static L<BWImage> unclusterImages(BWImage img) {

  int w = img.getWidth(), h = img.getHeight();

  L<Int> bc = unclusterImages_findBlackCols(img);

  L<Int> br = unclusterImages_findBlackRows(img);

  if (!bc.contains(0) || !br.contains(0)

    || !bc.contains(w-1) || !br.contains(h-1))

    null;

  new L<BWImage> images;

  for (int y = 1; y < l(br)-1; y++)

    for (int x = 1; x < l(bc)-1; x++) {

      int x1 = bc.get(x)+1, cw = bc.get(x+1)-x1;

      int y1 = br.get(y)+1, ch = br.get(y+1)-y1;

      images.add(img.clip(x1, y1, cw, ch));

    }

  ret images;

}

static L<Int> unclusterImages_findBlackCols(BWImage img) {

  new L<Int> l;

  int w = img.getWidth(), h = img.getHeight();

  outer: for (int x = 0; x < w; x++) {

    for (int y = 0; y < h; y++)

      if (img.getPixel(x, y) > 0.1f)

        continue outer;

    l.add(x);

  }

  ret l;

}

static L<Int> unclusterImages_findBlackRows(BWImage img) {

  new L<Int> l;

  int w = img.getWidth(), h = img.getHeight();

  outer: for (int y = 0; y < h; y++) {

    for (int x = 0; x < w; x++)

      if (img.getPixel(x, y) > 0.1f)

        continue outer;

    l.add(y);

  }

  ret l;

}