ppmdither(1) ppmdither(1)
**NAME**
ppmdither - ordered dither for color images
**SYNOPSIS**
**ppmdither** [**-dim** *dimension*] [**-red** *shades*] [**-green** *shades*]
[**-blue** *shades*] [*ppmfile*]
**DESCRIPTION**
Reads a portable pixmap as input, and applies dithering to
it to reduce the number of colors used down to the speci-
fied number of shades for each primary. The default num-
ber 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.
The maximum number of colors that can be used is 256 and
can be computed as the product of the number of red, green
and blue shades.
**OPTIONS**
**-dim** *dimension*
The size of the dithering matrix. Must be a
power of 2.
**-red** *shades* The number of red shades to be used; minimum
of 2.
**-green** *shades* The number of green shades to be used; mini-
mum of 2.
**-blue** *shades* The number of blue shades to be used; mini-
mum of 2.
**SEE** **ALSO**
pnmdepth(1), ppmquant(1), ppm(5)
**AUTHOR**
Copyright (C) 1991 by Christos Zoulas.
14 July 1991 1