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Old 09-19-2012, 03:16 PM
Camaleón
 
Default Display hurtful on LCD screen with Wheezy

On Tue, 18 Sep 2012 23:31:21 +0200, Lionel Trésaugues wrote:

> I am experiencing a physical pain whenever I am in front of my computer
> running either Debian (Wheezy) or Debian-based distributions (such as
> Mint LMDE, XFCE or MATE edition). Switching from XFCE to MATE doesn't
> lead to any improvements .
>
> My eyes start to suffer and soon, I can feel that an headache is coming.

(...)

> Could you help me to solve this problem ?

Yes, but better if you describe in detail what kind of pain you are
feeling because how the screen has to look like can be sometimes a matter
of personal preference :-)

> Here are the specifications of my system :
>
> Computer : Acer Aspire 6930G
> Graphic card : GeForce 9600M GS (with the proprietary Nvidia drivers
> (version 302.17) enabled)
>
> My xorg.conf :

(...)

No "xorg.conf" file should be needed but in the event you want to use
it, better with the bare minium data configuration on it.

> The output from xrandr (when the VGA secondary display is disconnected):
>
> Screen 0: minimum 8 x 8, current 1366 x 768, maximum 8192 x 8192
> VGA-0 disconnected (normal left inverted right x axis y axis)
> LVDS-0 connected 1366x768+0+0 (normal left inverted right x axis y axis) 353mm x 198mm
> 1366x768 60.0*+
> HDMI-0 disconnected (normal left inverted right x axis y axis)

Mmmm... At a first glance I see nothing wrong from the xrandr output,
I mean, technically speaking both resolution and refresh rate values
are right.

Greetings,

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Old 09-19-2012, 09:40 PM
Lionel Trésaugues
 
Default Display hurtful on LCD screen with Wheezy

First, thanks all of you to try to solve the issue I encounter with Debian.

I will come back now to some of the points you mentioned in the discussion.


How important is it to you to be able to run Debian? Would it be
worth some spectacles, or some new ones if you already wear them?
(This solution worked for me.)

Have you tried any of the rpm distros?


I can live with other distributions than Debian, but I would like to use it as a
base to setup a very lightweight working environment.
I found that the Ubuntu distribution contain a lot of extra-tools that I would
not need, and their use in cpu resources is slightly higher than pure Debian (on
the same hardware).
No spectacles for me. I don't think I need some, because everything is very fine
whenever I am running Ubuntu-based distributions and I am able to work for hours
in front of the screen without feeling any disturbance.


I haven't checked what is the outcome with rpm distros, but plan to have a look
soon on Fedora to check how it goes.



Incidentally, do you know what changed immediately before this
started to happen?


Nothing has really changed. This phenomenon appeared as soon as I started to
boot into fresh Debian installation.



A minimum refresh rate of 72Hz is recommended (same as average human
heart rate) to minimize optical discomfort that you seem to be
suffering. Less than that the screen will often jump about and make
it difficult to see properly. See if you can do something about that.

I am running Ubuntu-based distro at 60Hz (on the same hardware) without
experiencing this problem.



Try adjusting the brightness and contrast (of the display itself).


Lowering the brightness helps a little bit to make the pain more bearable, but
it is still unpleasant and hurtful after a while.



Do the fonts look different in Debian? If so, in which way? If
they do, you could try to find out how they are rendered and try to
have them rendered the same in Debian.


The fonts (with the same hinting and antialiasing settings) look very slightly
blurrier on Debian than on Ubuntu. I heard about the libcairo package difference
between Ubuntu and Debian, but I am not sure this is still relevant. I guess
some improvements have been pulled to the Debian libcairo package to make the
fonts look almost as nice as they are in Ubuntu.



You can try the following in ~/.fonts.conf.d --- I wasn't happy with
how the fonts were rendered and I like them better with these
settings:


I tried to use any kind of settings (playing with the "Appearance" menu of the
desktop environment, adjusting the different parameters through
fontconfig-config and add these paramaters in /etc/fonts/local.conf) with
visible results (the shape of the font is changing) but no effect on the
discomfort I experience.



