Index: modules/image/image.field.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/image/image.field.inc,v
retrieving revision 1.21
diff -u -p -r1.21 image.field.inc
--- modules/image/image.field.inc	30 Apr 2010 12:53:47 -0000	1.21
+++ modules/image/image.field.inc	4 Jun 2010 20:49:03 -0000
@@ -465,7 +465,7 @@ function image_field_formatter_view($ent
 
   // Check if the formatter involves a particular image style.
   $matches = array();
-  if (preg_match('/__([a-z0-9_]+)/', $display['type'], $matches)) {
+  if (preg_match('/__([a-z0-9_-]+)/', $display['type'], $matches)) {
     $image_style = $matches[1];
   }