[OLPC-devel] Emulating the laptop display with Xephyr

Mark J. Foster mfoster at laptop.org
Sat Jul 29 09:08:56 EDT 2006


Hi, Manu!

Nice description!  I'm sorry that I didn't see your (better) response 
before I posted one myself - my apologies!

Cheers!
MarkF

Manu Cornet wrote:
> Hi !
>
>> Is the text antialiasing algorithm sub-pixel based, or does it
>> assume non-swizzled pixels?
>
> Basically, the antialiasing algorithm works as follows:
>
> * For each pixel, first figure out which color it will be when
> swizzled (e.g., red). Then sum up the corresponding color component
> (e.g., red) from its four neighbors (up, down, left, right). At this
> point the image hasn't been swizzled yet.
>
> * Add one eighth of this sum to one half of the current pixel's
> corresponding color value (e.g. red): that's the final value of the
> pixel.
>
> * Proceed with color swizzling.
>
> That's about it :o) With this process, information that would be lost
> while just swizzling (e.g., discarding the blue signal in a green
> pixel) is spread around to the neighbors.
>
> Cheers,
> Manu
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