d from memory
   and write to memory.  The gnu C runtime library (glibc) supports
   two I/O functions, open_memstream() and fmemopen(), which read
   and write directly to memory as if writing to a file stream.
     * On all platforms, leptonica supports direct read/write with memory
       for TIFF, PNG, BMP, GIF and WEBP formats.
     * On linux, leptonica uses the special gnu libraries to enable
       direct read/write with memory for JPEG, PNM and JP2.
     * On platforms without the gnu libraries, su