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PGMEDGE.MAN
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1991-08-11
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pgmedge(1) Unix Programmer's Manual pgmedge(1)
NNNAAAMMMEEE
pgmedge - edge-detect a portable graymap
SSSYYYNNNOOOPPPSSSIIISSS
pppgggmmmeeedddgggeee [_p_g_m_f_i_l_e]
DDDEEESSSCCCRRRIIIPPPTTTIIIOOONNN
Reads a portable graymap as input. Outlines the edges, and writes a
portable graymap as output. Piping the result through pppgggmmmtttooopppbbbmmm
---ttthhhrrreeessshhhooolllddd 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.
SSSEEEEEE AAALLLSSSOOO
pgmenhance(1), pgmtopbm(1), pgm(5), pbm(5)
AAAUUUTTTHHHOOORRR
Copyright (C) 1991 by Jef Poskanzer.
04 February 1990 1