Index: wp-includes/media.php
===================================================================
--- wp-includes/media.php	(revision 27901)
+++ wp-includes/media.php	(working copy)
@@ -578,6 +578,13 @@
 	if ( isset( $_wp_additional_image_sizes ) && count( $_wp_additional_image_sizes ) )
 		$image_sizes = array_merge( $image_sizes, array_keys( $_wp_additional_image_sizes ) );
 
+	/**
+	 * Filter the available image sizes
+	 *
+	 * @since 3.0.0
+	 *
+	 * @return array Returns a filtered array of image size strings
+	 */
 	return apply_filters( 'intermediate_image_sizes', $image_sizes );
 }
 
@@ -602,6 +609,12 @@
 	$src = false;
 
 	if ( $icon && $src = wp_mime_type_icon($attachment_id) ) {
+
+		/**
+		 * Filter the icon directory
+		 *
+		 * @since 2.5.0
+		 */
 		$icon_dir = apply_filters( 'icon_dir', ABSPATH . WPINC . '/images/media' );
 		$src_file = $icon_dir . '/' . wp_basename($src);
 		@list($width, $height) = getimagesize($src_file);