[babl] extensions: Add the Y'CbCr ITU-R BT.709 Color Space

[Téo Mazars <teom src gnome org>]

commit 45d0de90c68101faf5118e8a3d116ed6fd6bfb41
Author: Téo Mazars <teo mazars ensimag fr>
Date:   Wed Jun 26 23:00:05 2013 +0200

    extensions: Add the Y'CbCr ITU-R BT.709 Color Space
    
    A variation of the current Y'CbCr (BT.601 or 470?), needed downstream.

 extensions/Makefile.am |    4 +-
 extensions/ycbcr.c     |  258 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 261 insertions(+), 1 deletions(-)
---
diff --git a/extensions/Makefile.am b/extensions/Makefile.am
index dca87c0..3954739 100644
--- a/extensions/Makefile.am
+++ b/extensions/Makefile.am
@@ -31,7 +31,8 @@ ext_LTLIBRARIES = \
        sse2-float.la   \
        sse2-int8.la    \
        sse2-int16.la   \
-       two-table.la
+       two-table.la    \
+       ycbcr.la
 
 cairo_la_SOURCES = cairo.c cairo-tables.h
 CIE_la_SOURCES = CIE.c
@@ -48,6 +49,7 @@ sse2_float_la_SOURCES = sse2-float.c
 sse2_int8_la_SOURCES = sse2-int8.c
 sse2_int16_la_SOURCES = sse2-int16.c
 two_table_la_SOURCES = two-table.c two-table-tables.h
+ycbcr_la_SOURCES = ycbcr.c
 float_la_SOURCES = float.c
 fast_float_la_SOURCES = fast-float.c
 
