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: ----
  (...)
  
  PdfTableSettings settings = PdfTableSettings.getBuilder()
                  .setCannyFiltering(true)
                  .setCannyApertureSize(5)
  
negative.code:                 .setPdfRenderingDpi(160)
                  .build();
  
  // pass settings to reader
  PdfTableReader reader = new PdfTableReader(settings);
  ----
  
  