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