taking a small dpi pic(400 dpi)up to a larger size(800 dpi) usually will cause sharpness to deteriorate. taking a large dpi(3270 x 2304 dpi) and decreasing to a (800 dpi) will increase the shapness. and make for a really good print.
digital cameras today can take pics in the 10-20 MEGA PIXEL range, capture hugh photos. my fiji S700 is a 10 mega pixel, and when i open the photo in photo editiing it is 3270 x 2240 or some where near that size. this translates to INCHES of 42 inches X 32 inches!!!!! if you print at that size, it will be nice and clean.