diff options
Diffstat (limited to 'libs/shaders/shaders.cpp')
| -rw-r--r-- | libs/shaders/shaders.cpp | 58 |
1 files changed, 39 insertions, 19 deletions
diff --git a/libs/shaders/shaders.cpp b/libs/shaders/shaders.cpp index a3c403e551..19518eaecc 100644 --- a/libs/shaders/shaders.cpp +++ b/libs/shaders/shaders.cpp @@ -191,31 +191,35 @@ void generateLuminanceScalesForOOTF(ui::Dataspace inputDataspace, ui::Dataspace )"); break; default: + // Input is SDR so map to its white point luminance switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) { - case HAL_DATASPACE_TRANSFER_ST2084: + // 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: - // SDR -> HDR tonemap shader.append(R"( float3 ScaleLuminance(float3 xyz) { - return xyz * in_libtonemap_inputMaxLuminance; + return xyz * 1000.0; } )"); break; default: - // Input and output are both SDR, so no tone-mapping is expected so - // no-op the luminance normalization. shader.append(R"( - float3 ScaleLuminance(float3 xyz) { - return xyz * in_libtonemap_displayMaxLuminance; - } - )"); + float3 ScaleLuminance(float3 xyz) { + return xyz * in_libtonemap_displayMaxLuminance; + } + )"); break; } } } // Normalizes from absolute light back to relative light (maps from [0, maxNits] back to [0, 1]) -static void generateLuminanceNormalizationForOOTF(ui::Dataspace outputDataspace, +static void generateLuminanceNormalizationForOOTF(ui::Dataspace inputDataspace, + ui::Dataspace outputDataspace, std::string& shader) { switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) { case HAL_DATASPACE_TRANSFER_ST2084: @@ -226,11 +230,28 @@ static void generateLuminanceNormalizationForOOTF(ui::Dataspace outputDataspace, )"); break; case HAL_DATASPACE_TRANSFER_HLG: - shader.append(R"( - float3 NormalizeLuminance(float3 xyz) { - return xyz / 1000.0; - } - )"); + switch (inputDataspace & HAL_DATASPACE_TRANSFER_MASK) { + case HAL_DATASPACE_TRANSFER_HLG: + shader.append(R"( + float3 NormalizeLuminance(float3 xyz) { + return xyz / 1000.0; + } + )"); + break; + default: + // Transcoding to HLG requires applying the inverse OOTF + // with the expectation that the OOTF is then applied during + // tonemapping downstream. + 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; + } + )"); + break; + } break; default: shader.append(R"( @@ -250,7 +271,7 @@ void generateOOTF(ui::Dataspace inputDataspace, ui::Dataspace outputDataspace, .c_str()); generateLuminanceScalesForOOTF(inputDataspace, outputDataspace, shader); - generateLuminanceNormalizationForOOTF(outputDataspace, shader); + generateLuminanceNormalizationForOOTF(inputDataspace, outputDataspace, shader); shader.append(R"( float3 OOTF(float3 linearRGB, float3 xyz) { @@ -501,9 +522,8 @@ std::vector<tonemap::ShaderUniform> buildLinearEffectUniforms( tonemap::Metadata metadata{.displayMaxLuminance = maxDisplayLuminance, // If the input luminance is unknown, use display luminance (aka, - // no-op any luminance changes) - // This will be the case for eg screenshots in addition to - // uncalibrated displays + // no-op any luminance changes). + // This is expected to only be meaningful for PQ content .contentMaxLuminance = maxLuminance > 0 ? maxLuminance : maxDisplayLuminance, .currentDisplayLuminance = currentDisplayLuminanceNits > 0 |