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Old 09-20-2012, 12:18 PM
Mark Allums
 
Default Display hurtful on LCD screen with Wheezy

On 9/19/


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





Nihilism?

Apparently, you don't understand the comment.


LCD do not refresh in the same sense as CRTs. They project a continuous
picture. If a pixel doesn't change, it stays lit. No fading. OPs
problem is not due to refresh, unless it is a CRT.


His problem is probably due to environmental factors. E.g. display too
bright, viewing angle causing neck strain, or eye strain, color
balance/gamma subtly off, etc.


You are obsessed with refresh rate, but it's a useless thing to focus
on, because refresh rate is about flicker, and LCDs don't flicker.





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Old 09-20-2012, 12:22 PM
Mark Allums
 
Default Display hurtful on LCD screen with Wheezy

On 9/19/2012 6:49 PM, Ralf Mardorf wrote:

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.




Yes, an incorrect setting on the subpixel rendering might cause
eyestrain. Getting the RGB ordering in the right order would be helpful.


Good suggestion.








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, 12:55 PM
Lisi
 
Default Display hurtful on LCD screen with Wheezy

On Thursday 20 September 2012 13:18:58 Mark Allums wrote:
> On 9/19/
>
> >> 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
>
> Nihilism?
>
> Apparently, you don't understand the comment.
>
>
> LCD do not refresh in the same sense as CRTs. They project a continuous
> picture. If a pixel doesn't change, it stays lit. No fading. OPs
> problem is not due to refresh, unless it is a CRT.
>
> His problem is probably due to environmental factors. E.g. display too
> bright, viewing angle causing neck strain, or eye strain, color
> balance/gamma subtly off, etc.
>
> You are obsessed with refresh rate, but it's a useless thing to focus
> on, because refresh rate is about flicker, and LCDs don't flicker.

>> LCDs do not flicker.

I also used a Samsung SyncMaster (recognized as *CRT* by
nvidia-settings)

Lisi


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Old 09-20-2012, 01:59 PM
Andrei POPESCU
 
Default Display hurtful on LCD screen with Wheezy

On Jo, 20 sep 12, 07:18:58, Mark Allums wrote:
>
> LCD do not refresh in the same sense as CRTs. They project a
> continuous picture. If a pixel doesn't change, it stays lit. No
> fading. OPs problem is not due to refresh, unless it is a CRT.
>
> His problem is probably due to environmental factors. E.g. display
> too bright, viewing angle causing neck strain, or eye strain, color
> balance/gamma subtly off, etc.
>
> You are obsessed with refresh rate, but it's a useless thing to
> focus on, because refresh rate is about flicker, and LCDs don't
> flicker.

I have however seen LCD monitors behave significantly different
depending on refresh rate. Entire areas were blury, but everything was
fine when I switched to another refresh rate (60Hz -> 75Hz if I remember
correctly).

Kind regards,
Andrei
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Old 09-20-2012, 02:37 PM
Mark Allums
 
Default Display hurtful on LCD screen with Wheezy

On 9/20/2012 8:59 AM, Andrei POPESCU wrote:

On Jo, 20 sep 12, 07:18:58, Mark Allums wrote:


LCD do not refresh in the same sense as CRTs. They project a
continuous picture. If a pixel doesn't change, it stays lit. No
fading. OPs problem is not due to refresh, unless it is a CRT.

His problem is probably due to environmental factors. E.g. display
too bright, viewing angle causing neck strain, or eye strain, color
balance/gamma subtly off, etc.

You are obsessed with refresh rate, but it's a useless thing to
focus on, because refresh rate is about flicker, and LCDs don't
flicker.


I have however seen LCD monitors behave significantly different
depending on refresh rate. Entire areas were blury, but everything was
fine when I switched to another refresh rate (60Hz -> 75Hz if I remember
correctly).



I have never owned an LCD/LED monitor that one could change that setting
on. And I've owned quite a few.


Not in any OS, Debian, Ubuntu, SuSE, Mandriva, Fedora, Arch, Gentoo,
Slackware, PCBSD, FreeBSD, Haiku, Windows in any form or version, nv
driver, Nvidia driver, Nouveau driver VESA, Matrox, Cirrus logic, Intel
driver, Bare metal or native or Virtualbox or VMWare or Xen or QEMU, any
version of Xfree86, X.org, Wayland, KDE3, KDE4, GNOME 2, GNOME 3, MATE,
Cinnamon, XFCE, Open box, bare X, LXDE, Unity, Moblin, LightDM, KDM,GDM,
XDM.


