Is there a way to filter out just the photos that have not been tagged at all? We have amassed a large quantity of photos with different people tagging, and now need a comprehensive view of what photos still require tagging.
No, sorry, there is no facility. You could write something using the object model or the direct "dirty" way via the database. See the admin overview database overview and the pdf in the /docs folder of your install for the general relations.
