So I'm starting this thread just to keep it in one place. As promised - first video of Macbook's screen showing different shades of Red, Green and Blue (brightness going down in 3 phases for each color) is here: https://vimeo.com/292002526 (go fullscreen to make the flicker more visible - on the embedded version it's not so obvious) I wanted to clear it a little bit, just to make it shorter and add some captions, but finally just uploaded the full content, due to lack of time to master the video editing software and rendering capabilities of my 8 year old laptop that I use currently. The setup consisted of Macbook Pro 13 2015 screen as a victim, HTC 10 in 120 fps slowmo as camera and an old russian microscope that promises to give 60x zoom. Anyway - if you browse through this video, you'll see that when the light goes down on red (around 4:30) and green (15:30) pixels, some funny thing begins - pixels tend to make pulsing glows, brighter and darker "lines" of pixels come one after another - the darker the color gets, the more it is visible, so carry on watching if you don't see it at first. Another thing is visibility of the same issue on blue subpixel - as I look on my computer - it pulsates a little bit, but not as much as the other colors, which is strange. In next days (probably more around weekend) I'll be testing different scenarios and different screens, so please share any ideas that may be interesting. I'm also open on suggestions on free video editing software and online video sharing platforms as I'm a newbie in this area.

I have an update (a long one). I've tested several screens in different setups: Macbook pro 13 2015 Ipad Pro 10.5 (2017) Iphone 8 plus Dell e5480 Asus ZenPad S 8.0 HTC 10 I've tried recording microscope view on all of them with iPhone 8 plus (240 fps) or HTC 10 (120fps). HTC 10 seems to catch flickers better so I finally used it instead of iPhone 8+ (I only checked HTC 10 with iPhone's camera). Test consisted of running HTML page with a JS script that started with color shades of higher brightness going down to lower values. At first I started with 255 (highest) value for Red, Green and Blue and was going down to 0, but then noticed that most interesting part is between 100 and 0, so I started there and went down in increments of 20. To give you some input - here's how I perceive (and rate) all the above screens: Macbook pro 13 - (3/10) father of all the eye strain, can't use it anymore for longer periods Ipad pro 10.5 - (8/10) I couldn't use it for a long time when Macbook pro 13 was in action, but now it's fine, I don't get strain with it, just minor tiredness from using a screen Iphone 8+ - (6/10?) it's my wife's phone, so I don't use it often, at first it seems nice, but after some time it has some hints of straining features (screen to sharp, some brightness issues, etc.) Dell e5480 - (4/10) I can use it for a while, but it's generally straining my eyes, not to the level of Macbook, but still unusable Asus Zenpad S 8 - (6/10) medium strain after longer usage, ok for shorter sessions HTC 10 - (8/10) same as Ipad pro 10.5 - I wish all the screens I have were of the same quality. No strain, apart from standard tiredness after long sessions Now let's dive into results: Macboook pro 13 - obvious flickering on subpixel level for many color shades / steps of brightness Ipad pro 10.5 - no noticeable flickers, maybe a little bit at lower brightness, but not as aggressive as these of MBP 13 (by the way - it has a little bit different shape of subpixels - they look a little bit like half-moon) Iphone 8+ - it flickers on lower brightness levels, a little better than MBP 13 Dell e5480 - it flickers similarly to MBP 13, on top of that it has PWM on everything below 100%, so it's a double winner 😃 Asus Zenpad S 8 - flicker on lower brightness levels, didn't seem to be so aggressive HTC 10 - no noticeable flicker, maybe a little bit at the lowest setting (a different layout of subpixels - they're formed into "stairs", not standard vertical lines) As you can see, only HTC 10 and Ipad 10.5 didn't produce obvious flicker on these tests and it matches my feelings about them - they're the only 2 screens I can use on daily basis, other ones (apart from Iphone) are worse. Below you'll find the video with examples of different screens - at first it's just red subpixel part (red and green subpixels proved to reveal flicker the best) and then as a bonus I made a video of webpage browsing on my Macbook, which also shows different flickers (this time not isolated to just one color). As usual - open it up in full screen as flickering is more obvious then. https://vimeo.com/292764049 I'm not sure if it's actually FRC or dithering there, but at least it proves that, even when not clearly visible, there's a hell lot of flicker on our screens. Another important thing is relation between screens that are bearable for me and these who don't seem to flicker. I just don't know how to test these screens at shops, I won't be able to put them under the microscope 😉

