simple translate “close” button?

Hy,
can you help me how to translate the “prettyPhoto” navigation Buttons?
Previous, Next and Close?

I’ve tried by myself with the plugin locoTranslate but i don’t find the “strings” and i’ve tried with some codesnippets, but it doesn’t work.
Something like this:

add_filter('gettext', 'translate_my_text' );
function translate_my_text($translated) {
	$translated = str_ireplace('Previous', 'Vorheriges', $translated);
	$translated = str_ireplace('Close', 'Schlie?en', $translated);
        $translated = str_ireplace('Next', 'Nächstes', $translated);
    return $translated; 
}

Regards ??