Index: imagefield_crop.module
===================================================================
--- imagefield_crop.module	(revision 770)
+++ imagefield_crop.module	(working copy)
@@ -112,6 +112,20 @@
   );
 }
 
+/**
+ * Implementation of hook_file_download().
+ */
+function imagefield_crop_file_download($filepath) {
+  $str = '.crop_display.jpg';
+  $len = drupal_strlen($str);
+  if (substr($filepath, - $len) == $str) {
+    $original_path = substr($filepath, 0, - $len);
+
+    /// @todo This may be not correct cause this may collect the same headers twice.
+    return module_invoke_all('file_download', $original_path);
+  }
+}
+
 function theme_imagefield_crop_widget_preview($item = NULL) {
   if (is_null($item) || empty($item['filepath'])) {
     return '<!-- link to default admin thumb -->';