static S imageToUtf(BWImage img) {
  int w = img.getWidth(), h = img.getHeight();
  if (h < 12) null;
  
  byte[] data = new byte[w-2];
  for (int x = 1; x < w-1; x++) {
    int b = 0;
    if (img.getPixel(x, 0) != 0
      || img.getPixel(x, 11) != 0)
      fail("not an utf8 image");
      
    for (int y = 2; y < 2+8; y++)
      b = b << 1 | (img.getPixel(x, y) > .5f ? 0 : 1);
      
    data[x-1] = (byte) b;
  }
  ret fromUtf8(data);
}

Began life as a copy of #1004602