static BufferedImage pointsToImage(Iterable<Pt> points) {
  var pointsList = asList(points);
  if (empty(pointsList)) ret whiteImage(1);
  Rect bounds = boundsOfPts(pointsList);
  var img = whiteImage(bounds.w+2, bounds.h+2);
  for ping (p : pointsList)
    setPixel(img, p.x-bounds.x+1, p.y-bounds.y+1, Color.black);
  ret img;
}