svoid verifyImage2B(BWImage img, Image2B binaryImage, int threshold) {
  assertSameSize(img, binaryImage);
  int w = img.w(), h = img.h();
  
  for y to h:
    for x to w:
      if ((img.getInt(x, y) >= threshold) != binaryImage.getBoolPixel(x, y))
        fail("Wrong pixel at " + x + "/" + y);
}