eye strain

[CNeub]

hello,

I have a Notebook with Intel Core i7 4710 - Intel Graphics 4600 and external Nvidia Gforce GTX 850M for about 2 weeks now. I connect the Notebook on two different places per HDMI with nearly three year old lg monitors. With my old Notebook (Intel Core2Duo and Nvidia Gforce 9500GT) I had not any problems with this two monitors. However when I connect one of the two monitors with my new Notebook I get eye strain and headache. Of course I use the right resolution FullHD and tried out different brigthness and contrast adjustments in intel graphic properties. OS is Windows 7 Prof x64 and the newest drivers are installed. Version:15.33.22.64.3621

Nearly two months ago I purchased an other Notebook with Intel Core i7 4700MQ - Intel Graphics 4600 and Nvidia Gforce GT755 M. I had the same problem there and so I sent it back, because I thought that the Notebook has an defect. I tried out Windows 7 and Windows 8 and had the same eye problems in the two different OS.Now I do not really know what the problem exactly is, because I have these problems with two different Notebooks on two different external LG Monitors and the integrated Displays of the Notebooks. But I thinkt the problem is the Intel HD 4600. Maybe that there is something wrong with the driver.Do you have any ideas about this? Couse I can't purchase and send back new Notebooks all the time.

Sorry for my bad english

[DKour]

Thank you raviprakash. This is very helpful. I'll keep it in mind.

[RPutc1]

You are welcome, _dimitri_.

Also, the following also might be related to PWM. I added acpi_backlight=vendor in my kernel parameters on my Toshiba laptop running Fedora 24 and it helped. And I am running at full brightness. Though, not every vendor releases drivers for Linux, Toshiba and Lenovo are few that do.

[DKour]

Thanks again, raviprakash

This is very useful info.

[TZohr]

Hi _dimitri_,

You have done a great job in helping to debug all this stuff, my great thanks to you.

I was thinking why I didn`t have this issue in my previous workplace 2 months ago and now I kind of start to see the whole picture. Before I was using Desktop machines like HP Z440 with LCD monitors which have CCFL for backlight source and I was very happy and didn`t knew what is eye strain. In the new company I have the notebook with intel hd4000 graphics card and a flickering monitor like HP Elite Display 27i. Can you help me with a couple of questions? Can you tell me if you have tried flicker free monitors and what was the result? What do you think if I change my workplace notebook into a desktop machine will the problem disappear or I still have to play with the IntelPWMControl program?

Regards

Tigran

[TZohr]

Also my great thanks to everyone who also did push this topic to this far:)

[DKour]

Thank you for your kind comment Tigranz. This has been an impossible situation that we all have had to deal with, so I think it's a good idea to try to help each other out while looking for solutions.

About the first question, I am not sure if any of the monitors on which I have never had any issue (even with the latest intel hd driver installed) was officially flicker-free. One is the screen of an ASUS K95VM and the other one the Surface 3. Either these screens do indeed have some sort of flicker-free technology or the driver just sets the PWM frequency to a level that is not irritating when it detects them, I suppose.

Mind you that the desktop monitor that I use at work, a Dell the model of which I do not remember, gives me no eye strain when connected to the desktop PC but does give me eye strain when connected to the Surface 3 via an HDMI cable (the very same Surface 3 which gives me no eye strain on its own screen). So the monitor does play a role but I am not sure in which exact way and trial and error is my only way to figure out a good setup.

This brings us to the second question. I think using a desktop PC might help, especially if it has an "external" GPU and does not use the intel hd chip or drivers. But you cannot be sure until you test the machine for a few hours in my humble opinion.

Finally I would advise everyone testing screens for irritation to be very strict during the tests because this eye strain issue creeps up on you as it builds up over time. Give your eyes a rest for a couple of days before testing a new monitor/computer to make sure they are not irritated from the previous setup and then try the new one. Then, if you are not sure whether it causes eye strain or not but you feel discomfort that gets worse rather than better over time, don't waste time wondering whether it's just your impression or not. You will just irritate your eyes further by insisting on trying to get used to your screen. For me, a setup that gives me no eye strain is pretty obvious. I can comfortably work on texts with a white background for example and, in the event that my eyes are still irritated from using a problematic computer, they just keep healing, even if I work 10 hours straight on my eye-strain-free machine.

[RPutc1]

You are welcome, _dimitri_.

Another thing that really helped me on top of the other things mentioned earlier was, getting around dithering. Mine is a Linux setup, and Windows probably does not do temporatl dithering. But posting details anyway, for what its worth.

My HP Envy laptop has a 6 bpp panel so reducing the color depth to 16 (from 24) along with specifying static dithering in Nvidia configuration helped getting rid of 'simmering' problem. This will probably need getting used to though. To achieve this, I added the following to the kernel parameters: video=eDP-1:1920x1080-16

The fomat is :x-

I can see in the kernel drm debug logs that the intel driver sets the dithering value depending on panel's bpp and X server's color depth. Not sure whether it can specify spacial vs temporal dithering to the panel, though. I guess it depends on the panel too.

[DKour]

Once again many thanks for this interesting piece of information raviprakash!