Never had that experience or heard of it or dreamt of it.

There do exist bad LCD panels. Blotchy, dim in one quadrant, bad
pixels, pixel memory, ghosting, terrible response time, bad contrast.


Live and Learn.


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Old 09-20-2012, 02:43 PM
Camaleón
 
Default Display hurtful on LCD screen with Wheezy

On Wed, 19 Sep 2012 23:40:30 +0200, Lionel Trésaugues wrote:

> 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.

(for the next time consider individual replies instead putting all the
bunch in the same basket ;-) )

>> 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

Okay, but the given description is not enough. Can you upload a snapshot
of what you see in your screen and what's what you find unpleasure? That
way we will able to give you more hints.

>> 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 ?

The standard refresh rate for TFT/LCDs is set at 60 Hz. which is your
current value (unless you have a very special or super high quality
display).

Greetings,

--
Camaleón


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Old 09-20-2012, 02:51 PM
Lisi
 
Default Display hurtful on LCD screen with Wheezy

On Thursday 20 September 2012 15:37:54 Mark Allums wrote:
> Never had that experience or heard of it or dreamt of it.

You obviously feel that your experience is more valid than anyone else's when
it comes to monitors. But you appear to know nothing at all about
eye/eyesight/eyestrain problems and headaches.

You couldn't have heard of it, since you discount any mention you *do* hear.
And it is irrelevant whether you have experienced or dreamt of it. There
must be a good many disabilities, illnesses and physical problems about which
you know nothing or very little, and hopefully many more of which you have no
experience.

Lisi


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Old 09-20-2012, 03:01 PM
Lisi
 
Default Display hurtful on LCD screen with Wheezy

On Tuesday 18 September 2012 22:31:21 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.
>
> I don't have this feeling at all when I am running either Ubuntu or
> any Ubuntu-based distribution (Mint XFCE or Cinnamon edition).

Is there any possibility that more of the ultra-violet end of the spectrum
might be displaying in the Debian list of distros than in the Ubuntu list?

If so, that could certainly cause the problems that Lionel mentions, but I
know too little about the colour reproduction involved to know whether it is
possible. If this could be the case, how could Lionel change it?

Lisi


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Old 09-20-2012, 03:16 PM
Andrei POPESCU
 
Default Display hurtful on LCD screen with Wheezy

On Jo, 20 sep 12, 09:37:54, Mark Allums wrote:
> >
> >I have however seen LCD monitors behave significantly different
> >depending on refresh rate. Entire areas were blury, but everything was
> >fine when I switched to another refresh rate (60Hz -> 75Hz if I remember
> >correctly).
>
> I have never owned an LCD/LED monitor that one could change that
> setting on. And I've owned quite a few.
>
> Not in any OS, Debian, Ubuntu, SuSE, Mandriva, Fedora, Arch, Gentoo,
> Slackware, PCBSD, FreeBSD, Haiku, Windows in any form or version, nv
> driver, Nvidia driver, Nouveau driver VESA, Matrox, Cirrus logic,
> Intel driver, Bare metal or native or Virtualbox or VMWare or Xen or
> QEMU, any version of Xfree86, X.org, Wayland, KDE3, KDE4, GNOME 2,
> GNOME 3, MATE, Cinnamon, XFCE, Open box, bare X, LXDE, Unity,
> Moblin, LightDM, KDM,GDM, XDM.

I can get you the exact model numbers if you insist, but from memory,
it's an older 4:3 17" HP LCD, connected via VGA to an older HP desktop
(P4) with integrated Intel VGA adapter, running Windows XP.

Kind regards,
Andrei
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Old 09-20-2012, 03:23 PM
lee
 
Default Display hurtful on LCD screen with Wheezy

Andrei POPESCU <andreimpopescu@gmail.com> writes:

> I have however seen LCD monitors behave significantly different
> depending on refresh rate. Entire areas were blury, but everything was
> fine when I switched to another refresh rate (60Hz -> 75Hz if I remember
> correctly).

How did you do that? I thought their rates cannot be switched. The X
server tries to go by what EDID data it reads from the monitor, and I
don't have any other data available.


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