Support different chroma positioning for Cb and Cr. The test is slightly shaky, so...
authorSteinar H. Gunderson <sgunderson@bigfoot.com>
Tue, 16 Oct 2012 23:34:22 +0000 (01:34 +0200)
committerSteinar H. Gunderson <sgunderson@bigfoot.com>
Tue, 16 Oct 2012 23:34:22 +0000 (01:34 +0200)
ycbcr_input.cpp
ycbcr_input.frag
ycbcr_input.h
ycbcr_input_test.cpp

index 374237e..fe36eb0 100644 (file)
@@ -253,12 +253,20 @@ std::string YCbCrInput::output_fragment_shader()
                scale[0], scale[1], scale[2]);
        frag_shader += buf;
 
-       float chroma_offset_x = compute_chroma_offset(
-               ycbcr_format.chroma_x_position, ycbcr_format.chroma_subsampling_x, widths[1]);
-       float chroma_offset_y = compute_chroma_offset(
-               ycbcr_format.chroma_y_position, ycbcr_format.chroma_subsampling_y, heights[1]);
-       sprintf(buf, "const vec2 PREFIX(chroma_offset) = vec2(%.8f, %.8f);\n",
-               chroma_offset_x, chroma_offset_y);
+       float cb_offset_x = compute_chroma_offset(
+               ycbcr_format.cb_x_position, ycbcr_format.chroma_subsampling_x, widths[1]);
+       float cb_offset_y = compute_chroma_offset(
+               ycbcr_format.cb_y_position, ycbcr_format.chroma_subsampling_y, heights[1]);
+       sprintf(buf, "const vec2 PREFIX(cb_offset) = vec2(%.8f, %.8f);\n",
+               cb_offset_x, cb_offset_y);
+       frag_shader += buf;
+
+       float cr_offset_x = compute_chroma_offset(
+               ycbcr_format.cr_x_position, ycbcr_format.chroma_subsampling_x, widths[2]);
+       float cr_offset_y = compute_chroma_offset(
+               ycbcr_format.cr_y_position, ycbcr_format.chroma_subsampling_y, heights[2]);
+       sprintf(buf, "const vec2 PREFIX(cr_offset) = vec2(%.8f, %.8f);\n",
+               cr_offset_x, cr_offset_y);
        frag_shader += buf;
 
        frag_shader += read_file("ycbcr_input.frag");
index 13e44b0..8da8256 100644 (file)
@@ -10,8 +10,8 @@ vec4 FUNCNAME(vec2 tc) {
 
        vec3 ycbcr;
        ycbcr.x = texture2D(PREFIX(tex_y), tc).x;
-       ycbcr.y = texture2D(PREFIX(tex_cb), tc + PREFIX(chroma_offset)).x;
-       ycbcr.z = texture2D(PREFIX(tex_cr), tc + PREFIX(chroma_offset)).x;
+       ycbcr.y = texture2D(PREFIX(tex_cb), tc + PREFIX(cb_offset)).x;
+       ycbcr.z = texture2D(PREFIX(tex_cr), tc + PREFIX(cr_offset)).x;
 
        ycbcr -= PREFIX(offset);
        ycbcr *= PREFIX(scale);
index 6c33cec..fba5588 100644 (file)
@@ -22,7 +22,8 @@ struct YCbCrFormat {
 
        // Positioning of the chroma samples. MPEG-1 and JPEG is (0.5, 0.5);
        // MPEG-2 and newer typically are (0.0, 0.5).
-       float chroma_x_position, chroma_y_position;
+       float cb_x_position, cb_y_position;
+       float cr_x_position, cr_y_position;
 };
 
 class YCbCrInput : public Input {
index 7b2a6fd..5bd052b 100644 (file)
@@ -40,8 +40,10 @@ TEST(YCbCrInput, Simple444) {
        ycbcr_format.full_range = false;
        ycbcr_format.chroma_subsampling_x = 1;
        ycbcr_format.chroma_subsampling_y = 1;
-       ycbcr_format.chroma_x_position = 0.5f;
-       ycbcr_format.chroma_y_position = 0.5f;
+       ycbcr_format.cb_x_position = 0.5f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_x_position = 0.5f;
+       ycbcr_format.cr_y_position = 0.5f;
 
        YCbCrInput *input = new YCbCrInput(format, ycbcr_format, width, height);
        input->set_pixel_data(0, y);
@@ -92,8 +94,10 @@ TEST(YCbCrInput, FullRangeRec601) {
        ycbcr_format.full_range = true;
        ycbcr_format.chroma_subsampling_x = 1;
        ycbcr_format.chroma_subsampling_y = 1;
-       ycbcr_format.chroma_x_position = 0.5f;
-       ycbcr_format.chroma_y_position = 0.5f;
+       ycbcr_format.cb_x_position = 0.5f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_x_position = 0.5f;
+       ycbcr_format.cr_y_position = 0.5f;
 
