Exact thumbnails

[Bloom]

Hey, I have yet to upgrade my gallery, and I noticed the nifty option that let's your thumbnails be an exact width! The trouble is, I really want that, but my site has 2000+ in the gallery, other galleries a lot more. If I was to upgrade, and then change the settings, I believe it would change all thumbnails in the gallery, however old. But, is there a way to make that happen without the old thumbnails being stretched, and thus making them look blurry because they weren't exact dimensions previously? I've seen this on a few galleries, and was wondering if there was a way around it to keep the thumbnails looking good in exact width and height?

I'm upgrading in a few days, and any help would really be helpful! (:

[Stramm]

the admin tools have an option to recreate thumbs and intermediate images