PGMENHANCE

NAME

      pgmenhance - edge-enhance a portable graymap

SYNOPSIS

      pgmenhance [-N] [pgmfile]

DESCRIPTION

      Reads a portable graymap as input.  Enhances the edges, and writes a
      portable graymap as output.  The optional -N argument should be a
      digit from 1 to 9.  1 is the lowest level of enhancement, 9 is the
      highest, The default is 9.
      The edge enhancing technique is taken from Philip R. Thompson's "xim"
      program, which in turn took it from section 6 of "Digital Halftones by
      Dot Diffusion", D. E. Knuth, ACM Transaction on Graphics Vol. 6, No.
      4, October 1987, which in turn got it from two 1976 papers by J. F.
      Jarvis et. al.

DEMONSTRATION

      Let a.pgm be a portable graymap.
      The following command will edge-enhance it(with an enhancement level of 5):
	pgmmerge pgmenhance -5 a.pgm >aee.pgm

BEFORE

AFTER

enhancement level of 1:

enhancement level of 5:

enhancement level of 9:

SEE ALSO

      pgm(5), pbm(5)

AUTHOR

      Copyright (C) 1989 by Jef Poskanzer.
      Permission to use, copy, modify, and distribute this software and its
      documentation for any purpose and without fee is hereby granted,
      provided that the above copyright notice appear in all copies and that
      both that copyright notice and this permission notice appear in
      supporting documentation.  This software is provided "as is" without
      express or implied warranty.