Index: image.gd.inc
===================================================================
--- image.gd.inc	(revision 366)
+++ image.gd.inc	(working copy)
@@ -336,7 +336,7 @@
  */
 function image_gd_get_info(stdClass $image) {
   $details = FALSE;
-  $data = getimagesize($image->source);
+  $data = getimagesize(str_replace('public:/', DRUPAL_ROOT .'/'. file_directory_path(), $image->source));
 
   if (isset($data) && is_array($data)) {
     $extensions = array('1' => 'gif', '2' => 'jpg', '3' => 'png');