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path: root/libs/renderengine/skia/filters/LinearEffect.cpp
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Diffstat (limited to 'libs/renderengine/skia/filters/LinearEffect.cpp')
-rw-r--r--libs/renderengine/skia/filters/LinearEffect.cpp478
1 files changed, 478 insertions, 0 deletions
diff --git a/libs/renderengine/skia/filters/LinearEffect.cpp b/libs/renderengine/skia/filters/LinearEffect.cpp
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+++ b/libs/renderengine/skia/filters/LinearEffect.cpp
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+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LinearEffect.h"
+
+#define ATRACE_TAG ATRACE_TAG_GRAPHICS
+
+#include <SkString.h>
+#include <utils/Trace.h>
+
+#include <optional>
+
+#include "log/log.h"
+#include "math/mat4.h"
+#include "system/graphics-base-v1.0.h"
+#include "ui/ColorSpace.h"
+
+namespace android {
+namespace renderengine {
+namespace skia {
+
+static void generateEOTF(ui::Dataspace dataspace, SkString& 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_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;
+ }
+}
+
+static void generateXYZTransforms(SkString& shader) {
+ shader.append(R"(
+ uniform float4x4 in_rgbToXyz;
+ uniform float4x4 in_xyzToRgb;
+ float3 ToXYZ(float3 rgb) {
+ return clamp((in_rgbToXyz * float4(rgb, 1.0)).rgb, 0.0, 1.0);
+ }
+
+ float3 ToRGB(float3 xyz) {
+ return clamp((in_xyzToRgb * float4(xyz, 1.0)).rgb, 0.0, 1.0);
+ }
+ )");
+}
+
+// Conversion from relative light to absolute light (maps from [0, 1] to [0, maxNits])
+static void generateLuminanceScalesForOOTF(ui::Dataspace inputDataspace, SkString& 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:
+ shader.append(R"(
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * 1000.0 * pow(xyz.y, 0.2);
+ }
+ )");
+ break;
+ default:
+ shader.append(R"(
+ float3 ScaleLuminance(float3 xyz) {
+ return xyz * in_inputMaxLuminance;
+ }
+ )");
+ break;
+ }
+}
+
+static void generateToneMapInterpolation(ui::Dataspace inputDataspace,
+ ui::Dataspace outputDataspace, SkString& shader) {
+ switch (inputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ case HAL_DATASPACE_TRANSFER_HLG:
+ switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ shader.append(R"(
+ float3 ToneMap(float3 xyz) {
+ return xyz;
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_HLG:
+ // PQ has a wider luminance range (10,000 nits vs. 1,000 nits) than HLG, so
+ // we'll clamp the luminance range in case we're mapping from PQ input to HLG
+ // output.
+ shader.append(R"(
+ float3 ToneMap(float3 xyz) {
+ return clamp(xyz, 0.0, 1000.0);
+ }
+ )");
+ break;
+ default:
+ // Here we're mapping from HDR to SDR content, so interpolate using a Hermitian
+ // polynomial onto the smaller luminance range.
+ shader.append(R"(
+ float3 ToneMap(float3 xyz) {
+ float maxInLumi = in_inputMaxLuminance;
+ float maxOutLumi = in_displayMaxLuminance;
+
+ float nits = xyz.y;
+
+ // if the max input luminance is less than what we can output then
+ // no tone mapping is needed as all color values will be in range.
+ if (maxInLumi <= maxOutLumi) {
+ return xyz;
+ } else {
+
+ // three control points
+ const float x0 = 10.0;
+ const float y0 = 17.0;
+ float x1 = maxOutLumi * 0.75;
+ float y1 = x1;
+ float x2 = x1 + (maxInLumi - x1) / 2.0;
+ float y2 = y1 + (maxOutLumi - y1) * 0.75;
+
+ // horizontal distances between the last three control points
+ float h12 = x2 - x1;
+ float h23 = maxInLumi - x2;
+ // tangents at the last three control points
+ float m1 = (y2 - y1) / h12;
+ float m3 = (maxOutLumi - y2) / h23;
+ float m2 = (m1 + m3) / 2.0;
+
+ if (nits < x0) {
+ // scale [0.0, x0] to [0.0, y0] linearly
+ float slope = y0 / x0;
+ return xyz * slope;
+ } else if (nits < x1) {
+ // scale [x0, x1] to [y0, y1] linearly
+ 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;
+ }
+ }
+
+ // color.y is greater than x0 and is thus non-zero
+ return xyz * (nits / xyz.y);
+ }
+ )");
+ break;
+ }
+ break;
+ default:
+ switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ case HAL_DATASPACE_TRANSFER_HLG:
+ // Map from SDR onto an HDR output buffer
+ // Here we use a polynomial curve to map from [0, displayMaxLuminance] onto
+ // [0, maxOutLumi] which is hard-coded to be 3000 nits.
