Screens under microscope in slowmo (dithering / FRC tests)
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JTL A good oscilloscope can do that.
I know it can, but camera would show what really happens, especially how dithering is made on individual pixels level, whether it happens on all the brightness levels, etc.
cont-temp 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.
I checked various color profiles on MacOS yesterday (around 8 of them including Color LCD, Adobe RGB, Universal RGB, sRGB, Display P3). Each of them flickers on static deep-green color (rgb(0,50,0)) - some are better, some are worse, but differences probably come from the actual representation of this color on different profiles - it ranges from standard green (for brighter profiles) to almost black (for darker ones). Turning off font-aliasing didn't stop the flicker. Running Night Shift didn't change it too, although results were a little bit different than I expected - there was no added red subpixel component visible this time, maybe it's too subtle for camera, but I'll have to recheck it.
I also made a test with shades of gray getting down from 255 (white) to 0 (black) which shows obvious flickering at lower levels.
Another test I tried is checking how lagom's pixel inversion examples (http://www.lagom.nl/lcd-test/inversion.php) look under the microscope. There weren't any anomalies, they were shown as standard static pixels in different configuration.
I'll upload shades of gray and lagom's videos later, just for reference, although they don't seem to reveal too much.
Next step is checking browsers - Firefox Quantum vs. Safari vs. Chrome on MacOS - maybe some differences in font rendering will be easy to be spotted if one of them is using non-standard shading on the edges.
Edit:
Here are 2 videos with grayscale and Lagom.nl tests:
I've checked various webpages in Firefox Quantum (62.0.3), Chrome (69.0.3497.100) and Edge on Win 10/Macbook setup and haven't seen major differences between them so far. I'll try to write another script that will scroll the same way through some example text in different fonts so we can compare them 1-1 between these browsers, current browsing video is too chaotic to be reliable comparison input.
What's interesting is the fact that every font seems to use some antialiasing stuff, i.e. it isn't just black, but also has some shades on the edges, the bigger the font the wider this shade is. As can be spotted on previous videos - shades equal dithering. And this dithering happens exactly where our eyes try to get focus (at the edges of characters). It may mean that our eye strain may be a result of focusing exactly on things that are constantly changing. I didn't think this shading will be happenning in such extent on retina screen which is quite sharp, but it does.
andc I've checked various webpages in Firefox Quantum
Try downgrading to 57 and deleting and creating a fresh Firefox profile. i'd be curious of your results.
https://www.howtogeek.com/255587/how-to-find-your-firefox-profile-folder-on-windows-mac-and-linux/
https://support.mozilla.org/en-US/kb/install-older-version-of-firefox
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@andc when you started your research with your MBP 13'' 2015 which OSX version were you using?
I noticed that I get migraine like symptoms when using OSX 10.13.5 and up (including Mojave). When I reverted the graphics driver to the one in OSX 10.13.4 it got way better (even on Mojave). The blue light is still an issue, but hey, no migraine
Edit: Ok, Apple does something on 10.13.6 and up that cannot be fixed by reverting the graphics driver. So I need to go back to 10.13.4 (or 10.14.5 with old driver) to get my head straight again...).
Here is another video: rendering of fonts on W10/Macbook Pro in different browsers: Chrome, Edge, Firefox in current versions (I'll downgrade Firefox to see if it differs later).
https://vimeo.com/294862076I ran custom script that scrolled through sets of "S" letters (since it has most curves, so most potential antialiasing would happen) in different fonts, boldness levels, with antialiasing set to on / off, etc.
Results may not look groundbreaking, but you should clearly see dithering on the edges where antialiasing (i.e. shading on subpixel level) happens. Actually this is not so big as I saw before on some pages - probably there are worse fonts than the standard ones I used (Courier, Times New Roman, Arial, Verdana, etc.). Also worth noting is the fact that this screen is retina, i.e. pixels are really small, so the same fonts should use more dithering on screens with lower resolution.
Next test I'll be preparing is running the same "S" letters in different shades of gray. I've seen that lots of sites (even Ledstrain) use some deep gray instead of black for the color of their main font. So it's likely to dither, although it seems to be black.
I think we may start sharing these videos with more experienced guys (i.e. tech, industry contacts) as @martin suggested since further tests will not be likely to reveal more details, the only big step may be finding a setup (OS, driver) that doesn't dither on the screen that flickers usually. I'll be testing early W10 installation soon, but I don't have high hopes.
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Another video with fonts in different shades of gray (latest Chrome on Win 10 / Macbook Pro 13):
https://vimeo.com/294902061Shades range from black - the first one - #000 to light gray - #bbb. Flickering is visible at first only on edges, but when font becomes more gray whole its area starts to flicker. If you're wondering how given color looks like, here is an example: http://jsfiddle.net/scaLtk8u/1/ - see bottom right part.
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I need to check one more thing - iterate over ~20 shades surrounding the ones that usually flicker.
My idea is - if dithering could be stopped with decreased color depth (i.e. resigining from more accurate colors), there should be at least one shade close to dithering ones with which they can be substituted. If none of them is stable then I don't see a chance of finding non-flickering setup with such screen - each deep red, green, or blue, as well as their combinations will flicker, even on 16 colors display.
I initially thought that displays use dithering to fill gaps between supported colors (which should be solid), but it looks rather like PWM on subpixel level, where every darker color causes flickering.
The worst case scenario is that such screens are actually not 6, 8 or 10 bit, but 1-bit, i.e. capable of displaying only max brightness (pure color) and min brightness (black) as solid dot, and everything inbetween is simply subpixel flickering, same as PWM can be observed on many displays.
Edit: I checked the screen again - my script went through around 30 subsequent shades - each of them flickered, there's no stable phase, so every darker color is subject to dithering. I tried also different settings of ditherig.exe, but it didn't help as well in any case.
A strange observation was behavior of Chrome, rather an HTML bug than something important for screen itself:
on my testpage I have an info panel with white background. When it's present on screen, Chrome shows some kind of banding-like artifact - top 25% of screen has different shade then the rest on specific range of background color (around rgb(0,30,0)). I'm not sure where it comes from, but neither Firefox nor Edge behave the same way. <body> CSS consists just of background color and it isn't uniform. That's just another sign that with Google stuff you may never be sure recently
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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.
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.
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.
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.
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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.
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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.
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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.
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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.
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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?
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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.