[luatex] the hz algorithm (was:Re: LuaTeX file almost 2.5x bigger)

Reinhard Kotucha reinhard.kotucha at web.de
Sun Aug 8 23:22:45 CEST 2010

On 8 August 2010 Pablo Rodríguez wrote:

 > On 08/08/2010 02:21 AM, Reinhard Kotucha wrote:
 > > On 7 August 2010 Martin Schröder wrote:
 > >
 > >   >  2010/8/7 Pablo Rodríguez<oinos at web.de>:
 > >   >  >  I guess there is no way to avoid it (since there is no easy way
 > >   >  >  to avoid the patent itself).
 > >   >
 > >   >  Well, the patent is EP0466953, which should have expired on
 > >   >  2010-07-18 (1990-07-17 plus 20 years), but IANAL... :-)
 > >
 > > There are also severe technical problems.  I assume that Zapf's idea
 > > is based on multiple-master fonts.  But since such fonts are not
 > > available, there is no easy way to implement Zapf's algorithm.
 > > Hence it's not only a legal problem.
 > Thanks for your reply, Reinhard.
 > I'm not a lawyer, but even in the legal side of this issue (when the the 
 > European doesn't expire until 1/1/2011), there might be a related patent 
 > for a line-breaking algorithm granted to Adobe 
 > (http://www.freepatentsonline.com/6510441.pdf) that might involve the 
 > hz-algorithm (http://typophile.com/node/16525).

The patent only mentions an article written by Zapf and Karow in
section "OTHER PUBLICATIONS".  I do not see anything about character
protrusion or font expansion in the patent itself.
 > > The difference between Thanh's and Zapf's algorithms is that Thanh
 > > scales the glyphs horizontally while Zapf proposes to create dedicated
 > > instances of a font where the stroke width is preserved.
 > >
 > > Quite strange: There is no easy way to implement Zapf's algorithm
 > > anymore since we have/prefer Type1 fonts, TTF, and OTF.  With
 > > Metafont, I believe, it's not a big deal. :)
 > If I don't get you point wrong, the original hz-algorithm is not 
 > suitable for other fonts than Multiple Master, is it?

Yes.  If the stroke width has to be preserved, you can't simply scale
the glyphs horizontically.  An example is here, see the figure showing
the letters "m" and "i":


It seems that the implementation of font expansion in InDesign is
quite similar as in pdfTeX.

 > I wounder whether US Patent 6510441 
 > (http://www.freepatentsonline.com/6510441.pdf) solves this.

No, it's only about line breaking.  See my response to Martin's mail.


Reinhard Kotucha			              Phone: +49-511-3373112
Marschnerstr. 25
D-30167 Hannover	                      mailto:reinhard.kotucha at web.de
Microsoft isn't the answer. Microsoft is the question, and the answer is NO.

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