A supposedly patent-free suggestion/solution to the curious subpixel rendering in Fedora

[Behdad Esfahbod]

On 03/27/2009 03:34 PM, Jud Craft wrote:
> Sir, the subject is not false.  You may be a text-stack-maintainer,
> but I am not a moron.

Then please point it out to me where the "supposedly patent-free" claim come from.

[...]
> They obviously have developed their own filter code (see above),
> sometime before Freetype removed their own built-in LCD-specific
> filtering.  The final result is apparently comparable to Freetype's
> old (patent-infringing) filters.

Sure, Qt developed their own.  Xft and cairo also developed their own (written 
by Keith Packard).  Then FreeType developed four, one of which similar to the 
one in Qt, Xft, and cairo (developed by David Turner).
Your reasoning seems to be:

   - The filter in Xft and cairo is patent-infringing
   - The Qt filter was developed separately
   = Result: The Qt filter is supposedly patent-free

That's baseless.  That's deducing ~p=>~q when we know p=>q.

Anyway, to make it clear, the reason the filter in Xft and cairo is 
patent-infringing is not because someone copied it from ClearType.  No.  It's 
infringing because the whole idea of subpixel filtered text rendering is 
patented.  You can implement and reimplement and reimplement.  Doesn't make a 
difference (until the patents expire).


I'm sure you didn't mean to waste anyone's time.  It just looked more like 
what one typically finds on news sites: an eye-grabbing title with no support. 
  Thanks for clarifying.

behdad