This is great. Though could it be this is neither FRC nor temporal dithering but regular polarity inversion? http://www.lagom.nl/lcd-test/inversion.php I am also curious to see how Firefox Quantum's pixels behave in contrast to a known-good browser (or maybe better, a screenshot of the same Firefox window). But I don't know if it acts the same on Mac. Edit: Plus further tests like switching temp. dithering on and off with working tools like "ditherig", Nvidia-Settings or several open source Unix drivers like nouveau, radeon, amdgpu, which claim to offer control over the dithering status.

It could be inversion too, but it would probably manifest itself on higher brightness, I could only spot it clearly when saturation of color was below 40%. Also if you look at examples of browsing the real webpage the parts that flicker are mostly on edges of fonts, dark areas, which also suggests some kind of dithering to get better colors. Anyway I’ll have to check how lagom’s test looks under microscope - that’s a good idea 🙂 Regarding Quantum - I haven’t checked it, I hope the difference between standard browser and Quantum can be observed with my gear, but if it’s subtle I doubt that it will get caught. Could you share any specific websites that are worse on Quantum? Or recommend another browser that is better to test it against. Speaking of software - I looked at the gray color of the new GMail which is also cursed, but haven’t spotted anything different so far - probably it’s a mix of gray text on gray background, awkward Chrome font rendering and general usage of gray colors which are composed of all R, G, B in different shades which makes flickering more likely. Reddit under chrome is another interesting case of how bad a website can look now. I’ll also check if Ditherig changes anything on different machines, but I couldn’t spot the difference with bare eye on my newer laptops, probably it doesn’t support modern graphic cards from Intel. I’ve only seen it making a change on an older HP DV6 (bars instead of gradient), but this laptop is close to impossible to be put under this microscope (broken charging port requires it to be positioned carefully to operate). I don’t use Linux on a daily basis so I’ll probably check it one day, but not soon. It would be more interesting if there was a known distribution / version that is helping in some cases. It could lead to software, not hardware solutions which would be better for us. By the way - does anyone have access to a microscope (any semi-professional with zoom around 50-60x should be enough) and a camera that is better than one on the phone? I may be limited with this stuff, however I’m not sure what factor is the most important for camera. I hoped for better results with Iphone, but it proved to see less flicker, probably due to some aggregating / averaging algorithms used to make videos more fluid.

andc Could you share any specific websites that are worse on Quantum? Any site, they changed something in their engine between 56 (.02 I think) and 57+. https://ledstrain.org/d/297-firefox-quantum-57 I believe the lagom black level test is good for testing for temporal dithering in general. I could clearly see 6 bit both temporal and static dithering in some of the black boxes when switching on and off via the graphics card driver (8 bits were hard to see). However, we don't know where the Firefox eye strain is coming from. But it must be something that changes over time, for screenshots can be looked at in external image viewers without eye strain.

andc Nice results man! One thing that I am curious about is that if different color profiles on the macbook change the flickering at all. For example that deep-red with not the default screen color profile (color LCD) but for example with Adobe RGB (1998). And maybe with truetone/nightshift on and off if you have one of the newer versions of OS. Cheers and thank you for testing this out!

