.TL
Ppmdither User Manual
.SH 1
ppmdither
.LP
Updated: 14 July 1991
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Table Of Contents
.SH 2
NAME
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ppmdither - ordered dither for color images
.SH 2
SYNOPSIS
.LP
\fBppmdither\fR
[\fB-dim\fR \fIpower\fR]
[\fB-red\fR \fIshades\fR]
[\fB-green\fR \fIshades\fR]
[\fB-blue\fR \fIshades\fR]
[\fIppmfile\fR]
.SH 2
DESCRIPTION
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.LP
This program is part of Netpbm.
.LP
\fBppmdither\fR reads a PPM 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.  The default number of shades is red=5,
green=9, blue=5, for a total of 225 colors.  To convert the image to a
binary rgb format suitable for color printers, use -red 2 -green 2
-blue 2.
.LP
You can do another kind of dither -- Floyd-Steinberg -- with 
\fBpnmquant\fR or \fBpnmremap\fR.
.SH 2
OPTIONS
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.RS
.IP "\fB-dim\fR \fIpower\fR"
 The size of the dithering matrix.  The dithering matrix is a
square whose dimension is a power of 2.  \fIpower\fR is that power of
2.  The default is 4, for a 16 by 16 matrix.
.IP "\fB-red\fR \fIshades\fR"
The number of red shades to be used, including black; minimum of 2.
.IP "\fB-green\fR \fIshades\fR"
The number of green shades to be used, including black; minimum of 2.
.IP "\fB-blue\fR \fIshades\fR"
The number of blue shades to be used, including black; minimum of 2.
.RE
.SH 2
SEE ALSO
.LP
pamdepth,
pnmquant,
pnmremap
ppm
.SH 2
AUTHOR
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Copyright (C) 1991 by Christos Zoulas.
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\l'5i'
.SH 2
Table Of Contents
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SYNOPSIS
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DESCRIPTION
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OPTIONS
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AUTHOR
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