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



Table Of Contents


NAME
       pamedge - edge-detect an image


SYNOPSIS
       pamedge [imagefile]


DESCRIPTION
       This program is part of Netpbm(1).

       pamedgereads 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 maxval 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 run-
       ning it through pnmdepth first.


SEE ALSO
       pgmenhance(1),   pamditherbw(1),    pnmdepth(1),    pam-
       masksharpen(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)
