The PNM Format(5) File Formats Manual The PNM Format(5)
NAME
pnm - Netpbm superformat
DESCRIPTION
The PNM format is just an abstraction of the PBM, PGM, and PPM formats.
I.e. the name "PNM" refers collectively to PBM, PGM, and PPM.
The name "PNM" is an acronym derived from "Portable Any Map." This de-
rivation makes more sense if you consider it in the context of the other
Netpbm format names: PBM, PGM, and PPM.
The more general term "Netpbm format" refers to the PNM formats plus
PAM.
PNM is principally used with Netpbm(1).
Note that besides being names of formats, PBM, PGM, PPM, and PNM are
also classes of programs. A PNM program can take PBM, PGM, or PPM in-
put. That's nothing special -- a PPM program can too. But a PNM pro-
gram can often produce multiple output formats as well, and a PNM pro-
gram can see the difference between PBM, PGM, and PPM input and respond
to each differently whereas a PPM program sees everything as if it were
PPM. This is discussed more in the description of the netpbm programs"
(1).
"pnm" also appears in the names of the most general Netpbm library rou-
tines(1), some of which aren't even related to the PNM format.
INTERNET MEDIA TYPE
No Internet Media Type (aka MIME type, content type) for PNM has been
registered with the IANA, but the value image/x-portable-anymap is con-
ventional.
Note that there are also conventional Internet Media Types for each of
the PNM subformats. The recommended practice is to use those in prefer-
ence to the PNM code when it is convenient to do so.
FILE NAME
There are no requirements on the name of a PNM file, but the convention
is to use the suffix "pbm", "pgm", or "ppm", depending on the particular
subformat, or "pnm" if it is not convenient to distinguish the subfor-
mats.
SEE ALSO
ppm(1), pgm(1), pbm(1), pam(1), programs that process PNM(1), lib-
netpbm(1)
DOCUMENT SOURCE
This manual page was generated by the Netpbm tool 'makeman' from HTML
source. The master documentation is at
http://netpbm.sourceforge.net/doc/pnm.html
netpbm documentation 27 November 2013 The PNM Format(5)
Generated by dwww version 1.16 on Tue Dec 16 04:40:00 CET 2025.