+ shader.append(R"(
+ float3 ToneMap(float3 xyz) {
+ const float maxOutLumi = 3000.0;
+
+ const float x0 = 5.0;
+ const float y0 = 2.5;
+ float x1 = in_displayMaxLuminance * 0.7;
+ float y1 = maxOutLumi * 0.15;
+ float x2 = in_displayMaxLuminance * 0.9;
+ float y2 = maxOutLumi * 0.45;
+ float x3 = in_displayMaxLuminance;
+ float y3 = maxOutLumi;
+
+ float c1 = y1 / 3.0;
+ float c2 = y2 / 2.0;
+ float c3 = y3 / 1.5;
+
+ float nits = xyz.y;
+
+ if (nits <= x0) {
+ // scale [0.0, x0] to [0.0, y0] linearly
+ float slope = y0 / x0;
+ return xyz * slope;
+ } else if (nits <= x1) {
+ // scale [x0, x1] to [y0, y1] using a curve
+ float t = (nits - x0) / (x1 - x0);
+ nits = (1.0 - t) * (1.0 - t) * y0 + 2.0 * (1.0 - t) * t * c1 + t * t * y1;
+ } else if (nits <= x2) {
+ // scale [x1, x2] to [y1, y2] using a curve
+ float t = (nits - x1) / (x2 - x1);
+ nits = (1.0 - t) * (1.0 - t) * y1 + 2.0 * (1.0 - t) * t * c2 + t * t * y2;
+ } else {
+ // scale [x2, x3] to [y2, y3] using a curve
+ float t = (nits - x2) / (x3 - x2);
+ nits = (1.0 - t) * (1.0 - t) * y2 + 2.0 * (1.0 - t) * t * c3 + t * t * y3;
+ }
+
+ // xyz.y is greater than x0 and is thus non-zero
+ return xyz * (nits / xyz.y);
+ }
+ )");
+ break;
+ default:
+ // For completeness, this is tone-mapping from SDR to SDR, where this is just a
+ // no-op.
+ shader.append(R"(
+ float3 ToneMap(float3 xyz) {
+ return xyz;
+ }
+ )");
+ break;
+ }
+ break;
+ }
+}
+
+// Normalizes from absolute light back to relative light (maps from [0, maxNits] back to [0, 1])
+static void generateLuminanceNormalizationForOOTF(ui::Dataspace outputDataspace, SkString& shader) {
+ switch (outputDataspace & HAL_DATASPACE_TRANSFER_MASK) {
+ case HAL_DATASPACE_TRANSFER_ST2084:
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / 10000.0;
+ }
+ )");
+ break;
+ case HAL_DATASPACE_TRANSFER_HLG:
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / 1000.0 * pow(xyz.y / 1000.0, -0.2 / 1.2);
+ }
+ )");
+ break;
+ default:
+ shader.append(R"(
+ float3 NormalizeLuminance(float3 xyz) {
+ return xyz / in_displayMaxLuminance;
+ }
+ )");
+ break;
+ }
+}
+
+static void generateOOTF(ui::Dataspace inputDataspace, ui::Dataspace outputDataspace,
+ SkString& shader) {
+ // Input uniforms
+ shader.append(R"(
+ uniform float in_displayMaxLuminance;
+ uniform float in_inputMaxLuminance;
+ )");
+
+ generateLuminanceScalesForOOTF(inputDataspace, shader);
+ generateToneMapInterpolation(inputDataspace, outputDataspace, shader);
+ generateLuminanceNormalizationForOOTF(outputDataspace, shader);
+
+ shader.append(R"(
+ float3 OOTF(float3 xyz) {
+ return NormalizeLuminance(ToneMap(ScaleLuminance(xyz)));
+ }
+ )");
+}
+
+static void generateOETF(ui::Dataspace dataspace, SkString& 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_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;
+ }
+}
+
