pgmedge(1)              UNIX System V(04 February 1990)              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.

































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