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From: bobr@zeus.UUCP
Newsgroups: comp.graphics
Subject: Re: effective resolution and anti-aliasing
Message-ID: <1818@zeus.TEK.COM>
Date: Tue, 9-Jun-87 16:14:40 EDT
Article-I.D.: zeus.1818
Posted: Tue Jun  9 16:14:40 1987
Date-Received: Sat, 13-Jun-87 01:52:56 EDT
References: <1713@ames.UUCP>
Reply-To: bobr@zeus.UUCP (Robert Reed)
Organization: CAE Systems Division, Tektronix Inc., Beaverton OR
Lines: 13

If you've seen anything in those textbooks about anti-aliasing, then you've
seen the methods used to perform this miracle of modern technology.
Aliasing is the effect of producing false images by undersampling source
images with higher spacial frequency than the display.  A line of less than
one pixel width exhibits this higher than displayable spacial frequency.
The techniques of anti-aliasing sample the image at a high enough frequency
to capture such details and then averages those samples in such a way that
some representation remains when actually displayed.  The general effect is
one of blurring the details.  Thus the less-than-a-pixel-wide line becomes a
softened image that may still look like a line.

-- 
Robert Reed, Tektronix CAE Systems Division, bobr@zeus.TEK