[2]: http://www.infinality.net/blog/infinality-freetype-patches/


I haven't check that and will give it a try.


Try to identify what's causing your discomfort: Does your monitor
flicker when you're running Debian? Fonts too small/blurry? Bad color
scheme? Something else?


Well, actually, I don't think the fonts might be the main reason. Because the
phenomenon seems to be very subjective, I tried to explore this idea because I
knew some major differences in how Debian and Ubuntu deal with fonts existed.
But the unpleasant feeling is present (even if not so intense), just by looking
at the background of an empty desktop. It seems that the light is too intense,
too violent (even when I reduce the brightness) and that my eyes keep on
adjusting the focus with no interruption in an almost imperceptible manner.



Consider removing proprietary drivers as an experiment.


Sure I have to try that.


Yes, but better if you describe in detail what kind of pain you are
feeling because how the screen has to look like can be sometimes a
matter of personal preference


I tried to do so couple of lines above. Important point, I used to work with
Debian as my main OS some time ago (on Sarge, as far as I remember) on another
laptop with LCD screen, and never experienced this. I mean, if I agree that we
can't exclude the personal preference issue, I am not physically allergic to the
Debian environment



Mmmm... At a first glance I see nothing wrong from the xrandr output,
I mean, technically speaking both resolution and refresh rate values
are right.


Yes. Me neither. The only parameter I couldn't check (due to my lack of
knowledge) is the horizontal refresh rate. Any idea how I can get this value ?


/lionel





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Old 09-19-2012, 10:14 PM
Ralf Mardorf
 
Default Display hurtful on LCD screen with Wheezy

On Wed, 2012-09-19 at 23:40 +0200, Lionel Trésaugues wrote:
> The fonts (with the same hinting and antialiasing settings)
And the sub-pixel order is equal too?


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Old 09-19-2012, 10:22 PM
Shane Johnson
 
Default Display hurtful on LCD screen with Wheezy

Just a wild stab in the Dark here, could it be interlaced?
Shane

On Wed, Sep 19, 2012 at 4:14 PM, Ralf Mardorf <ralf.mardorf@alice-dsl.net> wrote:

On Wed, 2012-09-19 at 23:40 +0200, Lionel Trésaugues wrote:

> The fonts (with the same hinting and antialiasing settings)

And the sub-pixel order is equal too?





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Old 09-19-2012, 10:33 PM
Lisi
 
Default Display hurtful on LCD screen with Wheezy

On Wednesday 19 September 2012 22:40:30 Lionel Trésaugues wrote:
> Yes. Me neither. The only parameter I couldn't check (due to my lack of
> knowledge) is the horizontal refresh rate. Any idea how I can get this
> value ?

I still feel that a very minor difference in the refresh rates might be at the
root of the problem, but do not know how to check this. (I really do mean
minor: not large enough to be actually perceptible to you.) Perhaps someone
more knowledgeable than I might know how to investigate this. It probably
depends on HAL - perhaps there is some minor difference in the versions of
HAL in the different distros.

Lisi


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Old 09-19-2012, 10:38 PM
Mark Allums
 
Default Display hurtful on LCD screen with Wheezy

On 9/19/2012 5:33 PM, Lisi wrote:

On Wednesday 19 September 2012 22:40:30 Lionel Trésaugues wrote:

Yes. Me neither. The only parameter I couldn't check (due to my lack of
knowledge) is the horizontal refresh rate. Any idea how I can get this
value ?


I still feel that a very minor difference in the refresh rates might be at the
root of the problem, but do not know how to check this. (I really do mean
minor: not large enough to be actually perceptible to you.) Perhaps someone
more knowledgeable than I might know how to investigate this. It probably
depends on HAL - perhaps there is some minor difference in the versions of
HAL in the different distros.