        YCbCrInput *input = new YCbCrInput(format, ycbcr_format, width, height);
        input->set_pixel_data(0, y);
@@ -143,8 +147,10 @@ TEST(YCbCrInput, Rec709) {
        ycbcr_format.full_range = false;
        ycbcr_format.chroma_subsampling_x = 1;
        ycbcr_format.chroma_subsampling_y = 1;
-       ycbcr_format.chroma_x_position = 0.5f;
-       ycbcr_format.chroma_y_position = 0.5f;
+       ycbcr_format.cb_x_position = 0.5f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_x_position = 0.5f;
+       ycbcr_format.cr_y_position = 0.5f;
 
        YCbCrInput *input = new YCbCrInput(format, ycbcr_format, width, height);
        input->set_pixel_data(0, y);
@@ -202,8 +208,10 @@ TEST(YCbCrInput, Subsampling420) {
        ycbcr_format.full_range = false;
        ycbcr_format.chroma_subsampling_x = 2;
        ycbcr_format.chroma_subsampling_y = 2;
-       ycbcr_format.chroma_x_position = 0.5f;
-       ycbcr_format.chroma_y_position = 0.5f;
+       ycbcr_format.cb_x_position = 0.5f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_x_position = 0.5f;
+       ycbcr_format.cr_y_position = 0.5f;
 
        YCbCrInput *input = new YCbCrInput(format, ycbcr_format, width, height);
        input->set_pixel_data(0, y);
@@ -261,8 +269,10 @@ TEST(YCbCrInput, Subsampling420WithNonCenteredSamples) {
        ycbcr_format.full_range = false;
        ycbcr_format.chroma_subsampling_x = 2;
        ycbcr_format.chroma_subsampling_y = 2;
-       ycbcr_format.chroma_x_position = 0.0f;
-       ycbcr_format.chroma_y_position = 0.5f;
+       ycbcr_format.cb_x_position = 0.0f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_x_position = 0.0f;
+       ycbcr_format.cr_y_position = 0.5f;
 
        YCbCrInput *input = new YCbCrInput(format, ycbcr_format, width, height);
        input->set_pixel_data(0, y);
@@ -276,3 +286,74 @@ TEST(YCbCrInput, Subsampling420WithNonCenteredSamples) {
        // so we need some leeway.
        expect_equal(expected_data, out_data, width, height, 0.01, 0.001);
 }
+
+// Yes, some 4:2:2 formats actually have this craziness.
+TEST(YCbCrInput, DifferentCbAndCrPositioning) {
+       const int width = 4;
+       const int height = 4;
+
+       unsigned char y[width * height] = {
+               126, 126, 126, 126,
+               126, 126, 126, 126,
+               126, 126, 126, 126,
+               126, 126, 126, 126,
+       };
+       unsigned char cb[(width/2) * height] = {
+               64, 128,
+               128, 192,
+               128, 128,
+               128, 128,
+       };
+       unsigned char cr[(width/2) * height] = {
+               48, 128,
+               128, 208,
+               128, 128,
+               128, 128,
+       };
+
+       // Chroma samples in this csae are always co-sited with a luma sample;
+       // their associated color values and position are marked off in comments.
+       float expected_data_blue[width * height] = {
+                  0.000 /* 0.0 */, 0.250,           0.500 /* 0.5 */, 0.500, 
+                  0.500 /* 0.5 */, 0.750,           1.000 /* 1.0 */, 1.000, 
+                  0.500 /* 0.5 */, 0.500,           0.500 /* 0.5 */, 0.500, 
+                  0.500 /* 0.5 */, 0.500,           0.500 /* 0.5 */, 0.500, 
+       };
+       float expected_data_red[width * height] = {
+                  0.000,           0.000 /* 0.0 */, 0.250,           0.500 /* 0.5 */, 
+                  0.500,           0.500 /* 0.5 */, 0.750,           1.000 /* 1.0 */, 
+                  0.500,           0.500 /* 0.5 */, 0.500,           0.500 /* 0.5 */, 
+                  0.500,           0.500 /* 0.5 */, 0.500,           0.500 /* 0.5 */, 
+       };
+       float out_data[width * height];
+
+       EffectChainTester tester(NULL, width, height);
+
+       ImageFormat format;
+       format.color_space = COLORSPACE_sRGB;
+       format.gamma_curve = GAMMA_sRGB;
+
+       YCbCrFormat ycbcr_format;
+       ycbcr_format.luma_coefficients = YCBCR_REC_601;
+       ycbcr_format.full_range = false;
+       ycbcr_format.chroma_subsampling_x = 2;
+       ycbcr_format.chroma_subsampling_y = 1;
+       ycbcr_format.cb_x_position = 0.0f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_x_position = 1.0f;
+       ycbcr_format.cr_y_position = 0.5f;
+
+       YCbCrInput *input = new YCbCrInput(format, ycbcr_format, width, height);
+       input->set_pixel_data(0, y);
+       input->set_pixel_data(1, cb);
+       input->set_pixel_data(2, cr);
+       tester.get_chain()->add_input(input);
+
+       // Y'CbCr isn't 100% accurate (the input values are rounded),
+       // so we need some leeway.
+       tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_sRGB);
+       expect_equal(expected_data_red, out_data, width, height, 0.02, 0.002);
+
+       tester.run(out_data, GL_BLUE, COLORSPACE_sRGB, GAMMA_sRGB);
+       expect_equal(expected_data_blue, out_data, width, height, 0.01, 0.001);
+}