1Pamedge User Manual(0)                                  Pamedge User Manual(0)
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NAME

6       pamedge - edge-detect an image
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SYNOPSIS

10       pamedge [imagefile]
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DESCRIPTION

14       This program is part of Netpbm(1).
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16       pamedge  reads  a  Netpbm image (PNM or PAM) and produces an image that
17       outlines the edges.
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19       The output image is of the same type as the input, except that the max‐
20       val  of  the output is at least 255 and if the input is PBM, the output
21       is PGM.
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23       You can pipe the result through pamditherbw -threshold  and  play  with
24       the threshold value to get a PBM (bilevel image) of the edges.
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26       The edge detection technique used is to take the Pythagorean sum of two
27       Sobel gradient operators at 90 degrees to each other.  For more details
28       see 'Digital Image Processing' by Gonzalez and Wintz, chapter 7.
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30       The maxval of the output is the same as the maxval of the input, except
31       at least 255.  The effect is better with larger  maxvals,  so  you  may
32       want to increase the maxval of the input by running it through pamdepth
33       first.
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SEE ALSO

37       pgmenhance(1),    pamditherbw(1),    pamdepth(1),    pammasksharpen(1),
38       pamsharpness(1), pamsharpmap(1), pam(1), pnm(1)
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HISTORY

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

49       Copyright  (C)  1991  by  Jef  Poskanzer.   Adapted  to  pnmedge  Peter
50       Kichgessner in 1995, and then to pamedge by Bryan Henderson in 2003.
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54netpbm documentation            11 January 2003         Pamedge User Manual(0)