Convert pbmplus files to and from S objects
USAGE: 
get.pgm.image(file)
put.pgm.image(x, file)
file:
a character string specifying the file.
x:
an S image object.
VALUE:
a file containing an image of the pgm type from the pbmplus image processing package is either converted to an S image object (get.pgm.image()) or written to contain a copy of such an object (put.pgm.image()). These functions are primarily support and should not be needed in typical use of the pbmplus interface.
REFERENCE:
John M. Chambers and Neil Crellin, "Images in S" AT&T Bell Laboratories Stat. Res. Report No. 100 (Dec. 1991)