[Olaf Lederer]

By default mage tags are not allowed too.

create you own plugin and use this code

function allow_img_tag($tags) {

$tags['img'] = array('src' => array(), 'title' => array(), 'alt' => array());

return $tags;

}

add_filter('bb_allowed_tags', 'allow_img_tag');

You can the same kind of function for your header elements