pgmenhance(1) General Commands Manual pgmenhance(1)NAME
pgmenhance - edge-enhance a portable graymap
SYNOPSIS
pgmenhance [-N] [pgmfile]
DESCRIPTION
Reads a portable graymap as input. Enhances the edges, and writes a portable graymap as output.
The edge enhancing technique is taken from Philip R. Thompson's "xim" program, which in turn took it from section 6 of "Digital Halftones
by Dot Diffusion", D. E. Knuth, ACM Transaction on Graphics Vol. 6, No. 4, October 1987, which in turn got it from two 1976 papers by J. F.
Jarvis et. al.
OPTIONS
The optional -N flag should be a digit from 1 to 9. 1 is the lowest level of enhancement, 9 is the highest, The default is 9.
SEE ALSO pgmedge(1), pgm(5), pbm(5)AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
13 January 1989 pgmenhance(1)
Check Out this Related Man Page
pgmedge(1) General Commands Manual pgmedge(1)NAME
pgmedge - edge-detect a portable graymap
SYNOPSIS
pgmedge [pgmfile]
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.
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 pnmdepth first.
SEE ALSO pgmenhance(1), pgmtopbm(1), pnmdepth(1), pgm(5), pbm(5)AUTHOR
Copyright (C) 1991 by Jef Poskanzer.
04 February 1990 pgmedge(1)
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