References for Multibit Dithering wanted

References for Multibit Dithering wanted

Post by P. Bahl (Vict » Thu, 21 Feb 1991 05:05:35



Hi:

I am looking for references on multibit dithering (Ordered and/or Error
Diffusion).  I am interested in papers/articles that specifically talk
about Multibit dithering as opposed to going to binary displays.

Any pointers would be helpfull and appreciated

Thanks

Victor Bahl

 
 
 

References for Multibit Dithering wanted

Post by Jeffrey Mullig » Fri, 22 Feb 1991 07:32:14



Quote:>I am looking for references on multibit dithering (Ordered and/or Error
>Diffusion).

There is a very simple method for the special case where the
grey scale is to be quantized uniformly (equal steps):

Say you want to quantize to N levels, and that the input
is normalized to a min of 0 and a max of N-1.  First quantize
the image to N-1 levels by rounding down, resulting in an
integer image ranging from 0 to N-2.  (To insure that no
pixels get quantized to N-1 you have to tweak the normalization
so that the max is slightly less than N-1).  Now subtract the
quantized image from the original, which results in a non-negative
error image ranging from 0 to 1.  Apply your favorite binary
dithering algorithm to this error image.  Now add the dithered
error image to the quantized (truncated) image, with the "on"
pixels in the dithered error image "promoting" selected pixels
in the quantized image to the next level.

I discussed this briefly in an SPIE paper from 1990 (of which I
have reprints).  There are also other, more complex algorithms
which can deal with nonuniform quantization and arbitrary
color palettes, for which I cannot supply references off-hand.
For arbitrary color palettes, this usually boils down to
finding the "best" color; there are two halves to the problem:
the search (maybe it can be restricted), and deciding what
metric to use to decide which of two palette colors is "closer"
to the target color.  General formulas for characterizing
perceptual color differences is an active area of psychophysical
research.

--


        NASA/Ames Research Ctr., Mail Stop 262-2, Moffett Field CA, 94035
        (415) 604-3745

 
 
 

1. Wanted: Good references in SPATIAL DITHERING

Any better or more recent reference on spatial dithering than the following?

Robert A. Ulichney "Dithering with blue noise",
Proc. IEEE, vol. 76, no.1, jan 1998

Thanks in advance,

Erik

--
Erik Simonsen, ESA/ESTEC WDP                __  __   _  European
Postbus 299, 2200 AG Noordwijk             /_  (_   /_| Space
Phone: +31 1719 3133 Fax: +31 1719 84295  /__  __) /  | Agency

2. OpenGL vs DirectX

3. Help wanted on dithering images. (dithering technique)

4. Vignette help

5. Looking for references to cool dithering algos

6. Colors

7. Need reference for dithering

8. How to install a screen font?

9. References sought on Dithering

10. Dithering References

11. COLOR DITHERING REFERENCES?

12. Need references for Floyd-Steinberg dithering algorithm