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Pamedge User Manual(0)					Pamedge User Manual(0)

NAME
       pamedge - edge-detect an image

SYNOPSIS
       pamedge [imagefile]

DESCRIPTION
       This program is part of Netpbm(1).

       pamedge	reads  a  Netpbm image (PNM or PAM) and produces an image that
       outlines the edges.

       The output image is of the same type as the input, except that the max‐
       val  of	the output is at least 255 and if the input is PBM, the output
       is PGM.

       You can pipe the result through pamditherbw -threshold  and  play  with
       the threshold value to get a PBM (bilevel image) 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.

       The  maxval  of	the  output is the same as the maxval of the input The
       effect is better with larger maxvals, so you may want to	 increase  the
       maxval of the input by running it through pamdepth first.

SEE ALSO
       pgmenhance(1),	 pamditherbw(1),    pamdepth(1),    pammasksharpen(1),
       pamsharpness(1), pamsharpmap(1), pam(1), pnm(1)

HISTORY
       pamedge was added to Netpbm in Release 10.14 (March 2003).  It replaced
       pgmedge,	 which	was  the  same	thing,	but worked only on PGM and PBM
       images.

AUTHOR
       Copyright  (C)  1991  by	 Jef  Poskanzer.   Adapted  to	pnmedge	 Peter
       Kichgessner in 1995, and then to pamedge by Bryan Henderson in 2003.

netpbm documentation		11 January 2003		Pamedge User Manual(0)

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