[gegl] operations: add gegl:color-enhance

[Thomas Manni <tmanni src gnome org>]

commit 19f8868b50e336f0a3b8a05ee8c994f0a4eff18b
Author: Thomas Manni <thomas manni free fr>
Date:   Tue Jan 13 20:00:00 2015 +0100

    operations: add gegl:color-enhance

 operations/common/Makefile.am                  |    1 +
 operations/common/color-enhance.c              |  242 ++++++++++++++++++++++++
 po/POTFILES.in                                 |    1 +
 tests/compositions/Makefile.am                 |    1 +
 tests/compositions/color-enhance.xml           |   11 +
 tests/compositions/reference/color-enhance.png |  Bin 0 -> 140850 bytes
 6 files changed, 256 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/Makefile.am b/operations/common/Makefile.am
index 76839cb..2833161 100644
--- a/operations/common/Makefile.am
+++ b/operations/common/Makefile.am
@@ -24,6 +24,7 @@ op_LTLIBRARIES = \
        cartoon.la \
        channel-mixer.la \
        checkerboard.la \
+       color-enhance.la \
        color-exchange.la \
        color-reduction.la \
        color-rotate.la \
diff --git a/operations/common/color-enhance.c b/operations/common/color-enhance.c
new file mode 100644
index 0000000..ecd160f
--- /dev/null
+++ b/operations/common/color-enhance.c
@@ -0,0 +1,242 @@
+/* This file is an image processing operation for GEGL
+ *
+ * GEGL 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.
+ *
+ * GEGL 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 GEGL; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * This operation is inspired from the color enhance gimp plugin.
+ * It alters the chroma component to cover maximum possible range,
+ * keeping hue and lightness untouched.
+ *
+ * Thomas Manni <thomas manni free fr>
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+#include <math.h>
+
+#ifdef GEGL_PROPERTIES
+
+#else
+
+#define GEGL_OP_FILTER
+#define GEGL_OP_C_FILE  "color-enhance.c"
+
+#include "gegl-op.h"
+
+static void
+buffer_get_min_max (GeglBuffer *buffer,
+                    gdouble    *min,
+                    gdouble    *max)
+{
+  GeglBufferIterator *gi;
+
+  gi = gegl_buffer_iterator_new (buffer, NULL, 0, babl_format ("CIE LCH(ab) float"),
+                                 GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+
+  *min = G_MAXDOUBLE;
+  *max = -G_MAXDOUBLE;
+
+  while (gegl_buffer_iterator_next (gi))
+    {
+      gint o;
+      gfloat *buf = gi->data[0];
+
+      for (o = 0; o < gi->length; o++)
+        {
+          *min = MIN (buf[1], *min);
+          *max = MAX (buf[1], *max);
+          buf += 3;
+        }
+    }
+}
+
+static void prepare (GeglOperation *operation)
+{
+  const Babl *format;
+  const Babl *in_format = gegl_operation_get_source_format (operation, "input");
+
+  if (in_format)
+    {
+       if (babl_format_has_alpha (in_format))
+         format = babl_format ("CIE LCH(ab) alpha float");
+       else
+         format = babl_format ("CIE LCH(ab) float");
+    }
+  else
+    {
+      format = babl_format ("CIE LCH(ab) float");
+    }
+
+  gegl_operation_set_format (operation, "input", format);
+  gegl_operation_set_format (operation, "output", format);
+}
+
+static GeglRectangle
+get_required_for_output (GeglOperation       *operation,
+                         const gchar         *input_pad,
+                         const GeglRectangle *roi)
+{
+  GeglRectangle result = *gegl_operation_source_get_bounding_box (operation, "input");
+
+  /* Don't request an infinite plane */
+  if (gegl_rectangle_is_infinite_plane (&result))
+    return *roi;
+
+  return result;
+}
+
+static GeglRectangle
+get_cached_region (GeglOperation       *operation,
+                   const GeglRectangle *roi)
+{
+  GeglRectangle result = *gegl_operation_source_get_bounding_box (operation, "input");
+
+  if (gegl_rectangle_is_infinite_plane (&result))
+    return *roi;
+
+  return result;
+}
+
+
+static gboolean
+process (GeglOperation       *operation,
+         GeglBuffer          *input,
+         GeglBuffer          *output,
+         const GeglRectangle *result,
+         gint                 level)
+{
+  const Babl *format = gegl_operation_get_format (operation, "output");
+  gboolean has_alpha = babl_format_has_alpha (format);
+  GeglBufferIterator *gi;
+  gdouble  min;
+  gdouble  max;
+  gdouble  delta;
+
+  buffer_get_min_max (input, &min, &max);
+
+  gi = gegl_buffer_iterator_new (input, result, 0, format,
+                                 GEGL_ACCESS_READ, GEGL_ABYSS_NONE);
+
+  gegl_buffer_iterator_add (gi, output, result, 0, format,
+                            GEGL_ACCESS_WRITE, GEGL_ABYSS_NONE);
+
+  delta = max - min;
