Index: src/wp-includes/media.php
===================================================================
--- src/wp-includes/media.php	(revision 42186)
+++ src/wp-includes/media.php	(working copy)
@@ -271,8 +271,9 @@
  * @param string     $name   Image size identifier.
  * @param int        $width  Image width in pixels.
  * @param int        $height Image height in pixels.
- * @param bool|array $crop   Optional. Whether to crop images to specified width and height or resize.
- *                           An array can specify positioning of the crop area. Default false.
+ * @param bool|array $crop   Optional. If true, images will be crop without any adjustments
+ *                           in dimensions. Otherwise try to adjust images dimensions
+ *                           according specified width and height parameters before we crop it.
  */
 function add_image_size( $name, $width = 0, $height = 0, $crop = false ) {
 	global $_wp_additional_image_sizes;