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HALFTONE(1)			    BRL-CAD			   HALFTONE(1)

NAME
       halftone	- Translate a bw file to a halftoned bw	file

SYNOPSIS
       halftone	[-RSa] [-s squarefilesize] [-w file_width] [-n file_height]
		[-B contrast] [-I Number_Intensity_Levels] [-M Method]
		[-T Tone_Scale_Curve_Points] [-D debug_level] <	file.bw

DESCRIPTION
       halftone	reads a	bw(5) format file from the named file, or from
       standard	input if no file is specified, and reduces the number of
       intensity levels	from 256 to a default of 2.  halftone tries to
       preserve	as much	information as possible	by applying dither.

       By default, the bw file is assumed to be	512x512	pixels.

       If the -R flag is specified, random noise is added to the dither, and
       this can	sometimes improve the results.

       The -S flag causes a surpentine raster to be used rather	than a left to
       right scan.

       The -a flag is used when	automatic file sizing is wanted. This does not
       work on pipes.

       The -w file_width flag specifies	the width of each scanline in the
       input file, in pixels.

       The -n file_height flag specifies the height in scanlines of the	input
       file.

       -s squarefilesize sets both the height and width	to the size given.

       -B contrast will	define a floating point	value to be used as the	Beta
       portion of a edge sharpening algorithm. The default is 0.0, which is no
       sharpening.

       -I Levels defines the number of different intensity levels to use on
       output. The default is 2	(1 bit)	and the	max is 256 (8 bits).

       -M method allows	a choice of dither methods. The	default	is 0 a
       Floyd-Steinberg diffused	error dither, 1	is a 45	degree classical
       clustered halftone screen, 2 is a simple	threshold dither, 3 is a 0
       degree dispersed	halftone screen.

       The -T x1 y1 x2 y2 ...  parameter is used to define a curve to be used
       as a tone scale.	The resulting curve is used to map input pixels	to
       output pixels. The default curve	is -T 0	0 128 128 255 255; a curve
       suggested by Robert Ulichney in Digital Halftoning is -T	0 0 15 0 128
       100 200 200 240 255 255 255.

       -D debug_level supplies the debug level;	setting	the argument to	9
       provides	all debugging.

FORMAT
       A bw(5) file contains sequences of pixels. Each pixel is	stored as one
       unsigned	char.  The first pixel in a bw file is the lower left corner
       of the image. The pixels	proceed	from left-to-right across each
       scanline, with scanlines	being written from the bottom to the top of
       the image.

       The output from halftone	is scaled so that each intensity level is
       output as 255/Levels*value.

SEE ALSO
       rt(1), pix-bw(1), bw(5),	bw-fb(1)

AUTHOR
       BRL-CAD Team

COPYRIGHT
       This software is	Copyright (c) 1990-2019	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			   HALFTONE(1)

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

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