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>


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