Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!rex!ames!oliveb!apple!turk
From: turk@Apple.COM (Ken "Turk" Turkowski)
Newsgroups: comp.graphics
Subject: Re: 8bit -> 5bit / pixel reduction
Message-ID: <1437@internal.Apple.COM>
Date: 19 Apr 89 12:03:23 GMT
References: <YYGUd-y00XomA4BkVj@andrew.cmu.edu>
Organization: Advanced Technology Graphics, Apple Computer, Cupertino, CA, USA
Lines: 20

In article <YYGUd-y00XomA4BkVj@andrew.cmu.edu> ks26+@andrew.cmu.edu (Kenneth Sykes) writes:
>This may be a stupid question but...
>
>When converting 8bit/pixel color to 5bit/pixel color, are any side effects
>introduced if the top 5 bits are used (c >> 3)?  How about converting the
>other way, say 3bit/pixel -> 5bit/pixel?  Are there more efficient ways
>of doing this?

You mean, artifacts besides quantization?

The maximum for 5 bit pixels is 31, for 3, 7, therefore:

	five = three * (31/7);

You can be more efficient if you use shifts and adds.
-- 
Ken Turkowski @ Apple Computer, Inc., Cupertino, CA
Internet: turk@apple.com
Applelink: TURKOWSKI1
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