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.