Xref: utzoo comp.lang.postscript:5601 comp.sys.mac.system:883
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!axion!tsa!domo
From: domo@tsa.co.uk (Dominic Dunlop)
Newsgroups: comp.lang.postscript,comp.sys.mac.system
Subject: Re: PostScript vs TrueType?
Message-ID: <1990Jul26.135834.9874@tsa.co.uk>
Date: 26 Jul 90 13:58:34 GMT
References: <1100.26af57d3@waikato.ac.nz>
Reply-To: domo@tsa.co.uk (Dominic Dunlop)
Organization: The Standard Answer Ltd.
Lines: 46

[Loadsa postings on the net from NZ and Australia recently.  Hi folks.
What happened?  Anyways...]

In article <1100.26af57d3@waikato.ac.nz> ccc_ldo@waikato.ac.nz
(Lawrence D'Oliveiro, Waikato University) writes:
>The Spring 1990 issue of MacTech Quarterly had an interesting comparison
>of the relative virtues of the font handling schemes in PostScript versus
>Apple's TrueType system. 

>Anyway, one of the points of the article was that the hints in Adobe
>PostScript fonts merely identify important features of each character
>outline, and leave it to the interpreter (and imaging engine) to perform
>the appropriate transformations to preserve legibility at low
>resolutions. This is described as a "high level" approach, as
>opposed to the "assembly language" scheme of TrueType, which embeds
>explicit tweaking instructions in the outline description.

>Comments, anyone?

OK.  Why is a high-level approach almost always better than a low-level
approach?  Because a high-level approach can better accommodate new
technologies simply by labelling the low-level aspects of any technology,
whether new or old, as somebody else's problem.  Suppose I have one of HP's
spiffy new printers with Resolution Enhancement Technology.  The low-level
hints in a TrueType font are likely to be aimed at making ``dot/no dot''
decisions, and so cannot take advantage of an engine which can shrink dots
and slightly vary their horizontal placement.  High-level hints in
PostScript fonts leave details of implementation to the interpreter, and a
suitably clever interpreter (if Adobe or a clone maker should come up with
one -- and that's quite a big if) could correctly drive RET, and so produce
slightly better-looking results than TrueType.  I'd guess that similar
considerations would apply to anti-aliasing of character edges on grey-
scale monitors by using shades of grey rather than straight black-white
transitions.  A PostScript RIP behind the screen should (assuming enough
MIPs and memory to cook up fonts at a bearable speed) be able to do this.
Would TrueType?

Possibly talk of MIPs hints (pun intended) at Apple's and Microsoft's
reason for going low-level.  Most of the installed base of Macs and PCs has
little power to spare for working out how to respond to a hint: better and
cheaper to tell the poor little machine exactly what to do -- even at the
cost of future problems or sub-optimal performance.

Course, I could be wrong.  TrueType hints may do all this.  Comments anyone?
-- 
Dominic Dunlop