pgmedge(1)

NAME

       pgmedge - edge-detect a portable graymap

SYNOPSIS

       pgmedge [pgmfile]

DESCRIPTION

       Reads  a  portable  graymap as input.  Outlines the edges, and writes a
       portable  graymap  as  output.   Piping  the  result  through  pgmtopbm
       -threshold  and  playing with the threshold value will give a bitmap of
       the edges.

       The edge detection technique used is to take the Pythagorean sum of two
       Sobel gradient operators at 90 degrees to each other.  For more details
       see "Digital Image Processing" by Gonzalez and Wintz, chapter 7.

SEE ALSO

       pgmenhance(1), pgmtopbm(1), pgm(5), pbm(5)

AUTHOR

       Copyright (C) 1991 by Jef Poskanzer.

                               04 February 1990                     pgmedge(1)