Super2XSaI is a combination of techniques for blending and interpolating sprites to enlarge the finished product in a way that doesn't look too bad. It's great for a sprite based game. But if you are talking about a single flat image, then Shock is right, there is no way to improve the pixels that are there. You can enlarge them and then blur the result so that you don't see the resulting gigantic pixels but that doesn't add quality it just reduces the visible drop in quality from enlarging it.