I maintain all of my photos on a separate hard drive on my network. I've imported them into iPhoto but did not select "copy to iPhoto", so they're merely referenced from the network drive. I've gone through and made some edits, tagged faces, etc., and now I'd like to back up my iPhoto library. However, I've noticed that the library is over 20GB. Most of this, it would seem, consists of previews and thumbnails.
Is there an easy way to back up my iPhoto library WITHOUT these images? I'm mostly concerned about the other data — faces, etc. — that are defined within iPhoto, since the photos themselves are backed up separately. Thoughts?