Image Processing Reference
In-Depth Information
graphic images can be presented in a very appealing way. Several people have offered
improvements since then, and the basic technique is now used all over the world every
day to create high-quality images on systems with limited resources.
Figure 6-13 shows a photograph, followed by a simple threshold mapping from
grayscale to 1 bit and no dither. The third pane uses a pattern dither and the fourth uses
error diffusion.
Albie Dithering
The Albie dithering technique is specially designed to deal with images that are going to
be displayed on an interlaced monitor, which is what is required for TV imagery. The
dithering technique is very similar to the Floyd-Steinberg error diffusion algorithm. Albie
produces slightly better contrast but also exhibits some increased grain and contouring on
Original grayscale
50% threshold
Pattern dither
Diffusion dither
Figure 6-13 Error diffusion dithering.
Floyd-Steinberg derived algorithms:
Modified Floyd-Steinberg algorithm:
ACM Digital Library article: / citation.cfm?id=35039.35040
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