[gegl] channel-mixer: operate on linear RGB, remove clipping

[Øyvind Kolås <ok src gnome org>]

commit d2c672dc169016085972ce87c9a2ce018811aad8
Author: Elle Stone <ellestone ninedegreesbelow com>
Date:   Mon Oct 19 09:51:42 2015 -0400

    channel-mixer: operate on linear RGB, remove clipping
    
    To avoid hue/luminance shifts, and get radiometrically correct results.

 operations/common/channel-mixer.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/operations/common/channel-mixer.c b/operations/common/channel-mixer.c
index 272680f..27dc660 100644
--- a/operations/common/channel-mixer.c
+++ b/operations/common/channel-mixer.c
@@ -130,12 +130,12 @@ static void prepare (GeglOperation *operation)
   if (input_format == NULL || babl_format_has_alpha (input_format))
     {
       mix->has_alpha = TRUE;
-      format = babl_format ("R'G'B'A float");
+      format = babl_format ("RGBA float");
     }
   else
     {
       mix->has_alpha = FALSE;
-      format = babl_format ("R'G'B' float");
+      format = babl_format ("RGB float");
     }
 
   gegl_operation_set_format (operation, "input", format);
@@ -179,7 +179,7 @@ cm_mix_pixel (CmChannelType *ch,
 
   c *= norm;
 
-  return (gfloat) MIN(1, MAX(0, c));
+  return (gfloat) c;
 }
 
 static inline void