static BWImage iBWIntegralImageToBWImage(BWIntegralImage img) {
  int w = img.w, h = img.h;
  BWImage out = new(w, h);
  for y to h:
    for x to w: {
      int pixel = iround(bwIntegralImage_getPixelAverage(img, x, y, x+1, y+1));
      out.setByte(x, y, (byte) pixel);
    }
  ret out;
}