Xft Hack Improves Antialiased Font Rendering

Eugenia writes: "Font antialiasing first made its way to XFree through Qt/KDE only a year ago and GTK+/Gnome followed some time after. Even with the latest version of Freetype 2.08, which reportedly brings better quality, the result is still not up to par with the rendering quality found on some commercial OSes. David Chester has hacked through the Xft library and he achieved an incredibly good quality on antialias rendering under XFree86. With this hack, at last, XFree can deliver similar aesthetic results to Mac OS X's or Windows' rendering engines. Check the two brand-new screenshots ('before' and 'after') at his web page and notice the difference with your own eyes."

Comments

good, but not quite excellent..

[thesupraman]

Having worked with GOOD font rendering software (mainly for broadcast television) I can say that most gui renderers do a pretty horrible job.

It's not that they get the font shape wrong, or don't antialias correctly, it's that they don't allow for how people see things, and just antialias 'mathmatically correct'.

With the fonts we use for television character generaters, several seperate rendering passes are used to give:
1 - a solid and anti-aliased 'interior' to the font (this is 'normal' antialiasing)
2 - a perimeter or border to the font, in a slightly different colour/darkless level, to make the edge stand out
3 - a seperate rednering to the alpha channel to stop the font from 'blending' excessivly at the edges with the background (ie: a buffer zone).

This makes a MASSIVE difference to the quality of the fonts, especially on anything other than a solid colour background.

unfortunately, no OS as yet does this for it's screen display fonts, which is a pity, as it makes a BIG difference.

Having said that, I'm VERY happy that improvements are happening, as good font rendering makes a hugh difference to the effort required to read text.

Re:good, but not quite excellent..

[thesupraman]

Hmm, I guess we don't do real time text then, damn, I was pretty sure that was what I did, certainly looks like it, I must have been dreaming...

Of course, there IS a difference when you need to display a full page of scrolling text at speed, but since characters are normally only rendered once each, and then cached, the processor time required to do high quality anti-aliased text is actually very very small in relation to just about everything else (laying out the text is a much more processor intensive task for most uses).

The time required to properly alpha-blend it is a little higher (depending on the windowing system and graphics hardware), but still not that great.

One BIG thing that gets missed is the fact that antialiasing for LCD is quite different from antialiasing for trinitron, which is quite different for antialiasing for a standard CRT, due to dot placement/shape, and that also makes quite a difference (I believe microsoft has an LCD mode, and freetype can do one, from memory).

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[account_deleted]

Comment removed based on user account deletion

Re:ClearType?

[taion]

XFree86 4 supports sub-pixel anti-aliasing (aka ClearType). You just need to put match edit rgba=rgb; in XftConfig.

Greetings.

[Anonymous Coward]

Here's another mirror. Sorry about those stupid ads.

I also want emphasize one thing that I say on the website. I can't take a whole lot of credit for the improvement. For sure, the freetype project and Keith Packard, author of XRender and Xft did all of the hard work. I just tweaked a few settings (adjusted glyph proportions and turned off hinting).

David Chester