OpenPhoto doesn't have the concept of "users". Any user can sign in (at the moment) with BrowserID which basically says that the user viewing owns a given email address. This allows anyone to sign in to any OpenPhoto site - without having an "OpenPhoto" account.
From there all permissions are based on email address. I can give any user access to any photo by their email address.
Not sure what you mean by giving Flickr permission to look at a photo. If you give an app permission to your photos that's done via OAuth and you can revoke that token at any time.
OpenPhoto doesn't have the concept of "users". Any user can sign in (at the moment) with BrowserID which basically says that the user viewing owns a given email address. This allows anyone to sign in to any OpenPhoto site - without having an "OpenPhoto" account.
From there all permissions are based on email address. I can give any user access to any photo by their email address.
Not sure what you mean by giving Flickr permission to look at a photo. If you give an app permission to your photos that's done via OAuth and you can revoke that token at any time.