Using GuestUser to show metadata only, and hide archives (images) to guests

I am in Omeka 2.1.4. I would like to use GuestUser to let 'guest' users access to metadata only, but not to archives (images). I understand this is possible by developing a plugin based on GuestUser plugin. Any advise please?

Is there a better solution to have some control on level of access to digital objects?. Many thanks.