Maxx

I think the issue I have with some software, such as games is if they update the game engine or whatever or change the way colors are presented / flicker etc is what gets me. I want to be able to try things with a 144hz screen but at 75hz still an issue. There are some games that I've played and refunded that trigger my symptoms immediately so I believe its also related to game engines etc again.

I get what you mean though, it can be very stressful to be told you're stressed when you're not!

The PWM / eye bloodshot is easy to proove as you say. Think of a strobe light when describing it, think what your iris is doing, opening and closing rapidly as the light flickers and this with slight eye movment causes the muscle pain around the eyes.

Maybe with flicker at 1000+hz some people have eyes that still react in such a way thus making the eyes tired and red, then people like me also get migraines from it - but again I still dont think these are migraines / they are a different sort of migraine.

I'm 3 or 4 days into one now, its levelling off. I have a Lenovo t440 on the way that should have a TN screen so I have some hope that my migraine is totally gone soon and this new old laptop will be ok

    I have clear evidence that my eyes get red with PWM of 2400Hz. I had Sony Xperia phone that had 2400 Hz PWM at 33 brightness. When ever I let auto brightness lower it or manually lowered it, my eyes got red. Finally I just kept it manually over 33 and I had zero problems with it for the 2,5 years that I had it.

    I know it sounds unbelievable and sites like notebookcheck also kinda claim that it is not possible to sense such high frequencies, but my eyes do without a doubt. Anyone could verify this by seeing my red eyes.
    If the ears sense 20Khz why would the optic nerve be able to sense 2,5Khz? I dont claim that I see the flicker, the flicker just makes my eyes bloodshot.

    • JTL replied to this.

      I dont mean to hijack this thred but I've recieved my Lenovo T440, intel 4300u HD4600 - although even after updating the drivers its reported as 'intel HD graphics family' - I know its not a new machine and used is hit and miss.

      Either way as I suspected / hoped this machine is totally fine for me to use - it doesnt appear to have PWM but as it was used it is not in amazing condition but refurbished to a high standard and around 1/3 the price of the HP envy that I returned recently.

      Its got a HD TN screen that is very poor even for a TN and very dim - but this is good for me. I actually have 2 other IPS screens that should fit so I can experiment with that.

      Hoarding old Lenovos appears to be the way forward at least for me. Annoyingly I can buy the same machine again for cheaper now but I'll hold off I think.

      I do agree with the comments on Notebookcheck, sometimes they're wrong as well and devices they test have PWM - but this may be regional / panel differences, but yes I do believe some people, myself included can detect and be affected by very high frequency flicker / PWM.

      • Maxx replied to this.

        HAL9000 Yes it would be interesting to know what is it that makes an older Lenovo TN or IPS good for us, but newer with better color screens are not. PWM is an issue for me in those Lenovos also, so I have to keep the brightness at 100% as not to have the PWM enabled.

          just a status update. I had to return the Lenovo Legion 5 Pro. I was able to used it a full workday, but in the afternoon my eyes started to feel strained and then the whole evening my eyes were irritated and dry. Not that badly bloodshot as with a PWM screen, but clearly there is some flicker in that screen, maybe from temporal dithering.

          Again, I could rest my eyes with the HP desktop monitor or a Sony TV after using the laptop for a day. So it is not my eyes per se, it is the bad display.

            Maxx So at the end, what do you keep? The Asus notebook with OLED screen?

              I'm still testing the Asus Oled. Not sure yet, as I've not had a chance to used it like I would on a typical workday. But I'm pretty sure it is better than the LCD screens. I use it over 52 brightness where there is only a minor dip in the brightness at 60Hz.

              I was able to use Galaxy S2 6 years ago without problems, it was and has been practically the Only Oled phone without PWM.

              Maxx I have clear evidence that my eyes get red with PWM of 2400Hz. I had Sony Xperia phone that had 2400 Hz PWM at 33 brightness. When ever I let auto brightness lower it or manually lowered it, my eyes got red. Finally I just kept it manually over 33 and I had zero problems with it for the 2,5 years that I had it.

