surfaceflinger: add BT2020_PQ support to RenderEngine
Add Key::Y410_BT2020_ON which performs Y410/BT2020 YUV -> RGB
conversion.
Add Key::{INPUT,OUTPUT}_TF_ST2084 which performs ST2084 EOTF and
OETF conversions.
Add Key::TONE_MAP_ON which performs tone-mapping.
Flip proper bits on when the source buffer has BT2020_PQ as its
dataspace. That means,
1. convert YUV to RGB
2. apply ST 2084 EOTF
3. apply tone-mapping
4. convert to DisplayP3
5. apply relative rendering intent (i.e., clamp)
6. finally apply sRGB OETF
We still use hardcoded parameters rather than the ones from HDR
metadata. It is also likely that we will need to switch to a LUT
for better perf.
Test: manual
Change-Id: I53556a2acfc34ef55e88c5b139000be94072dd3e
diff --git a/services/surfaceflinger/RenderEngine/ProgramCache.cpp b/services/surfaceflinger/RenderEngine/ProgramCache.cpp
index 30d2369..7a43ea9 100644
--- a/services/surfaceflinger/RenderEngine/ProgramCache.cpp
+++ b/services/surfaceflinger/RenderEngine/ProgramCache.cpp
@@ -128,6 +128,9 @@
.set(Key::COLOR_MATRIX_MASK,
description.mColorMatrixEnabled ? Key::COLOR_MATRIX_ON : Key::COLOR_MATRIX_OFF);
+ needs.set(Key::Y410_BT2020_MASK,
+ description.mY410BT2020 ? Key::Y410_BT2020_ON : Key::Y410_BT2020_OFF);
+
if (needs.hasColorMatrix()) {
switch (description.mInputTransferFunction) {
case Description::TransferFunction::LINEAR:
@@ -137,6 +140,9 @@
case Description::TransferFunction::SRGB:
needs.set(Key::INPUT_TF_MASK, Key::INPUT_TF_SRGB);
break;
+ case Description::TransferFunction::ST2084:
+ needs.set(Key::INPUT_TF_MASK, Key::INPUT_TF_ST2084);
+ break;
}
switch (description.mOutputTransferFunction) {
@@ -147,7 +153,13 @@
case Description::TransferFunction::SRGB:
needs.set(Key::OUTPUT_TF_MASK, Key::OUTPUT_TF_SRGB);
break;
+ case Description::TransferFunction::ST2084:
+ needs.set(Key::OUTPUT_TF_MASK, Key::OUTPUT_TF_ST2084);
+ break;
}
+
+ needs.set(Key::TONE_MAPPING_MASK,
+ description.mToneMappingEnabled ? Key::TONE_MAPPING_ON : Key::TONE_MAPPING_OFF);
}
return needs;
@@ -191,6 +203,20 @@
fs << "uniform vec4 color;";
}
+ if (needs.isY410BT2020()) {
+ fs << R"__SHADER__(
+ vec3 convertY410BT2020(const vec3 color) {
+ const vec3 offset = vec3(0.0625, 0.5, 0.5);
+ const mat3 transform = mat3(
+ vec3(1.1678, 1.1678, 1.1678),
+ vec3( 0.0, -0.1878, 2.1481),
+ vec3(1.6836, -0.6523, 0.0));
+ // Y is in G, U is in R, and V is in B
+ return clamp(transform * (color.grb - offset), 0.0, 1.0);
+ }
+ )__SHADER__";
+ }
+
if (needs.hasColorMatrix()) {
fs << "uniform mat4 colorMatrix;";
@@ -218,6 +244,21 @@
}
)__SHADER__";
break;
+ case Key::INPUT_TF_ST2084:
+ fs << R"__SHADER__(
+ vec3 EOTF(const highp vec3 color) {
+ const highp float m1 = (2610.0 / 4096.0) / 4.0;
+ const highp float m2 = (2523.0 / 4096.0) * 128.0;
+ const highp float c1 = (3424.0 / 4096.0);
+ const highp float c2 = (2413.0 / 4096.0) * 32.0;
+ const highp float c3 = (2392.0 / 4096.0) * 32.0;
+
+ highp vec3 tmp = pow(color, 1.0 / vec3(m2));
+ tmp = max(tmp - c1, 0.0) / (c2 - c3 * tmp);
+ return pow(tmp, 1.0 / vec3(m1));
+ }
+ )__SHADER__";
+ break;
}
switch (needs.getOutputTF()) {
@@ -245,12 +286,103 @@
}
)__SHADER__";
break;
+ case Key::OUTPUT_TF_ST2084:
+ fs << R"__SHADER__(
+ vec3 OETF(const vec3 linear) {
+ const float m1 = (2610.0 / 4096.0) / 4.0;
+ const float m2 = (2523.0 / 4096.0) * 128.0;
+ const float c1 = (3424.0 / 4096.0);
