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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] [-o	out_file] [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
       be used to change this offset.

       The -v flag displays the	max and	minimum	values and the kernel
       information 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) 1989-2019	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				  03/02/2021			   BWFILTER(1)

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

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