static BWImage scaledBWImageFromBWIntegralImage(int w, IBWIntegralImage img) {
  ret scaledBWImageFromBWIntegralImage(img, w);
}

static BWImage scaledBWImageFromBWIntegralImage(IBWIntegralImage img, int w, int h default heightForWidth(img, w)) {
  byte[] pixels = img cast BWIntegralImage
    ? scaledGrayBytesFromBWIntegralImage(img, w, h)
    : scaledGrayBytesFromBWIntegralImage(img, w, h);
  ret new BWImage(w, h, pixels);
}