I've tested it briefly with Night Shift and F.lux and could see flicker, especially on lower brightness settings, but I'll try to catch it again on the video. Basically what F.Lux / Nightshift does is adding a little amount of red color to the tone (or removing amount of blue, which gives similar output), and it results in making red pixels brighter. In case red component is already there, it might be fine (as I couldn't see flicker on higher brightness of pixels), but if only blue / green subpixels are used, it can add more flicker as it will probably activate red subpixel in low brightness (which seems to equal additional flicker). I'll check different color profiles, I'd guess, if "Color LCD" is tuned for this particular display, they should add more flicker due to missing sweet spots. The problem with observing whole pixels instead of just subpixels is that it's harder to see the flickering - three subpixels at once are brighter than individual ones which somehow misleads camera. You can check it on the second part of my video where I browse a webpage - there is some flicker, but it's not as noticeable as this on isolated "red" examples. It would be great if someone had better equipment, maybe then we could see the flicker on higher brightness and also observe whole pixels without issues. Thanks for your comments guys, many useful ideas, just need to find time to test everything properly 🙂

Thank you! I have a few questions to understand this better - -it only shows in certain areas when you decrease brightness, so you wouldnt see it everywhere on the screen? -isnt the light that lights the pixels still the backlight? But the pixels can dim I understand, so even if the backlight is flicker free, the pixels make it appear as flicker? -is it software controlled? -if it is, we need to send this to a few people, if you dont wanna do it I can do it - mostly Daniel Georgiev, who programmed iris and could be capable to use this information to program a cancellation of this effect into his software too.

martin martin it only shows in certain areas when you decrease brightness, so you wouldnt see it everywhere on the screen? Based on what I saw - it depends on how bright given subpixels are. Each color in HTML and on screen (as a pixel) is built of Red, Green and Blue components whose shades range in value from 0 (pure black) to 255 (full brightness, clearest shade of R, G or B ). From what I've seen - flickering is usually noticed by my phone's camera if subpixel shade goes below 100 (around 40% of 255 max value). So it seems that if you go below 40% of native brightness every pixel/subpixel may start flickering. Also if pixel is generally bright, but contains deeper shades of specific colors (like a touch of red provided by F.lux or night watch) these deeper shades will probably flicker. martin -isnt the light that lights the pixels still the backlight? But the pixels can dim I understand, so even if the backlight is flicker free, the pixels make it appear as flicker? I'm not sure what the nature of this flicker is - it may as well be pixel inversion mentioned by @KM . I'll have to read how LED / LCD screens are built, but I believe that there might be set of overall LED lights behind whole screen, but pixels may also have their own brightness, or control how much light they let through by FRC, dithering or other ways. martin -is it software controlled? I'd like to test it - guys in other comments suggested checking different OSes or tools like Ditherig. I also know @JTL has been working on some dithering disabling options. I hope it's software-controlled as it would mean that the technology itself isn't broken, just needs a good driver, we could then count on creation of an optional driver that stops flickering sacrificing color quality on screens. martin -if it is, we need to send this to a few people, if you dont wanna do it I can do it - mostly Daniel Georgiev, who programmed iris and could be capable to use this information to program a cancellation of this effect into his software too. I'd be glad to send this and other findings to our known contacts that may at least tell us if it's dithering, FRC or other stuff, so we know what causes our issues. I'm not sure if it's 100% accurate, it may be another wrong path, but at least correlation between screens that are usable for me and visibility of flicker in tests is promising.

martin could be capable to use this information to program a cancellation of this effect into his software too. Maybe, maybe not. It's either controlled by the GPU dirver or firmware, which iris works "above" so any workarounds would reduce visual quality further compared to a lower-level fix. What I think might be of interest is testing my hypothetical dithering fix after I get it working with a microscope or capture card, etc.

