🚀 go-pugleaf

In article <arctngnt.1470@amiganet.chi.il.us> arctngnt@amiganet.chi.il.us (Bowie J Poag) writes:
->
->Dithering is how to make a shade of color from two or more seperate colors. 
->For instance, pick up a newspaper.. Youll see that greys are NOT infaCt grey
->ink.. But rather black and white dots. This is an example of pretty simple
->dithering..
->
->You can simulate green by putting a yellow pixel, and a blue pixel next to
->eachother... get up to your TV sometime, and look real close at it. All the
->colors you see are represented by differing amounts of red, green abd blue
->little lights. Every color in the spectrum is composed of differing amounts of
->red green and blue..
->
What you see on your newspaper is in fact halftoning, where gray shades are 
made up of black dots of varying size, aranged in a regular pattern called a 
"screen".  TVs produce colors by a similar technique, modulating the luminosity
of the RBG phoshor dots.  Neither of these is an example of dithering.
[...]
->
->Arc
->(Now, Whats quantifying? Even I dont know that one..Does it have room for
->Jell-O?)

>Newspaper print is a VERY good example of
>dithering. Why pictures in newspapers appear to be grey, yes, is infact the
>size of the BLACK dots next to WHITE spaces.

Newspaper is halftoning which I would guess is a specialized case of
dithering. 

>Television is a VERY good example of dithering as well.. If your TV screen
>was white, and you moved up real close to the TV screen, youde see a bunch of
>red green and blue dots..

Hmmm I'm not so sure this is a VERY good example of dithering. The spots
on a TV are analog and you are varying the intensity of the spots only
where most dithering is normally a variation of spot size and angle but
not the intensity.

When you simulate 16 million colors on an Amiga screen with the 4000 colours
available, you dither the colours you have to simulate more colours. Is this
then dithering the dithering?


>
>If youre TV screen was an aqua color. Youde lean up to the screen and see only
>blue and green dots.
>
>
>Think, bud. THINK.
>Arc

There seems to be some confusion as to the difference between dithering and
halftoning.  Newspapers are halftoned, with different sized dots, while TV is
dithered.  In dithering, a pattern of pixels is used to simulate a color by
having the visual system combine (usually different) individual colors into a
color not readily obtainable.

I'm rather new to this newsgroup, and have a question.  Are personal attacks
and smug remarks commonplace, or is this a place to try to work together to
advance the state of multimedia systems?  I hope that it is the latter, because
there is a real need for such a group.  If it is the former, then we are wasting
a lot of bandwidth for hot air.

A question about all this dithering business:
It seems that the process that I always called rasterizing (i.e.
turning a greyscale image into dots) is officially called halftoning.
I assume that this is the name for the photographic process, i.e. where
you end up with large and small dots.

Now, what is the name for the process you use on, say, laserprinters,
where you end up with dots of a single size, but vary the number of
them to get the correct greyness of an image?
-- 
--
Een volk dat voor tirannen zwicht	| Oral:     Jack Jansen
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dan dooft het licht			| Uucp:     hp4nl!cwi.nl!jack

When I was in the Electronic Imaging in Ahn Heim in May, I saw
a product (sorry I forgot the name) which showed the live video 
in the window, and I could resize the window in either horizontal 
or vertical direction as I want continuously. 

Well I could imagine how it could be done if I want to resize the 
wnidow in the multiple of 2 or only in the horizontal direction.
But I can't think of the method to resize the window in vertical 
direction. It seems that they are using the anlalog technique to 
do this. Any idea about this? (Please forgive my ignorance if
this is silly question)

Thanks in advance.

-- 

Dong-Lok Kim

ICSL (Image Computing System Lab)