              I once read a paper from the "lighting industry" that claim that some of the effects of PWM persist up to around 10KHz, but I'm not entirely sure of the methodology involved.

              • jen replied to this.

                  So, the Asus Oled is going back as well.

                  After using it a full day and also in the evening, my eyes are quite irritated today.

                  After testing 5 laptops from different manufactures, Intel / AMD. LCD/Oled, there just is not a modern laptop that I could use.
                  I probably could survive with the OLED, ensuring its above 52% brightness. But I would need to limit my daily usage to a few hours. Only time would tell how much I could use it on a daily basis. But then again, there will be long workdays when I need to watch the screen for 10-12h, so I need a laptop that will not irritate my eyes.

                  Now I'm "resting" my eyes with this HP desktop monitor for today and maybe I'll try a couple of days more, but it is clear that the OLED is also straining my eyes.

                  Some people would say that of course your eyes get tired after watching a screen for 10 h. No, they will not get tired watching this HP desktop monitor or an older Lenovo with poor screen. They will also not get tired watching a Sony LCD TV without PWM. Nor reading a book even in situations when I have a real page turner and read it during the day and most of the night.

                  So the problem really is in the screens, not my eyes. Yes, my eyes might be more sensitive than most people, but manufactururers should still be able to make screens that do not irritate the eyes.

                  I've heard this countless times from people who are oblivious to this problem that their eyes get tired or they get a migraine after a long workday. It IS the flickering in the screens that is causin the issue, it is not their eyes or their migraine. They would not have the problem with a screen that does not flicker.

                  It is also not blue light. The blue light hype is the most outrageous marketing bs that is going around nowadays. These Eye Care moninors that supposedly emit less blue light. People's eyes do not get strained outdoors on a clear sky day, thought the amount of blue light is massive in comparison to any screen available. Blue light does not irritate eyes. Flicker does.

                    The vendors have had so many claims about irritaeted eyes, that they have come up with the marketing idea that it is blue light that is the problem, as they are not able to manaufacture screens that would have 100% RGB coverage and would not have temporal dithering.

                    One thing I would like to confirm is to get a 10 bit desktop monitor without PWM, to see if the lack of temporal dithering would show that it really is the 8 bit + 2 bit FRC that causes the issue. I'm pretty sure it is. In my case the drivers or the other hardware does not have any affect. It is the actual display panel tech that is causing the issue, since no matter what hardware and software I have with the HP desktop monitor, it will not irritate my eyes. Also if I connect a laptop that irritates my eyes to this HP desktop monitor, it will not irritate my eyes, but the laptop panel will.

                    • JTL replied to this.

                      Maxx People's eyes do not get strained outdoors on a clear sky day, thought the amount of blue light is massive in comparison to any screen available. Blue light does not irritate eyes. Flicker does.

                      I think the issue there isn't with "blue light" per se, but the fact that the blue spectrum dwarfs all the other spectrum

                      @TechSensitive did an article some time ago measuring the spectrum of various other "lights" (sunlight, quantum dot backlit LCD, etc.)

                      https://techsensitive.com/how-sunlight-is-different-from-leds-and-other-lights/

                      Can really see the difference between the two plots...

                      Maxx One thing I would like to confirm is to get a 10 bit desktop monitor without PWM, to see if the lack of temporal dithering would show that it really is the 8 bit + 2 bit FRC that causes the issue. I'm pretty sure it is. In my case the drivers or the other hardware does not have any affect. It is the actual display panel tech that is causing the issue, since no matter what hardware and software I have with the HP desktop monitor, it will not irritate my eyes

                      Some dithering is done by the GPU itself, and some GPUs can be rather obnoxious about it (speaking from experience). I have my own video capture solution that can detect it in (most of) those cases.

                          Yes, this is clear, the spectrum favors blue light. But the blue light from a screen is 1 and the blue light from the blue sky is 100 or more. So even if the spectrum favors blue, I don't buy the idea that it would irritate the eyes.

