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Re: [Freetype] any plan on "ClearType"

From: David Turner
Subject: Re: [Freetype] any plan on "ClearType"
Date: Mon, 09 Sep 2002 23:40:39 +0200
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.0) Gecko/20020530

Changyuan Hu wrote:
Hi, my dear FreeType developers,

It would be nice to see FreeType project include special rendering tool for LCD 
displays using the horizontal subpixel rendering technology, as is used in 
Microsoft ClearType. I thought it might be a problem with intellectual property 
until I found the following site:

The author of this site said that Apple II graphics programmers were already using the 
vertical subpixel rendering 22 years ago. Much different from what Microsoft stated as 
something "unprecedented innovation".

If so, FreeType developers will have the freedom to developer this technology 
and I am sure lots of LCD software developers will benifit from your great work.

It's already possible to implement this on top of FreeType (e.g. libXft does 
it, but
don't ask me how to configure your system to use it ;-). I have recently added
LCD-optimized hinting _and_ rendering to the library but this is still

In all cases, generating LCD-optimized glyph images is one thing. Composing them
on colored bitmaps is however a special operation that very few graphics library
support (most of them support transparent blitting where the same alpha 
is used for all R/G/B components. For ClearType-like rendering, each channel has
its own translucency/alpha value..)

But indeed, the reasons why I'm moving this code within the library are:

  - it's possible to perform device-specific hinting for
    RGB/BGR LCD screens

  - it allows things like Qtopia, GDK-Embedded, etc.. to use the
    technology more easily

  - it's just fun :-)


- David Turner
- The FreeType Project  (


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