sprites can be enlarged, but.. you must do that with a very high reso and have ps at bicubic sharper (in prefs). then when enlarged go to image size, cut down the reso, but!!! then keep the same amount of pixels vert and hor. or keep on working in the high reso to keep the hq and cut down in the end
that's how i keep my tags hq.
edit: did i say bicubic sharper when enlarging?? d*** i must be drunk!! sorry folks, bicubic sharper is when you make 'm smaller. bicubic smoother is when you enlarge... please forgive me for my mistake, i'll never drink again, lol, but that's a lie!!