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BWDIFF(1)			    BRL-CAD			     BWDIFF(1)

NAME
       bwdiff -	compare	two black and white files

SYNOPSIS
       bwdiff [- [mglen]] [-b] file1 file2

DESCRIPTION
       bwdiff compares two black and white bw(5) format	files in one of
       several ways, and writes	the results on standard	out. The default
       method of comparison is to record the differences as offsets from
       neutral,	half-intensity grey (128). The value written will be brighter
       than this neutral grey by an amount proportional	to the signed
       difference between the pixels in	file1 and file2. That is, pixels which
       are brighter in file1 than in file2 will	be brighter than the neutral
       grey, while pixels which	are dimmer in file1 than in file2 will be
       dimmer. This difference is divided by two so that the results will fit
       in the 0->255 output range.

       The -m flag takes the magnitude of the difference, thus no offset or
       divide is necessary. Brighter pixels indicate larger differences	in
       value. Black indicates no difference in value.

       The flags -g -l -e and -n are relational	operations, standing for
       greater-than, less-than,	equal-to, and not-equal-to respectively. Only
       one of these flags may be used at a time. In this mode the value	of a
       pixel in	the first file is compared to the corresponding	pixel in the
       second, and if the relation is true, a full-white (255) pixel is
       output. This mode is useful for producing masks showing pixels which
       satisfy the given condition. The	default	background is black, unless
       the -b option is	specified, is which case the background	is file1, with
       a lowered intensity.

       bwdiff accepts ``-'' as a synonym for stdin, and	``.'' as a synonym for
       /dev/null .

       Note that this program also produces useful results on color pix(5)
       files.

EXAMPLE
       Suppose you ran pixstat(1) on a file and	found the modes	to be red=107,
       green=93, blue=70. You could display those pixels whose colors are at
       these values by:

       gencolor	107 93 70 | bwdiff -e file.pix - | pix-fb

SEE ALSO
       brlcad(1), pixdiff(1), bwstat(1), bw(5),	pix(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			     BWDIFF(1)

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

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