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pgmedge.1
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1994-08-27
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pgmedge(1) USER COMMANDS pgmedge(1)
NAME
pgmedge - edge-detect a portable graymap
SYNOPSIS
pgmedge [_✓p_✓g_✓m_✓f_✓i_✓l_✓e]
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.
Sun Release 4.0 Last change: 04 February 1990 1