Thickbox Lightbox größe der geladenen Bilder

<?php # -*- coding: utf-8 -*-
/**
 * Plugin Name: T5 Add Thickbox Support
 * Plugin URI:  http://toscho.de/?p=1997
 * Description: Enables the Thickbox script for the theme.
 * Version:     2012.08.12
 * Author:      Thomas Scholz <info@toscho.de>
 * Author URI:  http://toscho.de
 * License:     MIT
 * License URI: http://www.opensource.org/licenses/mit-license.php
*/
add_action( 'wp_enqueue_scripts', 'add_thickbox' );
add_action( 'wp_footer', 't5_thickbox_jquery' );
/**
 * Print JavaScript to make linked images thickboxy.
 *
 * @return void
 */
function t5_thickbox_jquery()
{
?>
<script>
jQuery( 'a img.size-medium, a img.attachment-thumbnail' )
    .parent()
    .addClass( 'thickbox' )
    .attr( 'rel', 'page' );
</script>
<?php
}