Yes, 0.1mm would be much better, that's 254 DPI. You'd also want 24 bits (3 bytes) per pixel instead of 1 bit. That gives you 0.43x0.43 miles, which is still mighty impressive.
72 DPI hasn't been current since well before retina displays, you might have to go all the way back to the original Macintosh. Even an old 14" 1024x768 display was 91 DPI.
