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From: crm@romeo.cs.duke.edu (Charlie Martin)
Newsgroups: comp.graphics,comp.text
Subject: Re: Gray-scale antialiasing (yes, it can work)
Summary: Is this fine a positioning error perceptible?  I think not.
Keywords: grayscale fonts
Message-ID: <12887@duke.cs.duke.edu>
Date: 19 Nov 88 16:37:11 GMT
References: <74013@sun.uucp> <148@internal.Apple.COM> <4763@mnetor.UUCP> <8811112202.AA21230@explorer.dgp.toronto.edu>
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In article <8811112202.AA21230@explorer.dgp.toronto.edu>, avi@dgp.toronto.edu (Avi Naiman) writes:
> Not necessarily.  Although previewing a typeset document is a good example,
> I see the trend in windowing systems heading towards more 'ergonomic'
> presentation of textual material.  This has been amply demonstrated in
> 'research' prototype user interfaces which use proporational spacing,
> a variety of fonts and size, and context-sensitive typography.  These advances
> are beneficial for editing, scanning, and reading all types of documents
> (including programs).

I'm only peripherally (heh, heh) interested in text presentation, so I
haven't been keeping up with the appropriate cog and perceptual psych
literature, but it seems unlikely that sub-pixel positioning makes a
whole hell of a lot of difference to perceived text quality.  Current
grey-scaling monitors I've dealt with have a resolution in the
neighborhood of 90 d.p.i.  If we have the appropriate hardware to do
anti-aliasing based on some absolute position that's "continuous" --- a
much finer positioning than the discrete 90 positions --- and mapped to
the monitor using greyscale, the maximum error in position is still
only 1 / 180 inches.  Since this is less than 1/2 a printer's point, I
have to *strongly* question whether this error is significant in
typeset text --- because *nobody* adjusts to 1/2 a point, even in good
old Benj.  Franklin cold type --- and in fact, I question whether it is
perceptible at all.
Charlie Martin (crm@cs.duke.edu,mcnc!duke!crm)