Lisi




LCDs do not flicker.



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Old 09-19-2012, 11:03 PM
Lisi
 
Default Display hurtful on LCD screen with Wheezy

On Wednesday 19 September 2012 23:38:48 Mark Allums wrote:
> On 9/19/2012 5:33 PM, Lisi wrote:
> > On Wednesday 19 September 2012 22:40:30 Lionel Trésaugues wrote:
> >> Yes. Me neither. The only parameter I couldn't check (due to my lack of
> >> knowledge) is the horizontal refresh rate. Any idea how I can get this
> >> value ?
> >
> > I still feel that a very minor difference in the refresh rates might be
> > at the root of the problem, but do not know how to check this. (I really
> > do mean minor: not large enough to be actually perceptible to you.)
> > Perhaps someone more knowledgeable than I might know how to investigate
> > this. It probably depends on HAL - perhaps there is some minor
> > difference in the versions of HAL in the different distros.
> >
> > Lisi
>
> LCDs do not flicker.

I *explicitly* did not say flicker. I do not mean flicker. Flicker is
perceptible to the viewer.

Minitors *do* refresh. They do not all refresh at the same rate. The OP is
complaining of eye-strain and headaches. These are real, and quite
reasonably he would like to do something about it. They could easily be
explained by a tiny difference, far too tiny to be perceptible, or even
easily measurable.

This is the second time that you have contradicted me with the same irrelevant
comment, without offering anything constructive. Nihilism is not going to
solve the problem for the OP.

Lisi


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Old 09-19-2012, 11:49 PM
Ralf Mardorf
 
Default Display hurtful on LCD screen with Wheezy

On Thu, 2012-09-20 at 00:03 +0100, Lisi wrote:
> On Wednesday 19 September 2012 23:38:48 Mark Allums wrote:
> > On 9/19/2012 5:33 PM, Lisi wrote:
> > > On Wednesday 19 September 2012 22:40:30 Lionel Trésaugues wrote:
> > >> Yes. Me neither. The only parameter I couldn't check (due to my lack of
> > >> knowledge) is the horizontal refresh rate. Any idea how I can get this
> > >> value ?
> > >
> > > I still feel that a very minor difference in the refresh rates might be
> > > at the root of the problem, but do not know how to check this. (I really
> > > do mean minor: not large enough to be actually perceptible to you.)
> > > Perhaps someone more knowledgeable than I might know how to investigate
> > > this. It probably depends on HAL - perhaps there is some minor
> > > difference in the versions of HAL in the different distros.
> > >
> > > Lisi
> >
> > LCDs do not flicker.
>
> I *explicitly* did not say flicker. I do not mean flicker. Flicker is
> perceptible to the viewer.
>
> Minitors *do* refresh. They do not all refresh at the same rate. The OP is
> complaining of eye-strain and headaches. These are real, and quite
> reasonably he would like to do something about it. They could easily be
> explained by a tiny difference, far too tiny to be perceptible, or even
> easily measurable.
>
> This is the second time that you have contradicted me with the same irrelevant
> comment, without offering anything constructive. Nihilism is not going to
> solve the problem for the OP.

The refresh rate doesn't matter that much. If something changed than it
has to be changed, if nothing changed, than nothing happens. For a tube
monitor the picture is turned off and on and off and on. A LCD display
is always on.

"just by looking at the background of an empty desktop. It seems that
the light is too intense, too violent (even when I reduce the
brightness) and that my eyes keep on adjusting the focus with no
interruption in an almost imperceptible manner."

I suspect a wrong sub-pixel order for the fonts. If you look long enough
at the bad fonts, then perhaps even a blank background that is ok, seems
to be bad.

On Wed, 2012-09-19 at 16:22 -0600, Shane Johnson wrote:
"Just a wild stab in the Dark here, could it be interlaced?"

Computers don't use fields, so there only would be an effect for
interlaced videos, if no deinterlacing is done, but for the desktop
there is no interlace.