diff --git a/extensions/ycbcr.c b/extensions/ycbcr.c
new file mode 100644
index 0000000..11db563
--- /dev/null
+++ b/extensions/ycbcr.c
@@ -0,0 +1,258 @@
+/* babl - dynamically extendable universal pixel conversion library.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <math.h>
+#include <string.h>
+
+#include "babl.h"
+#include "base/util.h"
+
+
+static void components  (void);
+static void models      (void);
+static void conversions (void);
+static void formats     (void);
+
+int init (void);
+
+
+int
+init (void)
+{
+  components ();
+  models ();
+  conversions ();
+  formats ();
+
+  return 0;
+}
+
+
+static void
+components (void)
+{
+  babl_component_new ("alpha", NULL);
+}
+
+
+static void
+models (void)
+{
+  babl_model_new (
+    "name", "Y'CbCr709",
+    babl_component ("Y'"),
+    babl_component ("Cb"),
+    babl_component ("Cr"),
+    NULL);
+
+  babl_model_new (
+    "name", "Y'CbCrA709",
+    babl_component ("Y'"),
+    babl_component ("Cb"),
+    babl_component ("Cr"),
+    babl_component ("alpha"),
+    NULL);
+}
+
+
+static long
+rgba_to_ycbcra709 (char *src,
+                   char *dst,
+                   long  n)
+{
+  while (n--)
+    {
+      double red   = ((double *) src)[0];
+      double green = ((double *) src)[1];
+      double blue  = ((double *) src)[2];
+      double alpha = ((double *) src)[3];
+
+      double luminance, cb, cr;
+
+      red   = linear_to_gamma_2_2 (red);
+      green = linear_to_gamma_2_2 (green);
+      blue  = linear_to_gamma_2_2 (blue);
+
+      luminance =  0.2126 * red + 0.7152 * green + 0.0722 * blue;
+      cb        =  (blue - luminance) / 1.8556;
+      cr        =  (red  - luminance) / 1.5748;
+
+      ((double *) dst)[0] = luminance;
+      ((double *) dst)[1] = cb;
+      ((double *) dst)[2] = cr;
+      ((double *) dst)[3] = alpha;
+
+      src += sizeof (double) * 4;
+      dst += sizeof (double) * 4;
+    }
+  return n;
+}
+
+
+static long
+rgba_to_ycbcr709 (char *src,
+                  char *dst,
+                  long  n)
+{
+  while (n--)
+    {
+      double red   = ((double *) src)[0];
+      double green = ((double *) src)[1];
+      double blue  = ((double *) src)[2];
+
+      double luminance, cb, cr;
+
+      red   = linear_to_gamma_2_2 (red);
+      green = linear_to_gamma_2_2 (green);
+      blue  = linear_to_gamma_2_2 (blue);
+
+      luminance =  0.2126 * red + 0.7152 * green + 0.0722 * blue;
+      cb        =  (blue - luminance) / 1.8556;
+      cr        =  (red  - luminance) / 1.5748;
+
+      ((double *) dst)[0] = luminance;
+      ((double *) dst)[1] = cb;
+      ((double *) dst)[2] = cr;
+
+      src += sizeof (double) * 4;
+      dst += sizeof (double) * 3;
+    }
+  return n;
+}
+
+
+static long
+ycbcra709_to_rgba (char *src,
+                char *dst,
+                long  n)
+{
+  while (n--)
+    {
+      double luminance = ((double *) src)[0];
+      double cb        = ((double *) src)[1];
+      double cr        = ((double *) src)[2];
+      double alpha     = ((double *) src)[3];
+
+      double red, green, blue;
+
+      red   = 1.0 * luminance + 0.0    * cb + 1.5748 * cr;
+      green = 1.0 * luminance - 0.1873 * cb - 0.4681 * cr;
+      blue  = 1.0 * luminance + 1.8556 * cb + 0.0    * cr;
+
+      red   = gamma_2_2_to_linear (red);
+      green = gamma_2_2_to_linear (green);
+      blue  = gamma_2_2_to_linear (blue);
+
+      ((double *) dst)[0] = red;
+      ((double *) dst)[1] = green;
+      ((double *) dst)[2] = blue;
+      ((double *) dst)[3] = alpha;
+
+      src += sizeof (double) * 4;
+      dst += sizeof (double) * 4;
+    }
+  return n;
+}
+
+
+static long
+ycbcr709_to_rgba (char *src,
+               char *dst,
+               long  n)
+{
+  while (n--)
+    {
+      double luminance = ((double *) src)[0];
+      double cb        = ((double *) src)[1];
+      double cr        = ((double *) src)[2];
+
+      double red, green, blue;
+
+      red   = 1.0 * luminance + 0.0    * cb + 1.5748 * cr;
+      green = 1.0 * luminance - 0.1873 * cb - 0.4681 * cr;
+      blue  = 1.0 * luminance + 1.8556 * cb + 0.0    * cr;
+
+      red   = gamma_2_2_to_linear (red);
+      green = gamma_2_2_to_linear (green);
+      blue  = gamma_2_2_to_linear (blue);
+
+      ((double *) dst)[0] = red;
+      ((double *) dst)[1] = green;
+      ((double *) dst)[2] = blue;
+      ((double *) dst)[3] = 1.0;
+
+      src += sizeof (double) * 3;
+      dst += sizeof (double) * 4;
+    }
+  return n;
+}
+
+
+static void
+conversions (void)
+{
+  babl_conversion_new (
+    babl_model ("RGBA"),
+    babl_model ("Y'CbCr709"),
+    "linear", rgba_to_ycbcr709,
+    NULL
+  );
+  babl_conversion_new (
+    babl_model ("RGBA"),
+    babl_model ("Y'CbCrA709"),
+    "linear", rgba_to_ycbcra709,
+    NULL
+  );
+  babl_conversion_new (
+    babl_model ("Y'CbCrA709"),
+    babl_model ("RGBA"),
+    "linear", ycbcra709_to_rgba,
+    NULL
+  );
+  babl_conversion_new (
+    babl_model ("Y'CbCr709"),
+    babl_model ("RGBA"),
+    "linear", ycbcr709_to_rgba,
+    NULL
+  );
+}
+
+
+static void
+formats (void)
+{
+  babl_format_new (
+    babl_model ("Y'CbCrA709"),
+    babl_type ("float"),
+    babl_component ("Y'"),
+    babl_type ("float"),
+    babl_component ("Cb"),
+    babl_component ("Cr"),
+    babl_component ("alpha"),
+    NULL);
+
+  babl_format_new (
+    babl_model ("Y'CbCr709"),
+    babl_type ("float"),
+    babl_component ("Y'"),
+    babl_type ("float"),
+    babl_component ("Cb"),
+    babl_component ("Cr"),
+    NULL);
+}