since you mentioned Irfanview, whether you have tried it, and if so, did it work as you wanted?
In th past I used Alchemy's Graphic Workshop for batch conversions, but I understand they no longer have a free version.
I have tiff image files with 48 bit color depth (scans), which I'd like to convert to jpeg (normal color depth). Since I have a whole lot of them, I'd need a program that can do a batch conversion (maybe like IrfanView).
Does anybody know a good, free converter for those files?