pgmedge(1)               USER COMMANDS                 pgmedge(1)



NAME
     pgmedge - edge-detect a portable graymap

SYNOPSIS
     pgmedge [_p_g_m_f_i_l_e]

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.

































Sun Release 4.0   Last change: 04 February 1990                 1