--- image.module (saved version)
+++ (current document)
@@ -84,7 +84,7 @@
     'access callback' => TRUE,
     'type' => MENU_CALLBACK,
   );
-  // Generate and deliver image derivatives of private files.
+  // Generate and deliver image derivatives files that are not delivered through public://.
   // These image derivatives are always delivered through the menu system.
   $items['system/files/styles/%image_style'] = array(
     'title' => 'Generate image style',
@@ -659,9 +659,9 @@
   $image_uri = $scheme . '://' . $target;
   $derivative_uri = image_style_path($style['name'], $image_uri);
 
-  // If using the private scheme, let other modules provide headers and
+  // If not using the public scheme, let other modules provide headers and
   // control access to the file.
-  if ($scheme == 'private') {
+  if ($scheme != 'public') {
     if (file_exists($derivative_uri)) {
       file_download($scheme, file_uri_target($derivative_uri));
     }
@@ -800,7 +800,7 @@
  */
 function image_style_url($style_name, $path) {
   $scheme = file_uri_scheme($path);
-  if ($scheme === 'private') {
+  if ($scheme !== 'public') {
     $target = file_uri_target($path);
     $url = url('system/files/styles/' . $style_name . '/' . $scheme . '/' . $target, array('absolute' => TRUE));
   }