sclass ChessOCR_Pipeline {

  replace Segmenter with IF1<BufferedImage, L<Rect>>.

  // input

  transient BufferedImage inputImage;

  ChessPieceRecognizer pieceRecognizer;

  // internal

  SeenAndQueue<Segmenter> segmenters = new(r _runSegmenters);

  SeenAndQueue<Rect> possibleBoardPositions = new(r _processPositions);

  // output

  new ChessOCR_BoardsFound boardsFound;

  // input segmenters & board position proposals:

  void addSegmenter(Segmenter s) { segmenters.add(s); }

  void addPossiblePosition(Rect r) { possibleBoardPositions.add(r); }

  bool queuesEmpty() { ret segmenters.queueEmpty() && possibleBoardPositions.queueEmpty(); }

  bool idle() { ret segmenters.idle() && possibleBoardPositions.idle(); }

  // internal

  void _processPositions() {

    for (Rect r : possibleBoardPositions.queueIterator())

      boardsFound.add(setAll(pieceRecognizer.recognizeBoard(clipBufferedImage(inputImage, r)), rectInOriginalImage := r));

  }

  void _runSegmenters() {

    for (Segmenter seg : segmenters.queueIterator())

      possibleBoardPositions.addAll(seg.get(inputImage));

  }

  void cleanMeUp { // cancels the threads too

    cleanUpAll(possibleBoardPositions, segmenters);

  }

}