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From: dale@lamont.ldgo.columbia.edu (dale chayes)
Newsgroups: comp.sys.sgi
Subject: Re: Who needs 24 bit colors
Summary: He is lucky.
Message-ID: <3569@lamont.ldgo.columbia.edu>
Date: 4 Apr 91 20:37:55 GMT
References: <9104032223.AA03789@karron.med.nyu.edu>
Organization: Lamont-Doherty Geological Observatory N.Y.
Lines: 48

In article <9104032223.AA03789@karron.med.nyu.edu>, 
Dan Karron@UCBVAX.BERKELEY.EDU transcribed an article that appeared in:

> Photonics Spectra, April 1991, Page 119 by Kendal Preston, Jr. 

Who contends that for his application in some kind of
photomicrography, 8 bit color and clever use of dynamic compression
was sufficient.

Dan closed with:

> What do you think?


I don't know much about the dynamic range of photomicrographs, but if
that was his one and only test case before decreeing that there was no
need for displays with more dynamic range than that allowed by 8-bit
color, then it seems to me not only might his system for obtaining the
color images be of limited dynamic range, but perhaps his imagination
is suffering from a similar problem.

We can easily map the ocean floor to a resolution of a meter or two
(lets skip accuracy for the moment) over a range of 10km we need more
than eight bits if we want to color code never mind if we want to add
additional coding for lithology or backscatter function of the
seafloor, or muck around with 3D projections and lighting models.

For some applications, all we care about is the coding (by color in
this case) of the characteristics of one specific image. However, in
many others, we want to color code a whole universe and be able to
visualy compare one image to another in some kind of abosolute scale.
That (in my opinion is where we need the dynamic range.)


Dale
========
"Since we don't don't have much in the way of official policy here
other than the recent edict about dogs in the administration building,
we certainly can't have official opinion, so this must be my
fault...."



-- 
Dale Chayes Lamont-Doherty Geological Observatory of Columbia University
Route 9W, Palisades, N.Y.  10964	dale@lamont.ldgo.columbia.edu
voice:	(914) 359-2900 extension 434	fax: (914) 359-6817