static BufferedImage pointsToImage(Iterable<Pt> points) {
  var pointsList = asList(points);
  if (empty(pointsList)) ret whiteImage(1);
  Pt size = maxPt(pointsList);
  var img = whiteImage(size.x, size.y);
  for (p : pointsList)
    setPixel(img, p, Color.black);
  ret img;
}