[cairo-bugs] [Bug 16216] Fill don't work properly

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Tue Jun 3 12:36:53 PDT 2008


--- Comment #6 from Behdad Esfahbod <freedesktop at behdad.org>  2008-06-03 12:36:51 PST ---
Created an attachment (id=16894)
 --> (http://bugs.freedesktop.org/attachment.cgi?id=16894)
photo of lcd rendering

I took two macro photos of your screenshot on my lcd, at about 17000dpi
(resized down to about 4500dpi in the attached image).

The left side shows the left border of the ellipse, with a blue pixel to the
left of the red pixel.  The subpixels are "rgBRgb" with capital letters being
on and small off.  So, the blue and red regions touch perfectly.

The right side of the image shows the right border of the ellipse, with a red
pixel to the left of a blue pixel.  Here the subpixels are "RgbrgB".  You can
see that there are 4 off subpixels between the red and blue regions, showing a
visible wider-than-pixel black gap.

To "fix" this we need to go as far as doing subpixel rendering of all the
graphics.  Nothing impossible, but low prio and not on the horizon right now. 
(the correct rendering will offset all the graphics by 1/3 pixel and render
again, for each color component...)

The fact that you use CRT doesn't make much difference.  I know because I have
photographed CRTs recently too, and the subpixel structure of all modern (say,
last fifteen years) CRTs is the same as modern LCDs.

Hope that helps.

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