sclass ChessOCR_Pipeline {
  replace Segmenter with IF1<BufferedImage, L<Rect>>.
  
  transient BufferedImage inputImage;
  new SeenAndQueue<Rect> possibleBoardPositions;
  new ChessOCR_BoardsFound boardsFound;
  ChessPieceRecognizer pieceRecognizer;
  transient ReliableSingleThread rstProcessPositions = new(r processPositions);
  
  // segmenters
  transient ReliableSingleThread rstRunSegmenters = new(r runSegmenters);
  new SeenAndQueue<Segmenter> segmenters;

  *() {
    possibleBoardPositions.onAddedToQueue(rstProcessPositions);
    segmenters.onAddedToQueue(rstRunSegmenters);
  }
  
  void addSegmenter(Segmenter s) {
    segmenters.add(s);
  }
  
  void addPossiblePosition(Rect r) {
    possibleBoardPositions.add(r);
  }
  
  // internal
  
  void processPositions() {
    Rect r;
    while not null (r = possibleBoardPositions.popQueue()) {
      ping();
      ChessOCR_RecognizedBoard board = pieceRecognizer.recognizeBoard(clipBufferedImage(inputImage, r));
      boardsFound.add(board);
    }
  }
  
  void runSegmenters() {
    Segmenter seg;
    while not null (seg = segmenters.popQueue()) {
      ping();
      for (Rect r : seg.get(inputImage))
        possibleBoardPositions.add(r);
    }
  }
  
  void cleanMeUp {
    // cancel the threads
    cleanUp(rstProcessPositions);
    cleanUp(rstRunSegmenters);
  }
}