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From: laser-lovers@uw-beaver
Newsgroups: fa.laser-lovers
Subject: Re: PostScript printers vs. ImPress printers
Message-ID: <589@uw-beaver>
Date: Sat, 26-Jan-85 01:51:02 EST
Article-I.D.: uw-beave.589
Posted: Sat Jan 26 01:51:02 1985
Date-Received: Mon, 28-Jan-85 07:37:04 EST
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Organization: U of Washington Computer Science
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From: Brian Reid <reid@Glacier>

    Perhaps I am confused, but Brian seems to be saying that
    PostScipt uses a size-independent outline description for a
    character in a particular font, and can arbitrarily rotate it
    before conversion to a bitmap.
Nope, that is what I am saying. You are not confused.

    I was under the impression that there was no such
    size-independent representation.  Isn't that what the whole
    hoopla over bit-tuning is all about?  Certainly MetaFont is
    incapable of producing a uniformly great font at 300 dpi
    resolution, 10 point.

It may or may not be impossible, but the PostScript printers do it and
do it well. If you want to see an example, look at the recent POPL
conference publicity. The flyer announcing the conference announcement
was set with Scribe on an Apple LaserWriter in 8-point Times Roman
using a font described with ordinary outlines. One of the recent issues
of CACM (I think it was the November issue) had a 2-page advertisement
for the POPL conference somewhere towards the back. That advertisement
was also set on an Apple LaserWriter in PostScript. It isn't quite so
remarkable because it uses 10-point letters and does not use any
rotated fonts or graphics, but it is an example of the PostScript
raster conversion. Remember that it has been through a printing press.

I have carefully avoided learning anything about how the internals of
the PostScript font mechanism work, because I often have difficulty
keeping my mouth shut and I don't want to give away any Adobe secrets.
But you may rest assured that an ENORMOUS amount of software cleverness
and expertise in the nature of laser printers has gone into the
PostScript system. I think that I will have to doublecheck back with
the folks at Adobe to find out what I am allowed to say and what I am
not allowed to say before I give you any more information about the
font representation, but please understand, for the moment, that the
fonts are indeed represented as size-independent outlines and that they
can be artitrarily scaled and rotated before being scan-converted and
that the scan-conversion works just fine in point sizes down to 4 on a
300dpi printer.

Brian