// m = cols, n = rows
static L<BufferedImage> imageToTiles(BufferedImage img, int m, int n) {
  new L<BufferedImage> tiles;
  int w = img.getWidth(), h = img.getHeight();
  if (m > w || n > h)
    fail("Too many tiles (" + m + "/" + n + ") for image of size " + w + "*" + h);
    
  for y to n: {
    int y1 = y*h/n, y2 = (y+1)*h/n;
    for x to m: {
      int x1 = x*w/m, x2 = (x+1)*w/m;
      Rect r = /*rectMinSize(1, 1,*/ rectFromPoints(x1, y1, x2, y2)/*)*/;
      tiles.add(clipBufferedImage(img, r));
    }
  }
  ret tiles;
}