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BWFILTER(1)			    BRL-CAD			   BWFILTER(1)

NAME
       bwfilter	- apply	a 3x3 filter to	a black	and white bw file

SYNOPSIS
       bwfilter	[-f type] [-v] [-d div]	[-o offset] [-s	squaresize] [-w	width]
		[-n height] [file.bw] _	newfile.bw

DESCRIPTION
       Bwfilter	applies	one of several 3x3 kernel filters to a black and white
       bw(5) format file. It will take a file name or else read	from standard
       input. The input	file size will be assumed to be	512x512	pixels unless
       the -s, -w, or -n flags are used	to tell	it otherwise (see brlcad(1)).
       By default a low	pass filter is used. The -f type flag can be used to
       specify a different type	of filter.

       The type	choices	include:

       lo
	   low pass, the default.

       hi
	   high	pass

       vg
	   vertical gradient

       hg
	   horizontal gradient

       la
	   laplacian

       b
	   boxcar low pass

       Most filters divide the result of the kernel multiplication by some
       value about in order to scale it	back to	a 0->255 range.	For example,
       the boxcar divides by nine. The -d flag can be used to change this
       divisor.	Some filters also add an offset	to their results. The output
       of a laplacian for example is "centered"	about zero, thus it adds 128
       to the answer to	yield a	difference from	neutral	grey. The -o flag can
       bw used to change this offset.

       The -v flag displays the	kernel values on standard error.

BUGS
       This should allow any 3x3 kernel	to be specified.

SEE ALSO
       brlcad(1), bwscale(1), bw(5).

AUTHOR
       BRL-CAD Team

COPYRIGHT
       This software is	Copyright (c) 1989-2013	by the United States
       Government as represented by U.S. Army Research Laboratory.

BUG REPORTS
       Reports of bugs or problems should be submitted via electronic mail to
       <devs@brlcad.org>.

BRL-CAD				  07/08/2017			   BWFILTER(1)

NAME | SYNOPSIS | DESCRIPTION | BUGS | SEE ALSO | AUTHOR | COPYRIGHT | BUG REPORTS

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