Export graphics to PPM.
xs2ppm(win_num, file_name)
xs2ppm(fig, file_name)
:win_num integer, id of the figure to export. : :fig handle of the figure to export. : :file_name string, name of the exported file. :
xs2ppm exports the display of a graphic window into a PPM file.
`scf`_(0)
`plot2d`_()
//PPM export
filename='foo.ppm';
xs2ppm(0,filename);