scaling and placing of images, and for printing at different
   resolutions.  You can also compose mixed raster (text, image) PS.
   See psio1.c for examples of how to output PS for different applications.
   As examples of usage, see:
     * prog/converttops.c for a general image --> PS conversion
           for printing.  You can specify the PS compression level (1, 2, or 3).
     * prog/imagetops.c for a special image --> PS conversion
           for printing at maximum size on 8.5 x 11 paper.  You can
 