Just a small update - I've just tried decreasing the camera brightness in phone's settings and it seems to be able to see whole pixels behavior, even on high brightness of target screen, so that's a good sign as it should allow for tests on the whole spectrum. I've quickly checked Mac screen with Windows 10 again and while on slowmo it shows flicker, when observing it with bare eye there seems to be another layer of dithering where pixels change their colors slower. It's like fading in and out between two shades every 0.5-1s. It might be the same thing, but perhaps there is both some PWM-like behavior on subpixel level which gives flicker in slowmo and another - dithering-like that can be observed without 120fps. I'll have to check if Ditherig can stop this slow dithering and if it's visible the same way when I record it in standard, (non-slowmo) mode.

Screens under microscope in slowmo (dithering / FRC tests)

martin

andc Could you please do one subjective test for me please? When you are looking through the microscope at the display thats causing you issues (flickering subpixels), if you keep looking longer just through the microscope, does it start giving you issues or not? If not, then it would prove that the flicker is not the cause, but the eye fixation is - when there is such a clear outline as individual pixels to focus on, the problem could disappear no matter the flickering. Without the scope then, the eye fixation could be more complicated and thus the issue comes back. Please let me know.

andc

martin
It might be hard to test - since I don't use this Mac on a daily basis I got a little bit immune to this screen, at least on W10, ie. when I used it a lot even 5 minutes could trigger issues, now I can stand 1-2 hours, this doesn't seem to cause long time effects (broken sight for one day, etc.). It was a surprise when I started doing these tests, rendering videos, etc. Maybe it's new W10 which is somehow better than older updates.

So I think it would probably tire my eyes faster by looking through the scope, in a physical way. It's a single lens microscope, so different view in each eye could be problematic too.

Anyway, do you want to check if issues start to appear due to light coming from the screen, not the focusing on it? Maybe running this notebook as a background "lamp" on a flickering shade and trying to see if I get tired eyes without looking at the screen directly after 30 minutes would be a good test then.

martin

andc Yes, that is the point. Im trying to differentiate between the issue possibly caused by flicker and issue caused by eye fixation. It can also be both - flicker plus small pixels and aliasing result in bad eye fixation, while under the scope, the fixation is easy due to clear outlines of pixels being visible. It would also prove (in your case) the dependency on one vs. both eyes as a factor.

hpst

martin Flickering/movement of some sort seems a logical culprit...I don't believe aliasing etc is though since none of us are bothered by print...and if you zoom in on ink on paper it's fuzzy and blotchy so rules out the idea that only sharp and fine edges are focusable and anti-aliased/smoothed fonts look similar to printed ink zoomed in. It makes more sense that its the movement bothering us rather than the absolute clarity.

martin

hpst Youre trying to find one reason behind it all and thats the biggest obstrucion on solving it. I am bothered by aliasing (aliased subtitles in bsplayer gave me headache, turned it off and voila, its gone), I am bothered by PWM (tested with oscope on my LED ASUS work monitor, PWM below 100% brightness is painful, full brightness and Im using it for very long time now). It can also be bluelight, it can also be dithering. And the reason it can be so many things is because in my opinion, each of them disturb vision and especially binocular vision.
User erwin has just proven with his case that its both - new tech does something (many things) differently, and we might all have certain kind (maybe not all the same kind) of visual problems ( i do, getting treated now). Its a combination of things, thats why its so elusive. It has to be considered screen by screen, device by device. Unfortunately. And that is because the vision we all have (or lack) also plays a major role.

Also paper is way more textured than any screen ever will. Ink might be fuzzy, but the canvas is not and its in the same visual distance. Also some people reported that putting very textured matte cover on their phone screens solved it. Movement and fuzzy fonts might appear the same to an eye, both are hard to fixate upon.

hpst

martin I think the "that's the biggest obstruction" comment was unfair. I do believe there IS a primary technological root cause. I know you don't agree. Too many of us have the same symptoms with the same types of tech for it to be "everyone is different". It is impossible that each device has some qualititatively different cause and is far more logical to thing there is a primary root insult. I also disagree erwin's case PROVES what you claim. Erwin's relief could have been coincidental, because of or in spite of the meds, or he just got used to the new display as some people exerience initial strain and then relief. It doesn't prove anything.

