X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=resample_effect_test.cpp;fp=resample_effect_test.cpp;h=462f5c9c1f6d6751d874f5c5cb67e55d243f468c;hb=fb92a4e217a92ecf83b7812cc6933f6f3048b752;hp=0000000000000000000000000000000000000000;hpb=9e62fbe2ac764479c449472d8bda52ac4df0de91;p=movit

diff --git a/resample_effect_test.cpp b/resample_effect_test.cpp
new file mode 100644
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--- /dev/null
+++ b/resample_effect_test.cpp
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+// Unit tests for ResampleEffect.
+
+#include "test_util.h"
+#include "gtest/gtest.h"
+#include "resample_effect.h"
+#include "flat_input.h"
+
+namespace {
+
+float sinc(float x)
+{
+	return sin(M_PI * x) / (M_PI * x);
+}
+
+float lanczos(float x, float a)
+{
+	if (fabs(x) >= a) {
+		return 0.0f;
+	} else {
+		return sinc(x) * sinc(x / a);
+	}
+}
+
+}  // namespace
+
+TEST(ResampleEffectTest, IdentityTransformDoesNothing) {
+	const int size = 4;
+
+	float data[size * size] = {
+		0.0, 1.0, 0.0, 1.0,
+		0.0, 1.0, 1.0, 0.0,
+		0.0, 0.5, 1.0, 0.5,
+		0.0, 0.0, 0.0, 0.0,
+	};
+	float out_data[size * size];
+
+	EffectChainTester tester(data, size, size, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
+	Effect *resample_effect = tester.get_chain()->add_effect(new ResampleEffect());
+	ASSERT_TRUE(resample_effect->set_int("width", 4));
+	ASSERT_TRUE(resample_effect->set_int("height", 4));
+	tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	expect_equal(data, out_data, size, size);
+}
+
+TEST(ResampleEffectTest, UpscaleByTwoGetsCorrectPixelCenters) {
+	const int size = 5;
+
+	float data[size * size] = {
+		0.0, 0.0, 0.0, 0.0, 0.0,
+		0.0, 0.0, 0.0, 0.0, 0.0,
+		0.0, 0.0, 1.0, 0.0, 0.0,
+		0.0, 0.0, 0.0, 0.0, 0.0,
+		0.0, 0.0, 0.0, 0.0, 0.0,
+	};
+	float expected_data[size * size * 4], out_data[size * size * 4];
+
+	for (int y = 0; y < size * 2; ++y) {
+		for (int x = 0; x < size * 2; ++x) {
+			float weight = lanczos((x - size + 0.5f) * 0.5f, 3.0f);
+			weight *= lanczos((y - size + 0.5f) * 0.5f, 3.0f);
+			expected_data[y * (size * 2) + x] = weight;
+		}
+	}
+
+	EffectChainTester tester(NULL, size * 2, size * 2, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	ImageFormat format;
+	format.color_space = COLORSPACE_sRGB;
+	format.gamma_curve = GAMMA_LINEAR;
+
+	FlatInput *input = new FlatInput(format, FORMAT_GRAYSCALE, GL_FLOAT, size, size);
+	input->set_pixel_data(data);
+	tester.get_chain()->add_input(input);
+
+	Effect *resample_effect = tester.get_chain()->add_effect(new ResampleEffect());
+	ASSERT_TRUE(resample_effect->set_int("width", size * 2));
+	ASSERT_TRUE(resample_effect->set_int("height", size * 2));
+	tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	expect_equal(expected_data, out_data, size * 2, size * 2);
+}
+
+TEST(ResampleEffectTest, DownscaleByTwoGetsCorrectPixelCenters) {
+	const int size = 5;
+
+	// This isn't a perfect dot, since the Lanczos filter has a slight
+	// sharpening effect; the most important thing is that we have kept
+	// the texel center right (everything is nicely symmetric).
+	// The approximate magnitudes have been checked against ImageMagick.
+	float expected_data[size * size] = {
+		 0.0045, -0.0067, -0.0598, -0.0067,  0.0045, 
+		-0.0067,  0.0099,  0.0886,  0.0099, -0.0067, 
+		-0.0598,  0.0886,  0.7930,  0.0886, -0.0598, 
+		-0.0067,  0.0099,  0.0886,  0.0099, -0.0067, 
+		 0.0045, -0.0067, -0.0598, -0.0067,  0.0045, 
+	};
+	float data[size * size * 4], out_data[size * size];
+
+	for (int y = 0; y < size * 2; ++y) {
+		for (int x = 0; x < size * 2; ++x) {
+			float weight = lanczos((x - size + 0.5f) * 0.5f, 3.0f);
+			weight *= lanczos((y - size + 0.5f) * 0.5f, 3.0f);
+			data[y * (size * 2) + x] = weight;
+		}
+	}
+
+	EffectChainTester tester(NULL, size, size, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	ImageFormat format;
+	format.color_space = COLORSPACE_sRGB;
+	format.gamma_curve = GAMMA_LINEAR;
+
+	FlatInput *input = new FlatInput(format, FORMAT_GRAYSCALE, GL_FLOAT, size * 2, size * 2);
+	input->set_pixel_data(data);
+	tester.get_chain()->add_input(input);
+
+	Effect *resample_effect = tester.get_chain()->add_effect(new ResampleEffect());
+	ASSERT_TRUE(resample_effect->set_int("width", size));
+	ASSERT_TRUE(resample_effect->set_int("height", size));
+	tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	expect_equal(expected_data, out_data, size, size);
+}
+
+TEST(ResampleEffectTest, UpscaleByThreeGetsCorrectPixelCenters) {
+	const int size = 5;
+
+	float data[size * size] = {
+		0.0, 0.0, 0.0, 0.0, 0.0,
+		0.0, 0.0, 0.0, 0.0, 0.0,
+		0.0, 0.0, 1.0, 0.0, 0.0,
+		0.0, 0.0, 0.0, 0.0, 0.0,
+		0.0, 0.0, 0.0, 0.0, 0.0,
+	};
+	float out_data[size * size * 9];
+
+	EffectChainTester tester(NULL, size * 3, size * 3, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	ImageFormat format;
+	format.color_space = COLORSPACE_sRGB;
+	format.gamma_curve = GAMMA_LINEAR;
+
+	FlatInput *input = new FlatInput(format, FORMAT_GRAYSCALE, GL_FLOAT, size, size);
+	input->set_pixel_data(data);
+	tester.get_chain()->add_input(input);
+
+	Effect *resample_effect = tester.get_chain()->add_effect(new ResampleEffect());
+	ASSERT_TRUE(resample_effect->set_int("width", size * 3));
+	ASSERT_TRUE(resample_effect->set_int("height", size * 3));
+	tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	// We only bother checking that the middle pixel is still correct,
+	// and that symmetry holds.
+	EXPECT_FLOAT_EQ(1.0, out_data[7 * (size * 3) + 7]);
+	for (unsigned y = 0; y < size * 3; ++y) {
+		for (unsigned x = 0; x < size * 3; ++x) {
+			EXPECT_FLOAT_EQ(out_data[y * (size * 3) + x], out_data[(size * 3 - y - 1) * (size * 3) + x]);
+			EXPECT_FLOAT_EQ(out_data[y * (size * 3) + x], out_data[y * (size * 3) + (size * 3 - x - 1)]);
+		}
+	}
+}