Could this suits your needs : http://ez.no/community/contribs/applications/ezlightbox ?
However, you can access an image url like this. Provided you have an image datatype.
$attribute.content.IMAGE_VARIATION.full_path
Where :
$attribute is your image attribute. So you'll probably need to replace $attribute by something like <b>$node.data_map.image</b> IMAGE_VARIATION = an image size defined in your image.ini settings or "original" which is the unresized format of your image.