I think we need to do practical things like shut off dithering and see if that helps. It's a clear and objective change and test. We can avoid PWM, block blue light, not use LED etc and those have proven not at all a common culprit. I think by claiming its 7 different factors and different in each person all you do is muddy things to the point you can't ever be sure what is or isn't working. How many times have you seen peolpe post "cured!" with some claim its a panel type or PWM or whatever, only to see them later say it is back? Nearly every time it is like that. I have had those eureka moments many times myself. I have not once seen more than ONE person say "I fixed my convergence, eliminated PWM, and use only CCFL and everything is fine now for good. I firmly believe that's because we haven't found the cause...once we do you will see MOST people noting relief in the same way people in an office stop having breathing problems once mold is removed etc. There is a noxious stimulus and we haven't found it.

martin

hpst I mean for you it might be obstructive. If you manage to find one single reason behind all of these (apart from a health issue/eye problem, that would render all these issues nonexistent, which I hope for with my eye therapy), so if you find one technological culprit that applies to all, Ill congratulate you and will be very happy.
However from my experience so far it seems its multifactorial.

alarmatwork

Can you please make test on iPad as well... It supposed to have Retina display as well, but my eyes are cool for looking it for hours... But MacBook Pro 2018 takes only minutes for the first symptoms to appear. Just to understand the difference.

tfouto

I made a USB video with a cheap microscope.

On Sony XZ 2 not on max brightness there is lots of ficker. Dont know how reliable is the camera.

Can anyone watch the video and see if it causes any strain symptoms?
Watching the Sony Video on Computer seems to trigger me the symptoms. Have to rewatch it later.
Be careful watching the following video, too much flickering:

Sony Xz 2: https://1drv.ms/v/s!Ai2kKt-CrSGog4lbfMO-b1Gfo0iNqA
Original file: https://1drv.ms/u/s!Ai2kKt-CrSGog4lcKNFY32S7Z0H0lw
For some reason when converting to mp4 didn't convert it to the end.

On HTC One at máx brightness, there seem to be background noise probably seems on backlight.

HTC One: https://1drv.ms/v/s!Ai2kKt-CrSGog4la7Kj7wzV3pRnu9Q

Btw usually dithering works at what frequencies?

tfouto

Andc, it's really amazing this thread. I have watch the first video. It seems i feel the neurological symptoms of watching this video, led's flickering on my 27'' monitor. Crazy.

Do you have the HTC 10 video? I am considering buying. BTW, do what is the microscope? Is it expensive? I might buy one.

Btw i bought a small filter 450nm, it only lets passes blue light. There's so much blue light everywhere. Even in your video of red, and green led's only there was so much blue light coming from the filter. THis means that this devices acomplish this color with lots of blue. There is no other way since the spectrum is has so much blue in it. A huge spike.

https://www.peauproductions.com/products/blue-light-filter

tfouto

andc What's the model of the microscope you use?

andc

tfouto

I'm sorry, I missed your previous comment. I captured HTC 10 screen only with Iphone 8+ camera, but it seems to miss any flicker, probably due to some kind of algorithm in iOS to make videos more fluid, I couldn't make it reveal the same things I observed while using HTC 10 to capture these videos. I'll probably buy another HTC 10 in coming months once battery in mine dies (it's at 60% capacity at the moment), so it might be interesting to capture both devices one with another.

Regarding microscope - it's an old soviet semi-toy microscope called "Naturalist" - exactly this one: https://www.ebay.ie/itm/Microscope-NATURALIST-Vintage-PLASTIC-CHILDREN-TOY-USSR-Box-and-Accessories/123554698744?hash=item1cc46f15f8:g:9x0AAOSwMNxXanjk:rk:12:pf:0
Unlike most current toy microscope this actually works and allows me to get decent zoom-in to see individual pixels.

