static BufferedImage cutOutRegionFromImage(IImageRegion region) {
  if (region == null) null;
  var fullImage = toBufferedImage(region.image());
  var r = region.bounds();
  var clipped = clipBufferedImage(fullImage, r);
  int[] pixels = pixelsOfBufferedImage(clipped);
  int w = r.w, h = r.h, i = 0;
  for y to h:
    for x to w: {
      if (!region.contains(r.x+x, r.y+y))
        pixels[i] = 0;
      ++i;
    }
  ret bufferedImageWithAlpha(w, h, pixels);
}