Can you put limits on scaling?

I was wondering if anyone knew of a way to allow scaling put to cap it off at a certain amount (such as 2x or something similar)? For example, if I made a game at 480x320 and allowed scaling, I might not want it to go above 960 x 640, because the quality of the graphics quickly deteriorates. Any ideas?

I had a similar issue with my game since I allow it to scale to any size but obviously that can get silly with huge or tiny sprites, so I just use something like Scale Min(0.5,WindowWidth/Something) etc to limit it to whatever looks right.