+static void generateEffectiveOOTF(bool undoPremultipliedAlpha, SkString& shader) {
+ shader.append(R"(
+ uniform shader input;
+ half4 main(float2 xy) {
+ float4 c = float4(sample(input, xy));
+ )");
+ if (undoPremultipliedAlpha) {
+ shader.append(R"(
+ c.rgb = c.rgb / (c.a + 0.0019);
+ )");
+ }
+ shader.append(R"(
+ c.rgb = OETF(ToRGB(OOTF(ToXYZ(EOTF(c.rgb)))));
+ )");
+ if (undoPremultipliedAlpha) {
+ shader.append(R"(
+ c.rgb = c.rgb * (c.a + 0.0019);
+ )");
+ }
+ shader.append(R"(
+ return c;
+ }
+ )");
+}
+static ColorSpace toColorSpace(ui::Dataspace dataspace) {
+ switch (dataspace & HAL_DATASPACE_STANDARD_MASK) {
+ case HAL_DATASPACE_STANDARD_BT709:
+ return ColorSpace::sRGB();
+ break;
+ case HAL_DATASPACE_STANDARD_DCI_P3:
+ return ColorSpace::DisplayP3();
+ break;
+ case HAL_DATASPACE_STANDARD_BT2020:
+ return ColorSpace::BT2020();
+ break;
+ default:
+ return ColorSpace::sRGB();
+ break;
+ }
+}
+
+sk_sp<SkRuntimeEffect> buildRuntimeEffect(const LinearEffect& linearEffect) {
+ ATRACE_CALL();
+ SkString shaderString;
+ generateEOTF(linearEffect.inputDataspace, shaderString);
+ generateXYZTransforms(shaderString);
+ generateOOTF(linearEffect.inputDataspace, linearEffect.outputDataspace, shaderString);
+ generateOETF(linearEffect.outputDataspace, shaderString);
+ generateEffectiveOOTF(linearEffect.undoPremultipliedAlpha, shaderString);
+
+ auto [shader, error] = SkRuntimeEffect::MakeForShader(shaderString);
+ if (!shader) {
+ LOG_ALWAYS_FATAL("LinearColorFilter construction error: %s", error.c_str());
+ }
+ return shader;
+}
+
+sk_sp<SkShader> createLinearEffectShader(sk_sp<SkShader> shader, const LinearEffect& linearEffect,
+ sk_sp<SkRuntimeEffect> runtimeEffect,
+ const mat4& colorTransform, float maxDisplayLuminance,
+ float maxLuminance) {
+ ATRACE_CALL();
+ SkRuntimeShaderBuilder effectBuilder(runtimeEffect);
+
+ effectBuilder.child("input") = shader;
+
+ if (linearEffect.inputDataspace == linearEffect.outputDataspace) {
+ effectBuilder.uniform("in_rgbToXyz") = mat4();
+ effectBuilder.uniform("in_xyzToRgb") = colorTransform;
+ } else {
+ ColorSpace inputColorSpace = toColorSpace(linearEffect.inputDataspace);
+ ColorSpace outputColorSpace = toColorSpace(linearEffect.outputDataspace);
+
+ effectBuilder.uniform("in_rgbToXyz") = mat4(inputColorSpace.getRGBtoXYZ());
+ effectBuilder.uniform("in_xyzToRgb") =
+ colorTransform * mat4(outputColorSpace.getXYZtoRGB());
+ }
+
+ effectBuilder.uniform("in_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
+ effectBuilder.uniform("in_inputMaxLuminance") =
+ maxLuminance > 0 ? maxLuminance : maxDisplayLuminance;
+ return effectBuilder.makeShader(nullptr, false);
+}
+
+} // namespace skia
+} // namespace renderengine
+} // namespace android \ No newline at end of file
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-12 17:02:01 +0000