[babl/wip/pippin/inverted-cmyk] CMYK: add back non-inverted CMYK model

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 4875717e3ae54acf1d30bd4f04ba190c35d1a909
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Nov 20 18:53:53 2018 +0100

    CMYK: add back non-inverted CMYK model

 extensions/CMYK.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 98 insertions(+), 2 deletions(-)
---
diff --git a/extensions/CMYK.c b/extensions/CMYK.c
index 40ed246..9abec66 100644
--- a/extensions/CMYK.c
+++ b/extensions/CMYK.c
@@ -129,6 +129,104 @@ cmyka_to_cmyk (const Babl *conversion,char *src,
     }
 }
 
+/////////////////////
+static void
+cmyka_to_CMYKA (const Babl *conversion,char *src,
+                char *dst,
+                long  n)
+{
+  while (n--)
+    {
+      double cyan    = ((double *) src)[0];
+      double magenta = ((double *) src)[1];
+      double yellow  = ((double *) src)[2];
+      double key     = ((double *) src)[3];
+      double alpha   = ((double *) src)[4];
+
+      ((double *) dst)[0] = (1.0-cyan)    * alpha;
+      ((double *) dst)[1] = (1.0-magenta) * alpha;
+      ((double *) dst)[2] = (1.0-yellow)  * alpha;
+      ((double *) dst)[3] = (1.0-key)     * alpha;
+      ((double *) dst)[4] = alpha;
+
+      src += 5 * sizeof (double);
+      dst += 5 * sizeof (double);
+    }
+}
+
+static void
+CMYKA_to_cmyka (const Babl *conversion,char *src,
+                char *dst,
+                long  n)
+{
+  while (n--)
+    {
+      double alpha   = ((double *) src)[4];
+      double ralpha  = alpha>0.000001?1.0/alpha:0.0;
+      double cyan   = ((double *) src)[0] * ralpha;
+      double magenta= ((double *) src)[1] * ralpha;
+      double yellow = ((double *) src)[2] * ralpha;
+      double key    = ((double *) src)[3] * ralpha;
+
+      ((double *) dst)[0] = 1.0-cyan;
+      ((double *) dst)[1] = 1.0-magenta;
+      ((double *) dst)[2] = 1.0-yellow;
+      ((double *) dst)[3] = 1.0-key;
+      ((double *) dst)[4] = alpha;
+
+      src += 5 * sizeof (double);
+      dst += 5 * sizeof (double);
+    }
+}
+
+
+
+static void
+CMYK_to_cmyka (const Babl *conversion,char *src,
+               char *dst,
+               long  n)
+{
+  while (n--)
+    {
+      double cyan    = ((double *) src)[0];
+      double magenta = ((double *) src)[1];
+      double yellow  = ((double *) src)[2];
+      double key     = ((double *) src)[3];
+
+      ((double *) dst)[0] = 1.0-cyan;
+      ((double *) dst)[1] = 1.0-magenta;
+      ((double *) dst)[2] = 1.0-yellow;
+      ((double *) dst)[3] = 1.0-key;
+      ((double *) dst)[4] = 1.0;
+
+      src += 4 * sizeof (double);
+      dst += 5 * sizeof (double);
+    }
+}
+
+static void
+cmyka_to_CMYK (const Babl *conversion,char *src,
+               char *dst,
+               long  n)
+{
+  while (n--)
+    {
+      double cyan    = ((double *) src)[0];
+      double magenta = ((double *) src)[1];
+      double yellow  = ((double *) src)[2];
+      double key     = ((double *) src)[3];
+
+      ((double *) dst)[0] = 1.0-cyan;
+      ((double *) dst)[1] = 1.0-magenta;
+      ((double *) dst)[2] = 1.0-yellow;
+      ((double *) dst)[3] = 1.0-key;
+
+      src += 5 * sizeof (double);
+      dst += 4 * sizeof (double);
+    }
+}
+
+
 
 
 
@@ -591,7 +689,6 @@ init (void)
     NULL
   );
 
-#if 0
   babl_conversion_new (
     babl_model ("cmykA"),
     babl_model ("CMYK"),
@@ -616,7 +713,6 @@ init (void)
     "linear", CMYKA_to_cmyka,
     NULL
   );
-#endif