static ItIt<Pt> pixelsInImageIterator(BufferedImage image) {
  ret pixelsInImageIterator(image.getWidth(), image.getHeight());
}

static ItIt<Pt> pixelsInImageIterator(WidthAndHeight etc size) {
  int h = size.h(), w = size.w();
  ret new ItIt<Pt> {
    int x, y;
    
    public bool hasNext() {
      ret y < h && x < w;
    }
    
    public Pt next() {
      Pt p = pt(x, y);
      if (++x >= w) { x = 0; ++y; }
      ret p;
    }
  };
}