ctory structure.  Note: because jpeg is
      a supported tiff compression mode, leptonica requires linking
      both libtiff and libjpeg to read and write tiff.  See tiffio.c

    - BMP has (until recently) had no compression.  It is a simple
      format with colormaps that requires no external libraries.
      It is commonly used because it is a Microsoft standard,
      but has little besides simplicity to recommend it.  See bmpio.c.

    - PNM is a very simple, old format that still has surprisingly
 