GIMPPRINT-DITHERS(7) Gimp-Print Manual Pages GIMPPRINT-DITHERS(7)
gimpprint-dithers - Gimp-Print dither algorithms
Gimp-Print includes several dither algorithms. Dithering attempts to reproduce various
shades of gray (or all colors) from only a few different inks (black, cyan, magenta, yel-
low, and sometimes light cyan and light magenta). The dots can't vary in darkness or size
(except for certain special printers), and so we need to lay down a certain fraction of
dots to represent each distinct level. Different dither algorithms are suited to differ-
ent purposes, and some are significantly faster than others.
Dither Algorithm Description
Adaptive Adaptive Hybrid
EvenTone EvenTone screening (experimental)
VeryFast Very Fast
Floyd Hybrid Floyd-Steinberg
For the highest quality, we recommend use of Adaptive Hybrid dithering. For continuous
tone images, Ordered works just as well and is somewhat faster. Ordered dithering yields
noticeably inferior results with text and intricate line art, particularly at high resolu-
EvenTone dithering is a relatively new screening technology developed by Raph Levien. It
offers superior smoothness in highlights and midtones, and increased accuracy in shadows,
resulting in significantly improved results overall. The version of EvenTone dithering
that we are using is enhanced with some additional improvements we have made. It cur-
rently only operates with CMYK (4, 6, or 7 color output) with RGB input, and should be
considered experimental. Note that it is patented (see US patent 5917614), but it is
licensed for use with GPL software. See http://www.levien.com/patents.html for more
Fast dithering, which is a simplified version of ordered dither, is significantly faster,
but color accuracy is worse, particularly on six color printers and printer using variable
dot sizes. On simple four color printers, the quality is quite reasonable, although color
printing will show more speckling in dark tones than Ordered dither. For single dot size
printers, printing grayscale, this algorithm yields almost identical results to Ordered
with some performance improvement. On three color printers, the results should be very
similar to Ordered.
Very Fast is even faster than Fast, with even more loss of quality. It shows even more
speckling, and the output is heavily patterned. On laser printers, and possibly on cer-
tain kinds of text and line art, Very Fast dithering may actually yield the best quality.
Error diffusion algorithms (Hybrid Floyd-Steinberg is such an algorithm) perform very well
at high densities, and are capable of rendering very fine detail well, but they tend to
exhibit artifacts in the form of "waves" or "worms" of dots which results in noticeable
texturing in pale areas. Furthermore, pale areas immediately adjacent to white take a
while to "build up" sufficient error to print at all. This is sometimes called "tearing".
Its use is not recommended.
Copyright (C) 2001 Michael Sweet (email@example.com) and Robert Krawitz (firstname.lastname@example.org)
This program is free software; you can redistribute it and/or modify it under the terms of
the GNU General Public License as published by the Free Software Foundation; either ver-
sion 2 of the License, or (at your option) any later version.
This manual page was written by Roger Leigh (email@example.com)
gimpprint-color(7), gimpprint-imagetypes(7), gimpprint-inktypes(7), gimpprint-media-
sizes(7), gimpprint-mediasources(7), gimpprint-mediatypes(7), gimpprint-models(7), gimp-
Version 4.2.4 25 Nov 2002 GIMPPRINT-DITHERS(7)