Hi Leona
Googlebot-image and any of the other bots that Google uses follow the rules set out for Googlebot so blocking Googlebot would block your images as it overrides Googlebot-image. I don't think that there is a way around this using the disallow directive as you are blocking the directory which contains your images so they won't be indexed using specific images.
Something you may want to consider is the Allow directive -
Disallow: /community/photos/
Allow: /community/photos/~username~/
that is if Google is already indexing images under the username path?
The allow directive will only be successful if it contains more or equal number of characters as the disallow path, so bare in mind that if you had the following;
Disallow: /community/photos/
Allow: /community/photos/
the allow will win out and nothing will be blocked. please note that i haven't actioned the allow directive myself but looked into it in depth when i studied the robots.txt for my own sites it would be good if someone else had an experience of this directive. Hope this helps.