+ const float c2 = (2413.0 / 4096.0) * 32.0;
+ const float c3 = (2392.0 / 4096.0) * 32.0;
+
+ vec3 tmp = pow(linear, vec3(m1));
+ tmp = (c1 + c2 * tmp) / (1.0 + c3 * tmp);
+ return pow(tmp, vec3(m2));
+ }
+ )__SHADER__";
+ break;
+ }
+
+ if (needs.hasToneMapping()) {
+ fs << R"__SHADER__(
+ float ToneMapChannel(const float color) {
+ const float maxLumi = 10000.0;
+ const float maxMasteringLumi = 1000.0;
+ const float maxContentLumi = 1000.0;
+ const float maxInLumi = min(maxMasteringLumi, maxContentLumi);
+ const float maxOutLumi = 500.0;
+
+ // convert to nits first
+ float nits = color * maxLumi;
+
+ // clamp to max input luminance
+ nits = clamp(nits, 0.0, maxInLumi);
+
+ // scale [0.0, maxInLumi] to [0.0, maxOutLumi]
+ if (maxInLumi <= maxOutLumi) {
+ nits *= maxOutLumi / maxInLumi;
+ } else {
+ // three control points
+ const float x0 = 10.0;
+ const float y0 = 17.0;
+ const float x1 = maxOutLumi * 0.75;
+ const float y1 = x1;
+ const float x2 = x1 + (maxInLumi - x1) / 2.0;
+ const float y2 = y1 + (maxOutLumi - y1) * 0.75;
+
+ // horizontal distances between the last three control points
+ const float h12 = x2 - x1;
+ const float h23 = maxInLumi - x2;
+ // tangents at the last three control points
+ const float m1 = (y2 - y1) / h12;
+ const float m3 = (maxOutLumi - y2) / h23;
+ const float m2 = (m1 + m3) / 2.0;
+
+ if (nits < x0) {
+ // scale [0.0, x0] to [0.0, y0] linearly
+ const float slope = y0 / x0;
+ nits *= slope;
+ } else if (nits < x1) {
+ // scale [x0, x1] to [y0, y1] linearly
+ const float slope = (y1 - y0) / (x1 - x0);
+ nits = y0 + (nits - x0) * slope;
+ } else if (nits < x2) {
+ // scale [x1, x2] to [y1, y2] using Hermite interp
+ float t = (nits - x1) / h12;
+ nits = (y1 * (1.0 + 2.0 * t) + h12 * m1 * t) * (1.0 - t) * (1.0 - t) +
+ (y2 * (3.0 - 2.0 * t) + h12 * m2 * (t - 1.0)) * t * t;
+ } else {
+ // scale [x2, maxInLumi] to [y2, maxOutLumi] using Hermite interp
+ float t = (nits - x2) / h23;
+ nits = (y2 * (1.0 + 2.0 * t) + h23 * m2 * t) * (1.0 - t) * (1.0 - t) +
+ (maxOutLumi * (3.0 - 2.0 * t) + h23 * m3 * (t - 1.0)) * t * t;
+ }
+ }
+
+ // convert back to [0.0, 1.0]
+ return nits / maxOutLumi;
+ }
+
+ vec3 ToneMap(const vec3 color) {
+ return vec3(ToneMapChannel(color.r), ToneMapChannel(color.g),
+ ToneMapChannel(color.b));
+ }
+ )__SHADER__";
+ } else {
+ fs << R"__SHADER__(
+ vec3 ToneMap(const vec3 color) {
+ return color;
+ }
+ )__SHADER__";
}
}
fs << "void main(void) {" << indent;
if (needs.isTexturing()) {
fs << "gl_FragColor = texture2D(sampler, outTexCoords);";
+ if (needs.isY410BT2020()) {
+ fs << "gl_FragColor.rgb = convertY410BT2020(gl_FragColor.rgb);";
+ }
} else {
fs << "gl_FragColor.rgb = color.rgb;";
fs << "gl_FragColor.a = 1.0;";
@@ -274,7 +406,10 @@
// avoid divide by 0 by adding 0.5/256 to the alpha channel
fs << "gl_FragColor.rgb = gl_FragColor.rgb / (gl_FragColor.a + 0.0019);";
}
- fs << "vec4 transformed = colorMatrix * vec4(EOTF(gl_FragColor.rgb), 1);";
+ fs << "vec4 transformed = colorMatrix * vec4(ToneMap(EOTF(gl_FragColor.rgb)), 1);";
+ // the transformation from a wider colorspace to a narrower one can
+ // result in >1.0 or <0.0 pixel values
+ fs << "transformed.rgb = clamp(transformed.rgb, 0.0, 1.0);";
// We assume the last row is always {0,0,0,1} and we skip the division by w
fs << "gl_FragColor.rgb = OETF(transformed.rgb);";
if (!needs.isOpaque() && needs.isPremultiplied()) {