Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!sco!brianm
From: brianm (Brian Moffet)
Newsgroups: comp.sys.amiga
Subject: Re: 24/32 Bit Color
Message-ID: <U=A.656352743@sco>
Date: 19 Oct 90 16:12:23 GMT
References: <33786@nigel.ee.udel.edu>
Sender: news@sco.COM
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byrne@muppet.dnet.ge.com writes:


>I think I need some education.  I was under the (false?) assumption that the
>human eye could not distinguish 16 million colors (24 bit).  I assumed 24 bits
>was decided as number because it was an even multiple of a byte given the 3
>color components (RGB).  Since most displays don't have 16 million pixels, this
>gives you a great big palette.  But why 32 bit?  Is 32 bit color used because
>it is the word size of most of the popular high performance microprocessors
>(i.e 68020+)?  I don't see it buying you anything from a color stand point
>because who could distinguish adjacent colors from either 24 or 32 bit
>palettes?  Does it help in shading or is it just for data movement speed?

Well, this is an intresting topic in psycho-bioliogy.  You see,
with 24 bits of RGB triples, assuming 8 bits each, you have
only 256 colors of red, green, and blue.

Now, for most applications, this does very well.  However, when you
are trying to model low-light situations, you get into trouble.
You start having fewer colors available.  The same is true for multiply
lit (lighted?) objects where you do not need the range from black
to full on.  An example of low light situations would be used in 
night time flight simulators.

Toss in what is called Mach Banding, which is the eye enhancing contrast,
and there are people out there which can start to distinguish the difference
between green = 57 and green = 58 out of 256.

In conclusion, 24 bits is really nice, and I doubt that we will see anything
better (cost wise) in the near future, there are times when it is
not enough.  

enough spouting... :-)

brian moffet