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gamma_expansion_effect_test.cpp
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gamma_expansion_effect_test.cpp
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// Unit tests for GammaExpansionEffect.
#include <epoxy/gl.h>
#include <math.h>
#include "gamma_expansion_effect.h"
#include "gtest/gtest.h"
#include "gtest/gtest-message.h"
#include "test_util.h"
namespace movit {
TEST(GammaExpansionEffectTest, sRGB_KeyValues) {
float data[] = {
0.0f, 1.0f,
0.040f, 0.041f, // On either side of the discontinuity.
};
float expected_data[] = {
0.0f, 1.0f,
0.00309f, 0.00317f,
};
float out_data[4];
EffectChainTester tester(data, 2, 2, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_sRGB);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
expect_equal(expected_data, out_data, 2, 2);
}
TEST(GammaExpansionEffectTest, sRGB_RampAlwaysIncreases) {
float data[256], out_data[256];
for (unsigned i = 0; i < 256; ++i) {
data[i] = i / 255.0f;
}
EffectChainTester tester(data, 256, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_sRGB);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
for (unsigned i = 1; i < 256; ++i) {
EXPECT_GT(out_data[i], out_data[i - 1])
<< "No increase between " << i-1 << " and " << i;
}
}
TEST(GammaExpansionEffectTest, sRGB_AlphaIsUnchanged) {
float data[] = {
0.0f, 0.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.25f,
0.0f, 0.0f, 0.0f, 0.5f,
0.0f, 0.0f, 0.0f, 0.75f,
0.0f, 0.0f, 0.0f, 1.0f,
};
float out_data[5 * 4];
EffectChainTester tester(data, 5, 1, FORMAT_RGBA_POSTMULTIPLIED_ALPHA, COLORSPACE_sRGB, GAMMA_sRGB);
tester.run(out_data, GL_RGBA, COLORSPACE_sRGB, GAMMA_LINEAR);
expect_equal(data, out_data, 5, 1);
}
TEST(GammaExpansionEffectTest, sRGB_Accuracy) {
float data[256], expected_data[256], out_data[256];
for (int i = 0; i < 256; ++i) {
double x = i / 255.0;
data[i] = x;
expected_data[i] = srgb_to_linear(x);
}
EffectChainTester tester(data, 256, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_sRGB, GL_RGBA32F);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
// Accuracy limits; for comparison, limits for a straightforward ALU solution
// (using a branch and pow()) in parenthesis, used as a “high anchor” to
// indicate limitations of float arithmetic etc.:
//
// Maximum absolute error: 0.1% of max energy (0.051%)
// Maximum relative error: 2.5% of correct answer (0.093%)
// 25% of difference to next pixel level (6.18%)
// Allowed RMS error: 0.0001 (0.000010)
//
test_accuracy(expected_data, out_data, 256, 1e-3, 0.025, 0.25, 1e-4);
}
TEST(GammaExpansionEffectTest, Rec709_KeyValues) {
float data[] = {
0.0f, 1.0f,
0.080f, 0.082f, // On either side of the discontinuity.
};
float expected_data[] = {
0.0f, 1.0f,
0.017778f, 0.018167f,
};
float out_data[4];
EffectChainTester tester(data, 2, 2, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_REC_709);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
expect_equal(expected_data, out_data, 2, 2);
}
TEST(GammaExpansionEffectTest, Rec709_RampAlwaysIncreases) {
float data[256], out_data[256];
for (unsigned i = 0; i < 256; ++i) {
data[i] = i / 255.0f;
}
EffectChainTester tester(data, 256, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_REC_709);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
for (unsigned i = 1; i < 256; ++i) {
EXPECT_GT(out_data[i], out_data[i - 1])
<< "No increase between " << i-1 << " and " << i;
}
}
TEST(GammaExpansionEffectTest, Rec709_AlphaIsUnchanged) {
float data[] = {
0.0f, 0.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.25f,
0.0f, 0.0f, 0.0f, 0.5f,
0.0f, 0.0f, 0.0f, 0.75f,
0.0f, 0.0f, 0.0f, 1.0f,
};
float out_data[5 * 4];
EffectChainTester tester(data, 5, 1, FORMAT_RGBA_POSTMULTIPLIED_ALPHA, COLORSPACE_sRGB, GAMMA_REC_709);
tester.run(out_data, GL_RGBA, COLORSPACE_sRGB, GAMMA_LINEAR);
expect_equal(data, out_data, 5, 1);
}
TEST(GammaExpansionEffectTest, Rec709_Accuracy) {
float data[256], expected_data[256], out_data[256];
for (int i = 0; i < 256; ++i) {
double x = i / 255.0;
data[i] = x;
// Rec. 2020, page 3.
