make it clear that noalpha doesn't compose

diff --git a/lib/Imager/Transformations.pod b/lib/Imager/Transformations.pod
index 33f6a30188ff4ca670cefc0ed4bfc457d8375e58..864ac0549de5d78e6c0eb9bf1113219b6b0b2aab 100644 (file)
--- a/lib/Imager/Transformations.pod
+++ b/lib/Imager/Transformations.pod
@@ -782,7 +782,8 @@ This weights the RGB channels at 22.2%, 70.7% and 7.1% respectively.
 =item *
 
 C<noalpha> - removes the alpha channel from a 2 or 4 channel image.
-An identity for other images.
+An identity for other images.  Warning: this removes the alpha channel
+without applying it.
 
 =item *