sclass ChessPieceRecognizer {
  MultiMap<S, ChessPieceProfile1> profiles;
  new Map<S, Float> fillGradeThresholdsByPiece;
  
  void load {
    long time = sysNow();
    profiles = agiBlue_chessPieceProfiles();
    for (S piece : ai_6chessPieces()) {
      L<Float> w = collect fillGrade(profiles.get("white " + piece));
      L<Float> b = collect fillGrade(profiles.get("black " + piece));
      float white = floatAverage(w);
      float black = floatAverage(b);
      print("white/black " + piece + " avg: " + white + "/" + black);
      print("white/black " + piece + " min/max: " + floatMax(w) + "/" + floatMin(b));
      fillGradeThresholdsByPiece.put(piece, avg(white, black));
    }
    profiles = mapMultiMapKeys lastJavaToken(profiles); // drop color
    done2("Loading " + n2(l(profiles), "piece profile"), time);
  }
  
  Pair<S, Double> recognize(BufferedImage img) {
    ChessPieceProfile1 profile = chessOCR_pieceProfileFromRawImage_1(img);
    S piece, double score = unpair searchForMostSimilarByteArrayInMultiMap(profile.sideProfile, img);
    Float t = fillGradeThresholdsByPiece.get(piece);
    if (t != null)
      piece = (profile.fillGrade < t ? "white" : "black") + " " + piece;
    ret pair(piece, score);
  }
}