[cairo] Subpixel Positioning w/FreeType

Freddie Witherden freddie at witherden.org
Thu Oct 8 01:24:48 PDT 2009

On Thursday 08 October 2009 01:13:28 Bill Spitzak wrote:
> The 4 bits may only be some internal data storage and ClearType may be
> using fewer images, ie some of the 16 possible sub-positions map to the
> same glyph. 4 is the smallest power of 2 that will give 3 positions
> anything close to equal weight and may explain why it was chosen.

It is my understanding that three positions of subpixel precision were chosen 
as most LCD screens are made up of three vertical subpixels. While it does 
seem theoretically possible to have more than that by adjusting the intensity 
of the pixels this is likely to cause blur glyphs further.

Regards, Freddie.

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