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From: raveling@vaxb.isi.edu (Paul Raveling)
Newsgroups: comp.graphics,comp.text
Subject: Re: Gray-scale antialiasing (yes, it can work)
Keywords: grayscale fonts
Message-ID: <6750@venera.isi.edu>
Date: 10 Nov 88 18:01:02 GMT
References: <74013@sun.uucp> <148@internal.Apple.COM> <4763@mnetor.UUCP> <174@internal.Apple.COM> <19809@apple.Apple.COM> <8811080140.AA15368@explorer.dgp.toronto.edu>
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Reply-To: raveling@vaxb.isi.edu (Paul Raveling)
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In article <8811080140.AA15368@explorer.dgp.toronto.edu> avi@dgp.toronto.edu (Avi Naiman) writes:
>
>>From my experience, I find it hard to believe that one can today
>compare a screen font (regardless of whether or not there is grayscale)
>with an *equivalent* hardcopy sample.  ...

	Human perception makes it even harder to do an objective
	comparison.  Particularly in fonts, humans often see things
	their mind has been trained to see based on fragmentary cues.

	The example I sometimes show is a 512x464 map image, digitized
	from a printed map, with the words "INDIAN OCEAN" printed
	in a clean-looking roman font.  However, positioning a
	magnifier window over one of the N's show not only that
	the character is a ragged-looking array of pixels, but also
	that the vertical bars of the N don't exist at all!

	As a further exercise, positioning something such as a cursor
	over the serif at the end of a vertical bar causes the verticals
	to disappear, as observers see it.  What people perceive
	normally is a fine line, less than 1 pixel wide, that doesn't
	actually exist.  That perception is triggered by the pattern
	of serifs and the bold diagonal.  Even perception of those parts
	of the letter that DO exist is cleaned up substantially
	by the observer's mind.


	While idiosynchrasies of perception make it harder to do unbiased
	evaluation of fonts, it may also be possible to employ them
	to advantage.


---------------------
Paul Raveling
Raveling@vaxb.isi.edu