Hmm. Reducing the size does not trigger the resize thing. It may have been an addon. AndyB has one, but we need a different image processor that would mean we'd have to have the host add something. I'll keep looking.
I think it was a function of everything being uploaded, before the accidental wipe. Now that we're back to hotlinking, it doesn't manipulate the image at all. The images I've sent as attachments to my posts that were 1080p got resized down same as before.