code: @Override
      public String doOCR(int xsize, int ysize, ByteBuffer buf, Rectangle rect, int bpp) throws TesseractException {
          return doOCR(xsize, ysize, buf, null, rect, bpp);
      }
docs: Performs OCR operation. Use <code>SetImage</code>, (optionally)
  <code>SetRectangle</code>, and one or more of the <code>Get*Text</code>
  functions.
  
  @param xsize width of image
  @param ysize height of image
  @param buf pixel data
  @param rect the bounding rectangle defines the region of the image to be
  recognized. A rectangle of zero dimension or <code>null</code> indicates
  the whole image.
  @param bpp bits per pixel, represents the bit depth of the image, with 1
  for binary bitmap, 8 for gray, and 24 for color RGB.
  @return the recognized text
  @throws TesseractException