if (x < 0.018 * 4.5) {
expected_data[i] = x / 4.5;
} else {
expected_data[i] = pow((x + 0.099) / 1.099, 1.0 / 0.45);
}
}
EffectChainTester tester(data, 256, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_REC_709, GL_RGBA32F);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
// Accuracy limits; for comparison, limits for a straightforward ALU solution
// (using a branch and pow()) in parenthesis, used as a “high anchor” to
// indicate limitations of float arithmetic etc.:
//
// Maximum absolute error: 0.1% of max energy (0.046%)
// Maximum relative error: 1.0% of correct answer (0.080%)
// 10% of difference to next pixel level (6.19%)
// Allowed RMS error: 0.0001 (0.000010)
//
test_accuracy(expected_data, out_data, 256, 1e-3, 0.01, 0.1, 1e-4);
}
// This test tests the same gamma ramp as Rec709_Accuracy, but with 10-bit
// input range and somewhat looser error bounds. (One could claim that this is
// already on the limit of what we can reasonably do with fp16 input, if you
// look at the local relative error.)
TEST(GammaExpansionEffectTest, Rec2020_10Bit_Accuracy) {
float data[1024], expected_data[1024], out_data[1024];
for (int i = 0; i < 1024; ++i) {
double x = i / 1023.0;
data[i] = x;
// Rec. 2020, page 3.
if (x < 0.018 * 4.5) {
expected_data[i] = x / 4.5;
} else {
expected_data[i] = pow((x + 0.099) / 1.099, 1.0 / 0.45);
}
}
EffectChainTester tester(data, 1024, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_REC_2020_10_BIT, GL_RGBA32F);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
// Accuracy limits; for comparison, limits for a straightforward ALU solution
// (using a branch and pow()) in parenthesis, used as a “high anchor” to
// indicate limitations of float arithmetic etc.:
//
// Maximum absolute error: 0.1% of max energy (0.036%)
// Maximum relative error: 1.0% of correct answer (0.064%)
// 30% of difference to next pixel level (24.9%)
// Allowed RMS error: 0.0001 (0.000005)
//
test_accuracy(expected_data, out_data, 1024, 1e-3, 0.01, 0.30, 1e-4);
}
TEST(GammaExpansionEffectTest, Rec2020_12BitIsVeryCloseToRec709) {
float data[256];
for (unsigned i = 0; i < 256; ++i) {
data[i] = i / 255.0f;
}
float out_data_709[256];
float out_data_2020[256];
EffectChainTester tester(data, 256, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_REC_709);
tester.run(out_data_709, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
EffectChainTester tester2(data, 256, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_REC_2020_12_BIT);
tester2.run(out_data_2020, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
double sqdiff = 0.0;
for (unsigned i = 0; i < 256; ++i) {
EXPECT_NEAR(out_data_709[i], out_data_2020[i], 1e-3);
sqdiff += (out_data_709[i] - out_data_2020[i]) * (out_data_709[i] - out_data_2020[i]);
}
EXPECT_GT(sqdiff, 1e-6);
}
// The fp16 _input_ provided by FlatInput is not enough to distinguish between
// all of the possible 12-bit input values (every other level translates to the
// same value). Thus, this test has extremely loose bounds; if we ever decide
// to start supporting fp32, we should re-run this and tighten them a lot.
TEST(GammaExpansionEffectTest, Rec2020_12Bit_Inaccuracy) {
float data[4096], expected_data[4096], out_data[4096];
for (int i = 0; i < 4096; ++i) {
double x = i / 4095.0;
data[i] = x;
// Rec. 2020, page 3.
if (x < 0.0181 * 4.5) {
expected_data[i] = x / 4.5;
} else {
expected_data[i] = pow((x + 0.0993) / 1.0993, 1.0/0.45);
}
}
EffectChainTester tester(data, 4096, 1, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_REC_2020_12_BIT, GL_RGBA32F);
tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
// Accuracy limits; for comparison, limits for a straightforward ALU solution
// (using a branch and pow()) in parenthesis, used as a “high anchor” to
// indicate limitations of float arithmetic etc.:
//
// Maximum absolute error: 0.1% of max energy (0.050%)
// Maximum relative error: 1.0% of correct answer (0.050%)
// 250% of difference to next pixel level (100.00%)
// Allowed RMS error: 0.0001 (0.000003)
//
test_accuracy(expected_data, out_data, 4096, 1e-3, 0.01, 2.50, 1e-4);
}
} // namespace movit