+
+  if (! delta)
+    {
+      gegl_buffer_copy (input, NULL, output, NULL);
+      return TRUE;
+    }
+
+  if (has_alpha)
+    {
+      while (gegl_buffer_iterator_next (gi))
+        {
+          gfloat *in  = gi->data[0];
+          gfloat *out = gi->data[1];
+
+          gint i;
+          for (i = 0; i < gi->length; i++)
+            {
+              out[0] = in[0];
+              out[1] = (in[1] - min) / delta * 100.0;
+              out[2] = in[2];
+              out[3] = in[3];
+
+              in  += 4;
+              out += 4;
+            }
+        }
+    }
+  else
+    {
+       while (gegl_buffer_iterator_next (gi))
+        {
+          gfloat *in  = gi->data[0];
+          gfloat *out = gi->data[1];
+
+          gint i;
+          for (i = 0; i < gi->length; i++)
+            {
+              out[0] = in[0];
+              out[1] = (in[1] - min) / delta * 100.0;
+              out[2] = in[2];
+
+              in  += 3;
+              out += 3;
+            }
+        }
+    }
+
+  return TRUE;
+}
+
+/* Pass-through when trying to perform a reduction on an infinite plane
+ */
+static gboolean
+operation_process (GeglOperation        *operation,
+                   GeglOperationContext *context,
+                   const gchar          *output_prop,
+                   const GeglRectangle  *result,
+                   gint                  level)
+{
+  GeglOperationClass  *operation_class;
+
+  const GeglRectangle *in_rect =
+    gegl_operation_source_get_bounding_box (operation, "input");
+
+  operation_class = GEGL_OPERATION_CLASS (gegl_op_parent_class);
+
+  if (in_rect && gegl_rectangle_is_infinite_plane (in_rect))
+    {
+      gpointer in = gegl_operation_context_get_object (context, "input");
+      gegl_operation_context_take_object (context, "output",
+                                          g_object_ref (G_OBJECT (in)));
+      return TRUE;
+    }
+
+  /* chain up, which will create the needed buffers for our actual
+   * process function
+   */
+  return operation_class->process (operation, context, output_prop, result,
+                                   gegl_operation_context_get_level (context));
+}
+
+static void
+gegl_op_class_init (GeglOpClass *klass)
+{
+  GeglOperationClass       *operation_class;
+  GeglOperationFilterClass *filter_class;
+
+  operation_class = GEGL_OPERATION_CLASS (klass);
+  filter_class    = GEGL_OPERATION_FILTER_CLASS (klass);
+
+  filter_class->process = process;
+
+  operation_class->prepare = prepare;
+  operation_class->process = operation_process;
+  operation_class->get_required_for_output = get_required_for_output;
+  operation_class->get_cached_region = get_cached_region;
+  operation_class->opencl_support = FALSE;
+
+  gegl_operation_class_set_keys (operation_class,
+    "name",        "gegl:color-enhance",
+    "title",       _("Color Enhance"),
+    "categories" , "color:enhance",
+    "description",
+        _("Stretch color chroma to cover maximum possible range, "
+          "keeping hue and lightness untouched."),
+        NULL);
+}
+
+#endif
diff --git a/po/POTFILES.in b/po/POTFILES.in
index bd011f6..3aa29ae 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -19,6 +19,7 @@ operations/common/cartoon.c
 operations/common/channel-mixer.c
 operations/common/checkerboard.c
 operations/common/color.c
+operations/common/color-enhance.c
 operations/common/color-exchange.c
 operations/common/color-reduction.c
 operations/common/color-rotate.c
diff --git a/tests/compositions/Makefile.am b/tests/compositions/Makefile.am
index cb21a1f..d7d65b9 100644
--- a/tests/compositions/Makefile.am
+++ b/tests/compositions/Makefile.am
@@ -21,6 +21,7 @@ TESTS = \
   checkerboard.xml                \
   clones.xml                      \
   colors.xml                      \
+  color-enhance.xml               \
   color-exchange.xml              \
   color-to-alpha.xml              \
   composite-transform.xml         \
diff --git a/tests/compositions/color-enhance.xml b/tests/compositions/color-enhance.xml
new file mode 100644
index 0000000..76e79c7
--- /dev/null
+++ b/tests/compositions/color-enhance.xml
@@ -0,0 +1,11 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<gegl>
+  <node operation='gegl:color-enhance'>
+  </node>
+  <node operation='gegl:load'>
+    <params>
+      <param name='path'>data/parliament_0.png</param>
+    </params>
+  </node>
+</gegl>
+
diff --git a/tests/compositions/reference/color-enhance.png b/tests/compositions/reference/color-enhance.png
new file mode 100644
index 0000000..df0bc51
Binary files /dev/null and b/tests/compositions/reference/color-enhance.png differ