Hi,
as far as I can see, it is not possible to achieve this level of privacy. You may try the
privacy plugin
that allows to tune some settings. But it is impossible to keep people
(even if they are not registered) from getting access to all the photos on your site. The problem is that the photo plugin stores all images in the same
folder incrementing the number. With this knowledge everybody can fetch
all the photos stored on your site. Have a look:
yoursite.com/ow_userfiles/plugins/photo/photo_1.jpg
and maybe (depends on the number of photos on your site)
yoursite.com/ow_userfiles/plugins/photo/photo_81.jpg
Someone over here is addressing the same problem:
Adding more privacy to the plugin photo
To fix this problem, the filehandling of the photo plugin has to be rewritten, which is far beyond my programming skills. I am currently working out a quick fix, that prevents the whole world from viewing the photos only giving access to registered users. If you are interested in my solution, drop me a note.
best regards,
Oliver