Merge "[Lut shader] Fix the issue if using HLG/PQ transfer function." into main

1 files changed, 23 insertions, 8 deletions

diff --git a/libs/renderengine/skia/filters/LutShader.cpp b/libs/renderengine/skia/filters/LutShader.cpp
index 5e9dfbba3e..8fc3286c07 100644
--- a/libs/renderengine/skia/filters/LutShader.cpp
+++ b/libs/renderengine/skia/filters/LutShader.cpp
@@ -39,10 +39,13 @@ static const SkString kShader = SkString(R"(
     uniform int key;
     uniform int dimension;
     uniform vec3 luminanceCoefficients; // for CIE_Y
+    // for hlg/pq transfer function, we need normalize it to [0.0, 1.0]
+    // we use `normalizeScalar` to do so
+    uniform float normalizeScalar;
 
     vec4 main(vec2 xy) {
         float4 rgba = image.eval(xy);
-        float3 linear = toLinearSrgb(rgba.rgb);
+        float3 linear = toLinearSrgb(rgba.rgb) * normalizeScalar;
         if (dimension == 1) {
             // RGB
             if (key == 0) {
@@ -52,19 +55,19 @@ static const SkString kShader = SkString(R"(
                 float gainR = lut.eval(vec2(indexR, 0.0) + 0.5).r;
                 float gainG = lut.eval(vec2(indexG, 0.0) + 0.5).r;
                 float gainB = lut.eval(vec2(indexB, 0.0) + 0.5).r;
-                return float4(linear.r * gainR, linear.g * gainG, linear.b * gainB, rgba.a);
+                linear = float3(linear.r * gainR, linear.g * gainG, linear.b * gainB);
             // MAX_RGB
             } else if (key == 1) {
                 float maxRGB = max(linear.r, max(linear.g, linear.b));
                 float index = maxRGB * float(size - 1);
                 float gain = lut.eval(vec2(index, 0.0) + 0.5).r;
-                return float4(linear * gain, rgba.a);
+                linear = linear * gain;
             // CIE_Y
             } else if (key == 2) {
                 float y = dot(linear, luminanceCoefficients) / 3.0;
                 float index = y * float(size - 1);
                 float gain = lut.eval(vec2(index, 0.0) + 0.5).r;
-                return float4(linear * gain, rgba.a);
+                linear = linear * gain;
             }
         } else if (dimension == 3) {
             if (key == 0) {
@@ -110,12 +113,10 @@ static const SkString kShader = SkString(R"(
                 float3 c0 = mix(c00, c10, linear.g);
                 float3 c1 = mix(c01, c11, linear.g);
 
-                float3 val = mix(c0, c1, linear.b);
-
-                return float4(val, rgba.a);
+                linear = mix(c0, c1, linear.b);
             }
         }
-        return rgba;
+        return float4(linear, rgba.a);
     })");
 
 // same as shader::toColorSpace function
@@ -197,9 +198,22 @@ sk_sp<SkShader> LutShader::generateLutShader(sk_sp<SkShader> input,
                                             ? SkSamplingOptions(SkFilterMode::kLinear)
                                             : SkSamplingOptions());
 
+    float normalizeScalar = 1.0;
+    switch (srcDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+        case HAL_DATASPACE_TRANSFER_HLG:
+            normalizeScalar = 0.203;
+            break;
+        case HAL_DATASPACE_TRANSFER_ST2084:
+            normalizeScalar = 0.0203;
+            break;
+        default:
+            normalizeScalar = 1.0;
+    }
     const int uSize = static_cast<int>(size);
     const int uKey = static_cast<int>(samplingKey);
     const int uDimension = static_cast<int>(dimension);
+    const float uNormalizeScalar = static_cast<float>(normalizeScalar);
+
     if (static_cast<LutProperties::SamplingKey>(samplingKey) == LutProperties::SamplingKey::CIE_Y) {
         // Use predefined colorspaces of input dataspace so that we can get D65 illuminant
         mat3 toXYZMatrix(toColorSpace(srcDataspace).getRGBtoXYZ());
@@ -211,6 +225,7 @@ sk_sp<SkShader> LutShader::generateLutShader(sk_sp<SkShader> input,
     mBuilder->uniform("size") = uSize;
     mBuilder->uniform("key") = uKey;
     mBuilder->uniform("dimension") = uDimension;
+    mBuilder->uniform("normalizeScalar") = uNormalizeScalar;
     return mBuilder->makeShader();
 }