media_gallery.theme.inc: how to get the filepath to the image-file of the detailpage?

How can I get the complete filepath and imagename.suffix to the image-file shown on the detailpage to set it in "$link_vars['link_path'] = 'something';"?

/**
* Displays a media item (entity) as a thumbnail on a Gallery collection page
*/
function theme_media_gallery_collection_thumbnail($variables) {
$element = $variables['element'];

// Get the rendered file without annoying DIV wrappers.
$element['file']['#theme'] = 'media_gallery_file_field_inline';
$image = drupal_render($element['file']);

$link_vars = array();
$link_vars['image'] = $image;
$link_vars['link_path'] = 'something';