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Old 09-20-2012, 01:39 AM
lee
 
Default Display hurtful on LCD screen with Wheezy

Lionel Trésaugues <lionel.tresaugues@gmail.com> writes:

> First, thanks all of you to try to solve the issue I encounter with Debian.
>
> I will come back now to some of the points you mentioned in the discussion.
>
>> How important is it to you to be able to run Debian? Would it be
>> worth some spectacles, or some new ones if you already wear them?
>> (This solution worked for me.)
>>
>> Have you tried any of the rpm distros?
>
> I can live with other distributions than Debian, but I would like to
> use it as a base to setup a very lightweight working environment.

You can probably have that with other distributions as well.

> I found that the Ubuntu distribution contain a lot of extra-tools that
> I would not need, and their use in cpu resources is slightly higher
> than pure Debian (on the same hardware).

Then don't install these tools or don't use them. What do you actually
need? A window manager like fvwm or a tiling one like i3? Something
like gnome or kde or xfce?

> Nothing has really changed. This phenomenon appeared as soon as I
> started to boot into fresh Debian installation.
>
>> A minimum refresh rate of 72Hz is recommended (same as average human
>> heart rate) to minimize optical discomfort that you seem to be
>> suffering. Less than that the screen will often jump about and make
>> it difficult to see properly. See if you can do something about that.
>>
> I am running Ubuntu-based distro at 60Hz (on the same hardware)
> without experiencing this problem.

So it comes down to figure out what the difference between Debian and
Ubuntu is in that regard. You could show us some screen shots, one from
Debian, one from Ubuntu, showing the same thing (like a web page in a
web browser or whatever application you use most of the time). Perhaps
someone notices a difference.

>> Do the fonts look different in Debian? If so, in which way? If
>> they do, you could try to find out how they are rendered and try to
>> have them rendered the same in Debian.
>
> The fonts (with the same hinting and antialiasing settings) look very
> slightly blurrier on Debian than on Ubuntu.

So that is one difference, and it can be what causes your troubles. Are
you using the same fonts? Can you show us some screen shots and perhaps
a magnified part of the screen, produced with something like xmag?
Maybe looking at things through xmag reveals something that isn't
visible without magnification.

> Well, actually, I don't think the fonts might be the main
> reason. Because the phenomenon seems to be very subjective, I tried to
> explore this idea because I knew some major differences in how Debian
> and Ubuntu deal with fonts existed. But the unpleasant feeling is
> present (even if not so intense), just by looking at the background of
> an empty desktop. It seems that the light is too intense, too violent
> (even when I reduce the brightness) and that my eyes keep on adjusting
> the focus with no interruption in an almost imperceptible manner.

Are you using the same desktop backgrounds with the different
distributions?

> this. I mean, if I agree that we can't exclude the personal preference
> issue, I am not physically allergic to the Debian environment

Maybe you are

>> Mmmm... At a first glance I see nothing wrong from the xrandr output,
>> I mean, technically speaking both resolution and refresh rate values
>> are right.
>
> Yes. Me neither. The only parameter I couldn't check (due to my lack
> of knowledge) is the horizontal refresh rate. Any idea how I can get
> this value ?

Entries in /var/log/Xorg.0.log might give you some hints. If you're
using the NVIDIA drivers, you can use the nvidia-settings program to
modify some settings.


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Old 09-20-2012, 09:01 AM
Andrei POPESCU
 
Default Display hurtful on LCD screen with Wheezy

On Ma, 18 sep 12, 23:31:21, Lionel Trésaugues wrote:
> Hello,
>
> I am experiencing a physical pain whenever I am in front of my
> computer running either Debian (Wheezy) or Debian-based distributions
> (such as Mint LMDE, XFCE or MATE edition). Switching from XFCE to MATE
> doesn't lead to any improvements .

Have you tried just a plain console?

Kind regards,
Andrei
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