[Scribus] Ligatures and "Expert Fonts" again

Andreas Vox avox
Thu Sep 22 15:34:06 CEST 2005

John Jordan wrote:

> > > And after the ligature issue is handled, could we have optical
> > > kerning? :)
> >
> > Scribus currently relies on the kerning information in the font. We
> > will add a manual kerning option soon. Adobe's optical kerning is
> > patented AFAIK (don't we hate those patent issues?). I don't know
> > about iKern (http://www.iginomarini.com/ikern.html).
> I'm not an expert on software patents, but I can't figure out how
> they could patent the concept. It's like Henry Ford being granted a
> patent for the idea of an "automobile," or WordPerfect Corporation
> being granted a patent for the concept of a word processor.

I got my impression from tphinney's comment from Thu, 2005-04-14 17:42
in this thread: http://www.typophile.com/node/10317
The way I read it Adobe used some German patent to implement optical 

There's some other comments on how optical kerning works in InDesign
(resp. does not work) you may want to read also.

> The way I understand optical kerning in InDesign is that it
> measures the area between the characters' outlines, using the
> baseline and x-height for the other dimensions (or perhaps other
> criteria as well for characters with ascenders and descenders), and
> then adjusts the kerning by thousandths of an em to make each
> character have the same area between it and the next character. I
> don't see how you could get a patent on the idea of measuring area.

Hm, I think there's more than one way to measure all that. iKern also 
takes into account some regularety about distances between stems etc. 
It's not only mathematics, you have to work against the optical tricks 
the human eye plays on us.

> Perhaps their patent is just on the code they wrote to accomplish
> this feat. If so, someone else could write different code that did the
> same thing.

I doubt that, see above.


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