babl r356 - in trunk: . babl babl/base extensions

[martinn svn gnome org]

Author: martinn
Date: Sun Nov 16 12:36:50 2008
New Revision: 356
URL: http://svn.gnome.org/viewvc/babl?rev=356&view=rev

Log:
* babl/babl.h: Add #define BABL_ALPHA_THRESHOLD which is the alpha
threshold used in the reference implementation for
un-pre-multiplication of color data.

* babl/base/model-rgb.c
* babl/base/model-gray.c
* extensions/gegl-fixups.c: Use the define, a consistent alpha
threshold improves accurucy of conversions.


Modified:
   trunk/ChangeLog
   trunk/babl/babl.h
   trunk/babl/base/model-gray.c
   trunk/babl/base/model-rgb.c
   trunk/extensions/gegl-fixups.c

Modified: trunk/babl/babl.h
==============================================================================
--- trunk/babl/babl.h	(original)
+++ trunk/babl/babl.h	Sun Nov 16 12:36:50 2008
@@ -45,6 +45,11 @@
  */
 #define BABL_MAGIC   0xbAb100
 
+/* Alpha threshold used in the reference implementation for
+ * un-pre-multiplication of color data.
+ */
+#define BABL_ALPHA_THRESHOLD 0.0001
+
 enum {
   BABL_INSTANCE = BABL_MAGIC,
   BABL_TYPE,

Modified: trunk/babl/base/model-gray.c
==============================================================================
--- trunk/babl/base/model-gray.c	(original)
+++ trunk/babl/base/model-gray.c	Sun Nov 16 12:36:50 2008
@@ -308,7 +308,7 @@
       double luminance = *(double *) src[0];
       double alpha     = *(double *) src[1];
 
-      if (alpha > 0.00001)
+      if (alpha > BABL_ALPHA_THRESHOLD)
         {
           luminance = luminance / alpha;
         }
@@ -408,7 +408,7 @@
       alpha = *(double *) src[src_bands - 1];
       for (band = 0; band < src_bands - 1; band++)
         {
-          if (alpha > 0.001)
+          if (alpha > BABL_ALPHA_THRESHOLD)
             {
               *(double *) dst[band] = *(double *) src[band] / alpha;
             }

Modified: trunk/babl/base/model-rgb.c
==============================================================================
--- trunk/babl/base/model-rgb.c	(original)
+++ trunk/babl/base/model-rgb.c	Sun Nov 16 12:36:50 2008
@@ -283,7 +283,7 @@
       alpha = *(double *) src[src_bands - 1];
       for (band = 0; band < src_bands - 1; band++)
         {
-          if (alpha > 0.001)
+          if (alpha > BABL_ALPHA_THRESHOLD)
             {
               *(double *) dst[band] = *(double *) src[band] / alpha;
             }
@@ -332,7 +332,7 @@
   while (n--)
     {
       double alpha = ((double *) src)[3];
-      if (alpha > 0.0001)
+      if (alpha > BABL_ALPHA_THRESHOLD)
         {
           ((double *) dst)[0] = gamma_2_2_to_linear (((double *) src)[0] / alpha);
           ((double *) dst)[1] = gamma_2_2_to_linear (((double *) src)[1] / alpha);

Modified: trunk/extensions/gegl-fixups.c
==============================================================================
--- trunk/extensions/gegl-fixups.c	(original)
+++ trunk/extensions/gegl-fixups.c	Sun Nov 16 12:36:50 2008
@@ -337,7 +337,7 @@
         {
           float ca = src[i];
           int   ret;
-          if (alpha < 0.0001)
+          if (alpha < BABL_ALPHA_THRESHOLD)
             ret = 0;
           else
             ret = table_F_8g[gggl_float_to_index16 (ca / alpha)];
@@ -393,7 +393,7 @@
   while (n--)
     {
       float alpha = src[3];
-      if (alpha < 0.00001)
+      if (alpha < BABL_ALPHA_THRESHOLD)
         {
           dst[0] = 0;
           dst[1] = 0;
@@ -471,7 +471,7 @@
     {
       float alpha = src[3];
       float recip = 1.0/alpha;
-      if (alpha < 0.00001)
+      if (alpha < BABL_ALPHA_THRESHOLD)
         recip = 0.0;
       dst[0] = src[0] * recip;
       dst[1] = src[1] * recip;
@@ -498,7 +498,7 @@
     {
       float alpha = src[3];
       float recip = (1.0/alpha);
-      if (alpha < 0.00001)
+      if (alpha < BABL_ALPHA_THRESHOLD)
         {
           dst[0] = dst[1] = dst[2] = dst[3] = 0;
         }