How to repair corrupt photo library

I've been having corrupt photo library messages for the past few months, causing spontaneous shutdown or iphoto, and I was hoping the conversion to photo would somehow magically repair the problem. Well, it didn't.

All my photos are there and I can start browsing but then a corrupt library message comes up and closes the program. Sometimes the library won't even open with the same message.

How do I repair the library without losing any pics?