The default quality setting for JPG is unusably low (25, if I remember it right). That still catches me out sometimes, late at night when I should really be in bed but I'll just try one more render... :) I usually save to PNG, which has the advantage of a transparent background. When I do switch to JPG I have to remember to jack the quality setting up too. Why it can't be a global preference setting like every image editor I've ever used, I don't know. - Edit - Sorry, I avoided answering your question in favour of a rant. :) If I'm going to postwork, I usually save at twice the intended final image size. To be fair, I don't do painted hair so the requirements for that could well be more demanding.