I think blue light will be on every recording since it's present in gray tones and camera capture can be a little bit different from the source due to encoding / compression. I think some minor flickers on my videos are probably compression artifacts, but there is definitely an obvious alternating flicker pattern clearly visible too.

hector

nice findings! thanks for your great work. indeed i´ve got eyestrain when using htc10 and iphone8, but also on ipad 10.5 2017. But i will now stay away from displays with FRC!

displays are getting cheaper and cheaper, you have discovered another reason. Don´t buy this sh*t.
I´ve already send Apple several mails regarding their cheap displays...no answer yet.

martin

Weve done similar tests now under a powerful industrial microscope with some extra tools to get rid of intereferences like PWM and screen refresh rate. I can confirm some of the findings here - iphone 4s which was good for me showed no subpixel flicker at all. Iphone 7 shows quite a strong flickering. I also noticed flicker in apps, where the app layout and fonts doesnt flicker, but what the app loads (website browser) does. We will record our findings and eventually make an article and post it here. It is possible that PWM is a separate flicker from subpixel flickering (temporal rendering, dithering) and screen refresh rate. If these frequencies meet in a weird way, it produces flicker of way lower frequencies than what is safe. Also those may not be a whole screen occurence, but localized in different parts of the screen.
@andc Could you write me an email specifying what exactly you did in those tests? mjanas555 (at) gmail (dot) com

diop

martin This matches the info on the patent I posted a while back. So it’s somehow creating a ‘pseudo 15hz’ flicker or something similar. Anybody setting their monitor to even 24hz will tell you how horrid that is.

It would be good if this research could expand to PC’s - use a known good GPU/PC/Monitor but load good and bad OS/Driver combinations to see if a trend emerges.

Surely the labs that make this technology would have inspected everything at a microscopic level before mass manufacture? This is to assume it is the panel at fault, which I still largely believe it isn’t.

GregAtkinson

martin Were you able to post your findings from the powerful industrial microscope? I'm tempted to purchase a slow motion camera to see if I can identify why some displays work well and others do not.

kammerer

KM
There are a bunch of tests to determine pixel invertion pattern in http://www.techmind.org/lcd/
Looks like it's good idea to compare invertion pattern on good/bad OS/display. Look like I have different invertion pattern on same display with different OS and cards: https://gitlab.freedesktop.org/drm/amd/issues/977#note_409979

martin

diop Yes it does and no I dont expect they would. It seems to be a somewhat unfortunate combination of features that span monitor, OS and driver issues. It might even be a coincidence of the industry, where the left hand doesnt know what the right is doing. Seeing some industrial cases in the past years (c8 pollution by dupont for example), I higly doubnt anyone checks anything, yet on microscopic level. Or that they care even when they know to do anything about it if its not cost effective. This issue is not life threatening (unless you wanna suicide from it, which I dont blame you if you do), so its easy to disregard on industrial level compared to what other horrid stuff came from large industries.

diop

martin It is not life threatening, but I would say it is certainly life limiting. I still think the industry have simply mass-imposed dithering (at driver level/hardware level) in new tech as a shortcut to avoid producing expensive 8bpc+ monitors, and to hide any signs that the display is of a lower quality. It wouldn’t surprise me if our expensive phones are using sub-par or older display tech, which relies on dithering to keep the perceived colours 99% perfect across the board. In many ways it could be said that dithering is an RGB standard in effect as it almost guarantees the same perceived color range as 10bit, minus the cost.

What I don’t understand after all this time is why there isn’t an off switch. Even when directly speaking to graphics developers, they either don’t know or don’t care about it. The freedesktop Linux post on another thread has been open for weeks, I simply want a black and white answer to.

What dithering is currently used on consumer devices? Can it be disabled? Somebody had to have created this pixel movement therefore it can be disabled in just a few lines of code.

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