As far as Windows is concerned, I am not sure exactly what kind of dithering it does by default but I tried tweaking that too. I had found https://ledstrain.org/d/31-on-windows-7-eye-strain-is-gone-and-test-the-ditherig-exe a conversation which mentions a ditherig.exe program for Windows (everyone please note that I don't know if this program contains a virus. My AV did not detect anything but if you try it out, it's your responsibility). I could see it worked because, by changing the dithering settings, gradients on my screen got separated into bands of varying brightness. So I completely disabled dithering using ditherig.exe on Windows, but it didn't make much difference for my eye strain problem, even though I could actually see the changes it made on the screen. Changing the PWM frequency on the other hand provided immediate relief, without me being able to visually perceive any change on the screen.

[TZohr]

Recently I again tried the http://www.testufo.com/# test=blurtrail&foreground=FFFFFF&background=000000&thickness=1&height=480&ppf=2&separation=1000 Blur Busters UFO Motion Tests website. I increased the brightness to 100% to get rid of flickering. But when I change the "Pixels Per Frame" parameter from 1 to 16 I can see how the line is pulsating when I go over 3/5/7/9 Pixels Per Frame. If I lower the brightness to 50 it becomes more visible. Can you guys please try this test on your side, just start from 1 and incrementally go to 16 and see if 3/5/7/9 are pulsating? I have tried this test in multiple machines and most of them show pulsating, but the ones that don`t give me eyestrain(like my home notebook) don`t pulsate at all. Maybe this is the problem!!!

[DKour]

I'm not sure that it matters whether it is pulsating or not. I am on an old laptop right now and it pulsates at all framerates, probably due to the laptop's generally low performance. The important thing, in my humble opinion, is whether, at any given moment, we can see just one blurry line, even a pulsating one, or if we can discern multiple lines being rendered at the same time.

By the way, it seems I have been a bit unfair before with this blur trail test. It's fairly accurate at detecting PWM as far as I can tell after all.

Also, I have come across a lot of information over the past couple of days, mentioning how PWM is known to cause problems for some people when the "blinking" frequency is too low, sometimes even combined with some other factors like some manufacturing details of the screen and even the A/C adapter. If you google things like "PWM", "laptops without PWM", "PWM health effects" you can find it. There are even lists of computers that just don't use PWM or have it at an acceptably high frequency by default. In that sense, I suppose I have to apologise for maybe being a bit too harsh in my criticism of intel as this may not depend only on their products and drivers.

It would be nice if the feedback was a bit faster though and we received a bit more practical assistance. In my case, after everything I have tried and tested, I am sure that it is basically the PWM frequency that is causing me problems. If that is the case for everyone else, if we could have a user friendly tool for all platforms using the Intel graphics adapter (Windows, Linux, OSX) giving us the choice to increase the frequency up to a certain level that is acceptable, I am pretty sure we would be off their case. Currently IntelPWMControl is not working in many cases on windows and intel gpu tools are not user friendly on Linux and, again, I have had cases where they cause segmentation faults or have no effect on the values I am trying to change.

[RonaldM_Intel]

Hello _dimitri_

Actually yes, we noted 3 main causes for eye strain early on, and ways to check each cause, with PWM being the 3rd. The other two causes being Adaptive Brightness and DPST. There are more details about it in one of our earlier replies (reply # 62).

PWM settings are controlled by the Original Equipment Manufacturer (OEM) within their BIOS due to panels differing and PWM settings need to change from panel to panel. We advise anyone who can narrow it to PWM to please contact the OEM for help with their BIOS PWM settings.

Regards,

[DKour]

Thank you Ronald_Intel. In my case it is definitely the low PWM frequency that is causing me problems. I have already tested the other two factors and they did not make any difference, even though I thought that disabling DPST had helped in the beginning, due to wishful thinking.

Unfortunately, none of the machines I have tested provide a way to control the PWM frequency through the BIOS. Naturally I will see with the hardware vendors about any potential options for this.

Nonetheless, would you mind clarifying something for us? I have actually managed to change the PWM frequency on a macbook running Windows 7, using a modified version of IntelPWMControl. This and the existence of IntelPWMControl, as well as testimonials on the internet that some people have managed to do the same using intel gpu tools on Linux means that, at least in some cases, it is possible to modify the PWM frequency through the intel driver. Would this not also mean that perhaps in some cases the driver sets the frequency to a lower value than the maximum supported by a piece of hardware? Because in such cases, even if they are limited, it would be helpful to have some clear information about how far we can go through the driver and, even better, a user friendly method to do so.

[RPutc1]

Hello Ronald_Intel

Could you please post the equivalent i915 driver options on linux to achive the equivalent of /message/369554# 369554 Re: eye strain (reply # 62) related to Adaptive Brightness and DPST?

Thank you.

Ravi

[OVyno]

Unfortunately PWM is not the only reason that causes eye strain. I had a laptop without PWM and still had an eye strain with Intel videocard. And now I have a laptop Asus UL30A with OLD Intel driver that has PWM (you can see it using pencil-test) but NOT causing eye strain. New Intel drivers on the same notebook cause eye strain. Of course, it will be great if there will be option to change PWM frequency in the driver options, but it is not the only reason, unfortunately.

