\
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.TH "Ppmdither User Manual" 1 "16 December 2009" "netpbm documentation"

.SH NAME
ppmdither - ordered dither for color images

.UN synopsis
.SH SYNOPSIS

\fBppmdither\fP

[\fB-dim\fP=\fIpower\fP]

[\fB-red\fP=\fIn\fP]

[\fB-green\fP=\fIn\fP]

[\fB-blue\fP=\fIn\fP]

[\fInetpbmfile\fP]
.PP
All options can be abbreviated to their shortest unique prefix.
You may use two hyphens instead of one to designate an option.  You
may use either white space or an equals sign between an option name
and its value.


.UN description
.SH DESCRIPTION
.PP
This program is part of
.BR "Netpbm" (1)\c
\&.
.PP
\fBppmdither\fP reads a Netpbm image as input, and applies dithering
to it to reduce the number of colors used down to the specified number
of shades for each primary.  It produces a PPM image as output.
.PP
The default number of shades is 5 red, 9 green, and 5 blue, for a total of
225 colors.  To convert the image to a binary rgb format suitable for
primitive color printers, use \fB-red=2 -green=2 -blue=2\fP.
.PP
You can do another kind of dither -- Floyd-Steinberg -- with 
\fBpnmquant\fP or \fBpnmremap\fP.

.UN options
.SH OPTIONS
.PP
In addition to the options common to all programs based on libnetpbm
(most notably \fB-quiet\fP, see 
.UR index.html#commonoptions
 Common Options
.UE
\&), \fBppmdither\fP recognizes the following
command line options:


.TP
\fB-dim\fP \fIpower\fP
 The size of the dithering matrix.  The dithering matrix is a
square whose dimension is a power of 2.  \fIpower\fP is that power of
2.  The default is 4, for a 16 by 16 matrix.

.TP
\fB-red\fP=\fIn\fP
The number of red shades to be used, including black; minimum of 2.
.sp
Default is 5.

.TP
\fB-green\fP \fIn\fP
The number of green shades to be used, including black; minimum of 2.
.sp
Default is 9.

.TP
\fB-blue\fP \fIn\fP
The number of blue shades to be used, including black; minimum of 2.
.sp
Default is 5.


.UN seealso
.SH SEE ALSO
.BR "pamditherbw" (1)\c
\&,
.BR "pamdepth" (1)\c
\&,
.BR "pnmquant" (1)\c
\&,
.BR "pnmremap" (1)\c
\&,
.BR "ppm" (1)\c
\&

.UN author
.SH AUTHOR

Copyright (C) 1991 by Christos Zoulas.
.SH DOCUMENT SOURCE
This manual page was generated by the Netpbm tool 'makeman' from HTML
source.  The master documentation is at
.IP
.B http://netpbm.sourceforge.net/doc/ppmdither.html
.PP