PNMARITH

NAME

      pnmarith - perform arithmetic on two portable anymaps

SYNOPSIS

      pnmarith -add|-subtract|-multiply| 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>