Re: IDS rendering and IDS analysis (was RE: Problems/Issues with

From: Jungshik Shin (
Date: Tue Apr 11 2000 - 17:21:46 EDT

On Mon, 10 Apr 2000, John Jenkins wrote:

> on 4/10/00 6:12 AM, at
> wrote:
> > However, the 3.0 book and other sources now timidly mention "IDS rendering".
> > This means that an Unicode display engine has the faculty (but *not* the
> > obligation!) to generate a glyph on-the-fly, and display it in place of the
> > IDS itself.
> >
> No current Unicode display engine has the faculty to generate a glyph
> on-the-fly. Some have the ability to substitute single glyphs for an entire
> IDS if such is known in advance by a font designer.

  Hmm, I thought ATSUI(?) of MacOS has something similar for Thai,
Indic scritps and even for Hangul. That is, complex
context-sensitive(pre-defined fixed) m to n mapping of characters to
glyph indices. By the way, even a very primitive X11 rendering engine
of bitmap fonts can emulate 'the effect'(generating glyphs on-the-fly)
fed by justaposing a set of zero-width/negative-width(non-advancing)
glyphs and final advancing glyph.

> > This naturally leads to Jon's thought: what if IDS, or a similar mechanism,
> > is generalized to all CJK characters? Wouldn't it be possible to encode any
> > CJK text with only a handful of combining logical units? Or, alternatively,
> > wouldn't it be possible to design "light" CJK fonts, containing only glyphs
> > for the basic graphic units?
> >
> Theoretically, this is true. In practice, it is not. There are enormous
> problems of graphic variation, ambiguity in the breakdown, and breakdown
> into non meaningful pieces. Think of trying to describe Latin text using a
> handful of curves and straight lines with appropriate connectors.

   I wouldn't say for sure it's possible for Chinese ideographs
in practice(although it's a very interesting idea. I've seen Jon
advocating this a few years back on the list and I also saw a web page
describing this somewhere at Stanford CS dept web site) , but it should be
certainly possible for Korean Hangul(as we have done in many occasions).

   Jungshik Shin

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