anchor.diff:  
   . Page is converted to grayscale image [OpenCV].
   . Binary Inverted Threshold (BIT) is applied to grayscaled image [OpenCV].
  -. Contours are detected on BIT image and contour mask is created [OpenCV].
  +. Contours are detected on BIT image and contour mask is created (additional Canny filtering can be turned on in this step) [OpenCV].
   . Contour mask is XORed with BIT image [OpenCV].
  -. Contours are detected once again on XORed image [OpenCV].
  +. Contours are detected once again on XORed image (additional Canny filtering can be turned on in this step) [OpenCV].
   . Final contours are drawn [OpenCV].
   . Bounding rectangles are detected from final contours [OpenCV].
   . PDF is being parsed region-by-region using bounding rectangles coordinates [Apache PDFBox].
  
positive.code:                 .setPdfRenderingDpi(160)
                  .build();
  
  PdfTableReader reader = new PdfTableReader(settings);
  ----
  
  
negative.code:             futures.add(executor.submit(callable));
          }
  
          // collect parsed pages
          List<ParsedTablePage> unsortedParsedPages = new ArrayList<>(pdfDoc.getNumberOfPages());
          try {
              for (Future<ParsedTablePage> f : futures) {
  