Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!udel!rochester!ken
From: ken@cs.rochester.edu (Ken Yap)
Newsgroups: comp.fonts
Subject: Re: Universal font standard
Message-ID: <8620@sol.ARPA>
Date: 14 Apr 88 00:54:23 GMT
References: <3178@gryphon.CTS.COM> <219@ateng.UUCP> <7645@brl-smoke.ARPA> <701@sun.soe.clarkson.edu> <952@ima.ISC.COM>
Reply-To: ken@cs.rochester.edu (Ken Yap)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 37

|As Dr Peter Karow points out in "Digital Formats for Typefaces"
|URW Verlag 1987 ISBN 3-926515-01-5 (this is the English Version)
|
|	(p. 106)
|	Inherent in the hierarchy, and fundamental in the URW
|	philosophy, is that the IK format has a digital precision which
|	is greater than that required by the typesetting machine.
|	Letters in IK format are stored in a raster of 15,000 x 15,000
|	per em.  This has the advantage that when preparing coarser
|	rasters there is no interference between the stored raster and
|	the target raster.
|
|He goes on to explain that at 400 rasters/em, which he considers the
|current average for good typesetting machines, the samples would be
|every 37.5 lines, which is sufficient, whereas if you were sampling
|from an 800 rasters/em master, there would be major problems in
|generating a smooth image at both 400 and 401 rasters/em (for
|instance).

Perhaps I misinterpreted Karlow, but I understood this 15,000 line per
em raster to be conceptual or at least a transient product during the
generation of a lower resolution raster. As the appendix indicates,
there is a semi-hierarchy of storage formats. My interpretation is that
Ikarus stores glyphs as outlines primarily and the resolution of the
coordinate system is 15k per em.

An interesting fact is that Ikarus fonts are digitized by hand from
large masters. Karlow talks about photographic techniques and asserts
that they found hand digitizing superior. This after years of trial.
At first they couldn't believe that simple was best.  Karlow claims
that some "respectable" foundries have marketed typefaces with noise
from ink smudges in the photo masters!

To be fair, there is a lot more to it than just running out and buying
a tablet and crosshair. It's all in the book. Recommended.

	Ken