[DKour]

You are probably right valex13

The ASUS laptop I keep mentioning does have PWM from what I see on the blur trail test but it doesn't cause me eye strain. I only know that PWM caused me eye strain on the three other machines I either own or have worked on, and that changing the other "suspect" settings mentioned by intel, apart from PWM, did not help resolve the issue, so this is what I have reported.

[SMohd2]

Ronald_Intel

Hi Ronald, I have a suggestion for a solution to this eye strain problem.

Generally, here is what we know about the intel graphics driver and eye strain:

• Standard VGA driver - no eye strain
• Older (pre 2011) Intel graphics driver - no eye strain
• Newer (post 2013) Intel graphics driver - eye strain

In my earlier posts, I attached 2 sets of drivers, one which is pre-2011 which does not produce eye strain, and one which was released in 2013 which does give eye strain. I suggested for Intel to compare what features were added in the 2013 driver (that was not present in the 2011) driver, as those are the likely suspect as the cause of the eye strain. But you said this is not possible because from the 2011 driver to the 2013 driver, there are many versions had been released in between, and that it would be difficult to track all the changes made between these 2 drivers. Ok, in that case, can we try another approach.

We know that the Standard VGA driver does not cause eye strain. But I cannot use the Standard VGA driver for my daily use because (at least for me) it lacks 2 very important features, which is brightness control and the ability to use projector (via VGA port or HDMI port), which is absolutely essential for my office work. So, while the process of identifying the root cause of the eye strain is on-going, can Intel work on a temporary or workaround solution first, which is to take the Standard VGA driver as base, and simply add the brightness control and the display out (ability to use projector via VGA port and HDMI port) first?

If Intel can do this, at least those of us who suffers from Intel graphics driver related eye strain can have a (temporary/workaround) solution so that we are able to use our Intel-inside laptops without getting eye strain. Ronald, can your team develop a beta graphics driver based on the Standard VGA driver, and add brightness control and display out features?

I and I'm sure many of us here would be happy to test the beta driver to see if it works (i.e. no eye strain) or not. If it works, and it does not produce eye strain, then Intel can add on more features and functionality to the driver and we test it along the way to make sure whatever new feature that are added does not produce eye strain, until we find out one that does. That would be the cause of of the eye strain, finally identified. Can we try this approach? Look forward to hear from you, Ronald.

[OVyno]

Can confirm every your conclusion. There is another option: Ronald, is it possible to get the 2011's Intel videocards driver code and just to add the support for new videocards (added from 2011) not adding other new features and options?

[RonaldM_Intel]

Hello all,

On getting the standard VGA driver with just brightness and display out features, it is quite challenging because our drivers are meant to be generic so OEMs can customize them, and also they have to be optimized for so many different panel types. Still, let me see what we can do about it. I'll get back to you as soon as possible.

I find quite interesting that for _dimitri_ his eye strain even occurs with a laptop using non-Intel graphics. Perhaps it circles back to PWM settings.

Regards,

[SMohd2]

Ronald_Intel

Hi Ronald...it has been 2 months since your last post here. Any update on the standard VGA driver with brightness control and VGA/display out capability? Are you guys developing the driver now? When can we expect the completion of the driver? I am eager to test it.

Looking forward to hear from you soon.

[SMohd2]

One of the suspect of the cause of the eye strain is dithering / temporal dithering. I came across this thread on the subject:

It seems that dithering is enabled by default in Intel graphics drivers, and that there is no way for a user to disable / toggle it. Is possible to develop a beta graphics driver that the user can toggle the dithering, some menu to enable or disable it? Or develop a beta graphics driver, one version with dithering enabled and another version with dithering disabled. Then we can test both and see if without dithering, does it help to reduce or eliminate eye strain or not. At least we can confirm or eliminate on the of main suspect of the root cause of this eye strain.

[CNeub]

I recently came up with another theory. Since it is very very exhausting and difficult to look between all changes of the two driver versions Kray_62 mentionend, will it possible that you intel guys maybe take a look at the icc color profiles. Are there any changes? Kray_62: I dont know it this is even possible, but maybe you can try out to extract the icc color profile of your old driver and try to use this old icc color profile with your new driver. You can find the path of the icm file in the device manager -> monitor -> driver -> details...

Edit: If you need more information for what I exactly mean, you guys can text me everytime you want. However please really take a look at this. Cause if you don't install a special color profile from your monitor driver, the system will use a certain color profile from microsoft or the graphics driver. Maybe there are color profiles which some of us really really harm us, however I'm not an expert, but once again please do not ignore this idea. It should be simple that somebody of us test an older (trusted) color profile with a newer driver and replace the new color profile there.

This can explain why I also get eyestrain with my trusted old lg monitors (LED and non LED) if there is a new notebook connected and no eyestrain with my meanwhile seven year old notebook with old nvidia graphics card and very old driver version. This really is a thing of different driver versions and different hardware. I was always very sceptical if pwm or dithering is the reason, since why should an graphics driver change those things of an monitor in that way that the monitor will harm me. Also pwm free monitors and those things never made any difference for me...