But it's not just images that are copyrighted. Anything written is copyrighted as well, as well as any created work. By law it is copyrighted the moment it is created, whether it is registered with the Copyright office or not. I really don't see how the owners of archive.org have a leg to stand on.
The problem is if you can get an attorney to take the case. I have run into this before. Then started copyrighting things at the copyright office.