static FoundImg rgbImageSearch_best(RGBImage big, RGBImage pat, float similarity) {
  new Best<Rect> best;
  int wp = pat.getWidth(), hp = pat.getHeight();
  int w = big.getWidth(), h = big.getHeight();
  float maxError = (1f-similarity)*wp*hp;
  bigloop: for (int y = 0; y < h-hp; y++)
    for (int x = 0; x < w-wp; x++) {
      float diff = rgbImageSectionsSimilarity(big, pat, x, y, maxError);
      if (diff <= maxError && best.isNewBest(-diff)) {
        maxError = diff;
        Rect r = new Rect(x, y, wp, hp);
        best.put(r, -diff);
        ping();
        if (diff == 0) break bigloop;
      }
    }
  Rect r = best.get();
  ret r == null ? null : new FoundImg(r, 1-(-(float) best.bestScore())/(wp*hp));
}