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From: zerkle@iris.ucdavis.edu (Dan Zerkle)
Newsgroups: comp.sys.amiga.misc
Subject: 24bit vs 32bit color (Re: Mac can emulate amiga&has over 1,000,000 colors)
Message-ID: <8714@ucdavis.ucdavis.edu>
Date: 5 Apr 91 23:35:30 GMT
Article-I.D.: ucdavis.8714
References: <49174@nigel.ee.udel.edu> <1991Apr1.185501.6295@ccu.umanitoba.ca> <+0#ghwl@rpi.edu>
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Reply-To: zerkle@iris.ucdavis.edu (Dan Zerkle)
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In article <+0#ghwl@rpi.edu> metahawk@itsgw.rpi.edu (Wayne G Rigby) writes:
>32 bit color graphics is effectively the same as 24 bit graphics.  There
>are only 2^24 (16,777,216) colors on screen.  The extra 8 bits (alpha control)
>are (from what I've heard) used for transparent objects and perhaps color
>cyling, among other things that I have no idea about.

Not necessarily.  In some cases, you want to use the extra 8 bits for
the alpha channel, usually to indicate transparency.

However, some devices can use all 32 bits for color:

10 bits of blue
11 bits of red
11 bits of green

The justification for this is that people can distinguish fewer shades
of blue than other colors.

Although under most conditions, the human eye can not tell the
difference between two 24 bit colors next to each other, it apparently
can happen under certain circumstances, resulting in (so-called) "mach
banding".  Real, live, 32 but color can eliminate this completely.

IMHO, though, you're not bloody likely to need this.  24-bit gives you
more colors than humans can distinguish.

           Dan Zerkle  zerkle@iris.eecs.ucdavis.edu  (916) 754-0240
           Amiga...  Because life is too short for boring computers.