[babl] babl: make model_is_symmetric test adapt tolerance for high values

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

commit e8b753ff9dadfb4819e4f3876aa792e4a719cbfc
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Jul 4 12:32:07 2019 +0200

    babl: make model_is_symmetric test adapt tolerance for high values
    
    When the values used are in the billions, the tolerance that originally
    was mostly intended for values in the range 0.0-1.0 and its neighborhood
    break apart - use 1% of component values as symmetry threshold for such
    values.

 babl/babl-model.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/babl/babl-model.c b/babl/babl-model.c
index 90b1ad0..142734c 100644
--- a/babl/babl-model.c
+++ b/babl/babl-model.c
@@ -374,12 +374,17 @@ babl_model_is_symmetric (const Babl *cbabl)
       {
         int j;
         for (j = 0; j < 4; j++)
-          if (fabs (clipped[i *4 + j] - transformed[i * 4 + j]) > TOLERANCE)
+        {
+          float tolerance = TOLERANCE;
+          if (fabs(clipped[i*4+j]) > 1.0)
+            tolerance = fabs(clipped[i*4+j]) * 0.01;
+          if (fabs (clipped[i *4 + j] - transformed[i * 4 + j]) > tolerance)
             {
               if (!log)
                 log = 1;
               symmetric = 0;
             }
+        }
         if (log && log < 5)
           {
             babl_log ("%s", babl->instance.name);