i just want to say that i habe found the part i was looking for where i can set the Attribute which is used for the lightbix title (line 135 in the lightbox.js):
function addToAlbum($link) {
self.album.push({
link: $link.attr('href'),
title: $link.attr('data-title') || $link.attr('title')
});
}
so everything is solved.