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This program is part of Netpbm.
pgmnoise creates a PGM image that is made up of pixels of random brightness.
This program exists for backward compatibility and is implemented as a thin wrapper around pamnoise, which is what you should use in any new applications. pamnoise is a drop-in replacement for pgmnoise except that it produces PAM output instead of PGM. If you must have PGM output, put the output through pgmtopgm (but you probably don't have to, because most Netpbm programs that accept PGM input also accept equivalent PAM input; in some cases, you may need to add a -tupletype=GRAYSCALE option).
Use the pamnoise manual with pgmnoise, with the following exceptions:
The original pgmnoise was written by Frank Neumann in 1993 and added to Netpbm at that time.
It was significantly enhanced and rewritten in the years following, including to use Netpbm's new random number architecture developed by Akira Urushibata, until pamnoise replaced it in Netpbm 11.16 (September 2026) and pgmnoise was replaced with a thin wrapper around pamnoise.