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

King InuYasha ngompa13 at gmail.com
Sun Mar 22 22:28:46 UTC 2009


On Sun, Mar 22, 2009 at 5:18 PM, Jud Craft <craftjml at gmail.com> wrote:

> Hello there, thanks for reading.  This may be a bad place for this
> post, I apologize if so.
>
> Here's the problem, stated over and over throughout bad forum posts:
> subpixel-rendering on Fedora is a little sub-par.  The chief reason
> (from my lay perspective) is that it doesn't implement the various
> cleartype-like filtering algorithms demonstrated in all sorts of
> questionable patches, due to fear of patent-infringing on Microsoft's
> Cleartype work.  This means Fedora's default subpixel-rendering is
> full of color-fringes and in general less smooth than other algorithms
> shown in (for example) Debian and Ubuntu.
>
> Currently the only solutions are:
>
> 1.  Try out freetype-freeworld:  restores the bytecode interpreter to
> Freetype and some adds filtering, patent-infringing, stuck in
> RPMFusion, can't be merged into Fedora.
> 2.  Try out those peculiar cleartype-patches flying around the forums:
>  you get all filtering functionality back, but again, patent
> infringement.
>
> Okay, here's something different.  Check this out:  Qt (that other GUI
> toolkit) actually developed their own method to reduce the color
> fringing on subpixel-rendering:
> http://labs.trolltech.com/blogs/2008/09/01/subpixel-antialiasing-on-x11/
>
> Qt is not perfect (their filter automatically locks you into
> full-hinting on Qt 4.4, but that'll be fixed in 4.5), but their method
> (without using any other patent-infringing algorithms) is very
> beneficial.  You'll note their un-filtered examples look just as bad
> as the current filtering in GTK in Fedora, while their fixed-examples
> look pretty decent.
>
> So here's the idea:  perhaps Fedora could petition Pango (I think
> that's the system GTK uses to render glyphs) to include the
> Qt-filtering style in their own upstream code.  This would mean that
> both GUI toolkits on the Linux desktop would then have patent-free,
> non-color-fringing, subpixel rendering by default.
>
> And today currently, keep in mind that Qt on Fedora already has this
> new filtering, so I don't think there are any patent-problems with it:
>  Qt's solution seems to be a simple blur of their own ingenuity, and
> nothing related to Cleartype.  (Otherwise Fedora wouldn't ship it, I'd
> assume).
>
> --
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> https://www.redhat.com/mailman/listinfo/fedora-devel-list
>

A good idea yes, but the reason why Fedora and other USA-based distros have
such bad font rendering is because the hinting algorithms in freetype are
patented not by Microsoft, but by Apple.
http://freetype.sourceforge.net/patents.html

Meh, ClearType is just the same as the subpixel hinting that is patented by
Apple, just a different name.
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