Just remember this rule of thumb and add to it, it takes 2 pixels to define a line.
Quote:It is generally accepted that a normal human eye can distinguish 5 lines per millimeter at a distance of 25 cm.
In other words, a 3MP image (2048x1536pixels) would be best printed in a photolab on a standard 13x17cm photopaper and it would be as sharp as your eys can take it.
