[Trisquel-devel] Would enabling bytecode interpreter in Freetype cause patents problems or break in some way Trisquel policies?

[Flop Flop]

Just some further observations on font rendering in Ubuntu/Trisquel:

I found some posts in Ubuntu forums about this issue (they go back to 2005-6, I think, so the situation might have changed afterwards as you say) which seems to point that subpixel hinting was achieved in Ubuntu through the "auto-hinting" process of Freetype and not by the bytecode interpreter. I went to the links which I provided in my previous post to check the explanation about the subpixel hinting process (I think it was this particular process the one which was affected by patents, using freetype what was called "auto-hinting" in order to circumvent patent problems) and there has been a change in the situation in this fairly short time. This is what its author explains (http://freetype.org/patents.html):

1) "Since May 2010, all patents related to bytecode hinting have
      expired worldwide.  It is thus no longer necessary to disable the
      bytecode interpreter, and starting with FreeType version 2.4, it is
      enabled by default."

2) "The colour filtering algorithm of Microsoft's ClearType technology
      for subpixel rendering is covered by patents.  Note that subpixel
      rendering per se is prior art; using a different colour filter thus
      circumvents Microsoft's patent claims."

I have not been using MS Windows for quite a long time -barely ever used Vista or later versions- but I think that "Cleartype" technology in XP provided a crisper text than (even) current Ubuntu/Trisquel versions, particularly, as I said, on lower resolution monitors (e.g. 1024x768). Besides, enabling full subpixel hinting (both on Gnome and KDE) does not produce, I think, a perfect result (i.e. a crisp text, particularly on smaller characters). While web browsers seem to render better small characters, in Open Office in particular it modifies (in a negative way, IMO) character spacing and also modifies the shape of characters. 

Provided that Ubuntu/Trisquel are alredy using bytecode interpreter, might these differences in font rendering between MS Windows and Ubuntu/Trisquel be due to using a different colour filter -as pointed out in 2) above by Freetype author-? Would it be possible to tweak that colour filter in some way to achieve that crisper text provided by Cleartype? A last question, Trisquel 3.5 is using libfreetype 2.3.9, would 4.0 be using libfreetype 2.4 -perhaps that version makes a difference-.

Thanks.


--- El sáb, 24/7/10, Rubén Rodríguez Pérez <ruben en trisquel.info> escribió:

De: Rubén Rodríguez Pérez <ruben en trisquel.info>
Asunto: Re: [Trisquel-devel] Would enabling bytecode interpreter in Freetype cause patents problems or break in some way Trisquel policies?
Para: trisquel-devel en listas.trisquel.info
Fecha: sábado, 24 de julio, 2010 10:45


> I enclose here a copy of a question posted in the forum sometime ago
> concerning Freetype in which I am particularly interested -it was
> posted under a different issue, so just in case it went unnoticed-. I
> have read about Apple/Microsoft patents which prevent Freetype from
> using the "bytecode interpreter" in order to render truetype fonts.

AFAIK Ubuntu's freetype package (and hence Trisquel's) already has the
bytecode interpreter enabled by default.
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