pnmarith(1) pnmarith(1)
**NAME**
pnmarith - perform arithmetic on two portable anymaps
**SYNOPSIS**
**pnmarith** **-add**|**-subtract**|**-multiply**|**-difference**|**-mini-**
**mum**|**-maximum.** *pnmfile1* *pnmfile2*
**DESCRIPTION**
Reads two portable anymaps as input. Performs the speci-
fied arithmetic operation, and produces a portable anymap
as output. The two input anymaps must be the same width
and height.
The arithmetic is performed between corresponding pixels
in the two anymaps, as if maxval was 1.0, black was 0.0,
and a linear scale in between. Results that fall outside
of [0..1) are truncated.
The operator *-difference* calculates the absolute value of
*pnmarith* *-subtract* *pnmfile1* *pnmfile2,* i.e. no truncation
is done.
All flags can be abbreviated to their shortest unique pre-
fix.
**SEE** **ALSO**
pbmmask(1), pnmpaste(1), pnminvert(1), pnm(5)
**AUTHOR**
Copyright (C) 1989, 1991 by Jef Poskanzer. Lightly modi-
fied by Marcel Wijkstra <wijkstra@fwi.uva.nl>
26 August 1993 1