ppmdither

Updated: 14 July 1991
Table Of Contents

NAME

ppmdither - ordered dither for color images

SYNOPSIS

ppmdither [-dim power] [-red shades] [-green shades] [-blue shades] [ppmfile]

DESCRIPTION

This program is part of Netpbm.

ppmdither 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.

You can do another kind of dither -- Floyd-Steinberg -- with pnmquant or pnmremap.

OPTIONS

-dim power: The size of the dithering matrix. The dithering matrix is a square whose dimension is a power of 2. power is that power of 2. The default is 4, for a 16 by 16 matrix.
-red shades: The number of red shades to be used, including black; minimum of 2.
-green shades: The number of green shades to be used, including black; minimum of 2.
-blue shades: The number of blue shades to be used, including black; minimum of 2.