dvips: Dynamic creation of graphics

 
 5.1.5 Dynamic creation of PostScript graphics files
 ---------------------------------------------------
 
 PostScript is an excellent page description language--but it does tend
 to be rather verbose.  Compressing PostScript graphics files can reduce
 them by factor of five or more.  For this reason, if the name of an
 included PostScript file ends with '.Z' or '.gz', Dvips automatically
 runs 'gzip -d'.  For example:
 
      \epsffile[72 72 540 720]{foo.ps.gz}
 
 Since the results of such a command are not accessible to TeX, if you
 use this facility with the 'epsf' macros, you need to supply the
 bounding box parameter yourself, as shown.
 
    More generally, if the filename parameter to one of the graphics
 inclusion techniques starts with a left quote ('`'), the parameter is
 instead interpreted as a command to execute that will send the actual
 file to standard output.  For example:
 
      \special{psfile="`gnuplot foo"}
 
 to include the file 'foo'.  Of course, the command to be executed can be
 anything, including using a file conversion utility such as 'tek2ps' or
 whatever is appropriate.  This feature can be disabled with the '-R'
 command-line option or 'R' configuration option.