
+ default:
+ return ColorSpace::sRGB();
+ }
+}
+
// Generates a list of uniforms to set on the LinearEffect shader above.
std::vector<tonemap::ShaderUniform> buildLinearEffectUniforms(
const LinearEffect& linearEffect, const mat4& colorTransform, float maxDisplayLuminance,
@@ -502,23 +274,24 @@
aidl::android::hardware::graphics::composer3::RenderIntent renderIntent) {
std::vector<tonemap::ShaderUniform> uniforms;
- const ui::Dataspace inputDataspace = linearEffect.fakeInputDataspace == ui::Dataspace::UNKNOWN
- ? linearEffect.inputDataspace
- : linearEffect.fakeInputDataspace;
+ auto inputColorSpace = toColorSpace(linearEffect.inputDataspace);
+ auto outputColorSpace = toColorSpace(linearEffect.outputDataspace);
- if (inputDataspace == linearEffect.outputDataspace) {
- uniforms.push_back({.name = "in_rgbToXyz", .value = buildUniformValue<mat4>(mat4())});
- uniforms.push_back(
- {.name = "in_xyzToRgb", .value = buildUniformValue<mat4>(colorTransform)});
- } else {
- ColorSpace inputColorSpace = toColorSpace(inputDataspace);
- ColorSpace outputColorSpace = toColorSpace(linearEffect.outputDataspace);
- uniforms.push_back({.name = "in_rgbToXyz",
- .value = buildUniformValue<mat4>(mat4(inputColorSpace.getRGBtoXYZ()))});
- uniforms.push_back({.name = "in_xyzToRgb",
- .value = buildUniformValue<mat4>(
- colorTransform * mat4(outputColorSpace.getXYZtoRGB()))});
- }
+ uniforms.push_back(
+ {.name = "in_rgbToXyz",
+ .value = buildUniformValue<mat3>(ColorSpace::linearExtendedSRGB().getRGBtoXYZ())});
+ uniforms.push_back({.name = "in_xyzToSrcRgb",
+ .value = buildUniformValue<mat3>(inputColorSpace.getXYZtoRGB())});
+ // Transforms xyz colors to linear source colors, then applies the color transform, then
+ // transforms to linear extended RGB for skia to color manage.
+ uniforms.push_back({.name = "in_colorTransform",
+ .value = buildUniformValue<mat4>(
+ mat4(ColorSpace::linearExtendedSRGB().getXYZtoRGB()) *
+ // TODO: the color transform ideally should be applied
+ // in the source colorspace, but doing that breaks
+ // renderengine tests
+ mat4(outputColorSpace.getRGBtoXYZ()) * colorTransform *
+ mat4(outputColorSpace.getXYZtoRGB()))});
tonemap::Metadata metadata{.displayMaxLuminance = maxDisplayLuminance,
// If the input luminance is unknown, use display luminance (aka,