From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sun, 29 Dec 2013 22:55:57 +0000 (+0100)
Subject: Fix a bug where DeconvolutionSharpenEffect would forget one line of the kernel.
X-Git-Tag: 1.0~104
X-Git-Url: https://git.sesse.net/?p=movit;a=commitdiff_plain;h=b5a446a44ee1f0379e8427f86f5dfa0d40bc0e60

Fix a bug where DeconvolutionSharpenEffect would forget one line of the kernel.

This manifested itself in that non-identity filters would start changing alpha
of solid images (since the kernel didn't sum up to one), which obviously isn't
good. Added a unit test to make sure it doesn't happen again.
---

diff --git a/deconvolution_sharpen_effect.frag b/deconvolution_sharpen_effect.frag
index 90ca3c1..4b4b18f 100644
--- a/deconvolution_sharpen_effect.frag
+++ b/deconvolution_sharpen_effect.frag
@@ -36,7 +36,7 @@ vec4 FUNCNAME(vec2 tc) {
 	// Case D: All other samples have four-way symmetry.
 	// (Actually we have eight-way, but since we are using normalized
 	// coordinates, we can't just flip x and y.)
-	for (int y = 1; y < R; ++y) {
+	for (int y = 1; y <= R; ++y) {
 		for (int x = 1; x <= R; ++x) {
 			vec4 sample = PREFIX(samples)[y * (R + 1) + x];
 			vec2 mirror_sample = vec2(sample.x, -sample.y);
diff --git a/deconvolution_sharpen_effect_test.cpp b/deconvolution_sharpen_effect_test.cpp
index 6980b3d..8daeb67 100644
--- a/deconvolution_sharpen_effect_test.cpp
+++ b/deconvolution_sharpen_effect_test.cpp
@@ -199,3 +199,35 @@ TEST(DeconvolutionSharpenEffectTest, NoiseAndCorrelationControlsReduceNoiseBoost
 	// Check that we didn't boost total energy (which in this case means the noise) more than 10%.
 	EXPECT_LT(sumsq_out, sumsq_in * 1.1f);
 }
+
+TEST(DeconvolutionSharpenEffectTest, CircularDeconvolutionKeepsAlpha) {
+	// Somewhat bigger, to make sure we are much bigger than the matrix size.
+	const int size = 32;
+
+	float data[size * size * 4];
+	float out_data[size * size];
+	float expected_alpha[size * size];
+
+	// Checkerbox pattern.
+	for (int y = 0; y < size; ++y) {
+		for (int x = 0; x < size; ++x) {
+			int c = (y ^ x) & 1;
+			data[(y * size + x) * 4 + 0] = c;
+			data[(y * size + x) * 4 + 1] = c;
+			data[(y * size + x) * 4 + 2] = c;
+			data[(y * size + x) * 4 + 3] = 1.0;
+			expected_alpha[y * size + x] = 1.0;
+		}
+	}
+
+	EffectChainTester tester(data, size, size, FORMAT_RGBA_POSTMULTIPLIED_ALPHA, COLORSPACE_sRGB, GAMMA_LINEAR);
+	Effect *deconvolution_effect = tester.get_chain()->add_effect(new DeconvolutionSharpenEffect());
+	ASSERT_TRUE(deconvolution_effect->set_int("matrix_size", 5));
+	ASSERT_TRUE(deconvolution_effect->set_float("circle_radius", 2.0f));
+	ASSERT_TRUE(deconvolution_effect->set_float("gaussian_radius", 0.0f));
+	ASSERT_TRUE(deconvolution_effect->set_float("correlation", 0.0001f));
+	ASSERT_TRUE(deconvolution_effect->set_float("noise", 0.0f));
+	tester.run(out_data, GL_ALPHA, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	expect_equal(expected_alpha, out_data, size, size);
+}