RIPPED OFF by Preview, which overexposed all my tiffs while re-saving them

Running Preview on 10.6.8, relatively new to Macs and was trying to scan b&w tiffs into a single pdf. Made the mistake of hitting "save all" and BLAM! All my tiffs were re-saved as overexposed. Wasn't even given the option not to oversave existing files.

Sounds like the same problem as this question, left unanswered so far:

https://discussions.apple.com/thread/5655475?tstart=0#24091878?tstart=0

I have toyed with the limited Color and Profile tools in Preview to no avail. Can't even open the tiffs to try to repair them in Photoshop.

ANYONE KNOW OF A SOLUTION???? I will be RIPPED if I just lost all that content without having done anything wrong!

cheers, jodief1