static L<RectAndMD5> segmentScreenToCacheFile() {
  new L<RectAndMD5> out;
  for (Rect r : autoSegment(shootScreenBW()))
    out.add(RectAndMD5(r, rgbMD5(bwScreenShot.clip(r).toRGB())));
  saveTextFile(segmentedScreenCacheFile(), struct(out));
  ret out;
}