Hi everyone,
I recently got a new Macbook Pro, which I dual-booted into Ubuntu 13.10
(Linux kernel 3.11). My previous computers were from 2008 and used ATI
or Nvidia graphics cards. The new one (with Intel HD 4000 integrated
graphics, core i7, no other graphics card) seems to cause me a lot of
eyestrain compared to what I'm used to. The experience I have is that
light surfaces appear to shimmer in a way that didn't used to happen,
and this shimmering seems to be related to the eyestrain. After about
an hour I really don't want to use the computer anymore; it's like a
burning/sore feeling in the eyes coupled with dry eyes. It's not a
monitor problem, because I can hook up the Macbook to an old monitor
which works perfectly well with old hardware (no eyestrain) and the
eyestrain is still there. So it would appear to be due to the graphics
hardware/driver combination. It's also not Intel-specific or
OS-specific; I've seen the same effect on Mac OS X and using different
video cards; it seems to be the new normal. I'm really confused about
what could be causing this. Resolutions don't matter; you always get
the eyestrain. My first thought was temporal dithering (or
spatiotemporal dithering), but my reading of the intel driver source is
that the kernel drivers have disabled ST dithering in favor of spatial
dithering. I have seen a few people report similar problems in mailing
lists (including this one), and some of them got some relief by
disabling the DRI/DRI2 extension in Xorg (this was around 2010), which
doesn't seem to do much for me (nor does switching to the modesetting
driver or fbdev driver). (Interestingly, using modesetting/fbdev drivers
doesn't seem to slow down glxgears either, which always claims to run
around 1700 FPS). Some people got relief by switching to the Vesa
driver, which my Xorg won't accept; it just unloads it and reloads the
Intel driver. Interestingly, the eyestrain is present even before X
loads up or if you don't load X at all; when the system boots you can
see very flat-looking text (which I think is OK) and then it switches to
a more shimmering kind of text (presumably when the intel driver kicks
in). You would think plain text would have absolutely constant pixel
values, but that isn't what I see (except on old hardware).
I'm sure that 99% of people can't notice this, but for the 1% who can
it's a huge pain. I'm on another mailing list with dozens of other
people with similar problems, so it isn't just me. If anyone has any
suggestions as to what I/we can try (not eyedrops, I mean software
stuff) or where I can look, I'd be really grateful. I've had my eyes
checked recently and they're fine.
Thanks!
Mike
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