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netpbm_10.0-12ubuntu1_i386 **NAME**

pnmarith - perform arithmetic on two portable anymaps

**SYNOPSIS**

**pnmarith** **-add**|**-subtract**|**-multiply**|**-difference**|**-minimum**|**-maximum.**
__pnmfile1__ __pnmfile2__

**DESCRIPTION**

Reads two portable anymaps as input. Performs the specified 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 prefix.

**SEE** **ALSO**

pbmmask(1), pnmpaste(1), pnminvert(1), pnm(5)

**AUTHOR**

Copyright (C) 1989, 1991 by Jef Poskanzer. Lightly modified by Marcel
Wijkstra <wijkstra@fwi.uva.nl>
26 August 1993 pnmarith(1)