                          Macular degeneration or some other very long term eye problems could arise from staring a blue light 10h a day, I think there is some science behind that, but I have not seen any science that looking at a non flickering blue light would irritate the eyes.

                          In the article suns spectrum is measured most likely by taking direct sunlight. But what is the spectrum if they would measure only the light that reflects back from the blue sky?

                          Or what if a person is in a room painted blue lit by blue light. I don't think there would be any eye strain

                          So I do understand thei point with the blue light but my opinion is that it is just hype generated by marketing people, I have not seen any scientific studies showing that the blue light from a non flickering light source would irritate the eyes.

                          I think that in most cases they have just mixed flicker with blue light as the flicker is something (temporal dithering) that cannot be measure.

                          Could you detail your rig how you video temporal ditering?

                          • JTL replied to this.

                            Maxx Yes, this is clear, the spectrum favors blue light. But the blue light from a screen is 1 and the blue light from the blue sky is 100 or more. So even if the spectrum favors blue, I don't buy the idea that it would irritate the eyes.

                            I've personally seen flicker free blue LEDs on certain electronics of bright intensity, and it's not very pleasant to look at.

                            I don't buy that even in the case of a flicker-free display with no dithering that "everything is entirely fine, move along", hence the drive for more research.

                            Or what if a person is in a room painted blue lit by blue light. I don't think there would be any eye strain

                            I mean, this kind of brings back an earlier point of mine. CRT monitors had a more even spectrum compared to "modern" WLED backlights, and I don't recall people obsessing over color temperatures with those.

                            I think that in most cases they have just mixed flicker with blue light as the flicker is something (temporal dithering) that cannot be [measured].

                            Could you detail your rig how you video temporal ditering?

                            There are still many unknowns with the dithering problem, one being that the display outputs on a laptop versus the connection used for the internal LCD do differ, so it's not trivial to reliably detect dithering on a laptop as using the internal LCD.

                            I haven't written up all my notes and testing, but here's some info on my project "VideoDiff"

                            https://ledstrain.org/d/848-project-videodiff
                            https://wiki.ledstrain.org/docs/appendix/tests/dithering/

                              @JTL Yes, I agree that staring at a blue light for hours every day might not be good for eye or sleep health. So I agree that the lightspectrum should be as close to natural sunlight as possible.

                              But does the blue light spike in the spectrum actually cause any significant eye strain? Not at least for me and presumably to most people, since most people do not experience any eye strain from any screen, even with PWM or Temporal Dithering.

                              So that's why I argue that the marketing BS about blue light is misleading as it tries to connect blue light to eye strain, while most people do not experience any eye strain with screens. Those who do, the cause is most of the time PWM or dithering.

                              I was thinking if the dithering could be detected by purchasing a cheap microscope and filming that with a dlsr or even mobile phone.

                              JTL I once read a paper from the "lighting industry" that claim that some of the effects of PWM persist up to around 10KHz, but I'm not entirely sure of the methodology involved.

                              This may have been a reference to this 2011 paper by Bullough et al. where 20% of people could still notice the stroboscopic effect of flicker at 10,000Hz. They did not test higher frequencies, so did not determine at what frequency no one can detect flicker. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.876.126&rep=rep1&type=pdf

                                hi, i use the razer studio 2020, with the quadro 5000, older driver, but the screen is pwm free, one of the very few. maybe test it as it works for me really well.

                                  @Phip Is it the OLED version - that surely cannot be PWM free?
                                  Are you in the same situation that PWM AND temporal dithering is a problem?

                                  • Phip replied to this.

                                    Just realized that my HP ZR2740w is a 10 bit (8+2 FRC) so Temporal dithering? I don't know. But this monitor has given me zero eye strain for the past 10 years no matter how much I used it and with what kind of hardware.

                                    The only thing I can think of is that I have some 5 years old Nvidia 970 card - maybe that then did not yet have the technology that the newer ones have, which is producing the eye strain in more recent laptops?

                                    Oh what a frustrating problem this is. I may need to start hoarding old Lenovos to be able to work eye strain free when not at home.

                                    dev