Hey - what is the best way to measure temporal dithering? Microsocope for phone? which one, where to get?
Products to try or avoid? PWM Flicker and Temporal Dithering Testing
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I use this: https://carson.com/product/mp-250-led-lighted-pocket-microscope/
I use 240 fps slow motion camera mode on my samsung s10+ but some newer phones can do higher fps which is good for testing the higher refresh rate screens.
You will be able to see pixel flicker from either pixel inversion and dithering or both. The problem is I have yet to find anything where the image is 100% stable.
I also would record at 100% backlight brightness to help factor out PWM and low video quality due to low light noise.
Just posting for reference of prior work on dithering (using capture card and videodiff software)
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I have 1809 running on the second hard drive of the 7i and install the latest studio driver from nvidia to enable 240 fps refresh rate (otherwise the panel is stuck at 64Hz). Thanks for the suggestion!
Laptop is set to discrete GPU, color control dithering disabled.
Difficult to say if this is any better at first glance both holistically and under the scope. I'm not able to get the full raw 240 fps video from the phone camera app just a slowed down version at 30 fps on playback. Still, I was expecting to see more flickering (filmed on the middle part of the lagrom gradient). If someone is watching the video, notice how when I move the camera so that the top left flickering pixels enter the center area, the pixels stops flashing? That is because their is less light captured there and the noise of the phone camera sensor is more visible which itself is a temporally flickering effect.
If you look at the video, I think it is slightly better. However as you know, the 240 fps refresh is the same framerate as the supposed slow mo mode of the samsung so I don't have the ideal testing gear. I briefly looked the video of it set to 60Hz refresh but it was flickering like usual in an alternating pattern (pixel inversion?). I haven't installed the secondary update, will let you know when I test with that.
Symptoms have improved a lot for me over the 60Hz setting I was using earlier last year. I don't get headaches or migraines, just some moderate eye strain over a last couple of weeks. But then I have been using it not as much. I still feel the internal panel is slightly less straining than the LG although both are huge improvements over the "10 bit" Eizo.
I haven't looked at the videos since I'm sensitive to flicker. Ohhh the manual update is a must because that's the build/update ver that is safe. Just the iso alone could be a problem till you update with that manual update. Theres no iso with the update pre installed unfortunately.
Gotcha I mean it doesn't sound terrible terrible. I just wonder if 1809 with manual update will be noticeable 
photon78s this was posted in the led eye strain telegram group. You can see how newer windows shimmers/flickers while 1809 doesn't. https://imgur.com/a/ogocBtt
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Interesting video. I'm now using the 1809 with the manual update installed. The build version is 17763.1098. Is this correct? All I can say is the somehow the maximum brightness is lower than on Win 11 making it seem calmer to me. Through the scope, it is see hard to tell if all I see is just noise flickering from the camera sensor or dithering or inversion (this might be a good sign). If you have testing 1809 to work on your other machines, then this is probably the way to go if/when you decide to test your 7i. Also, in appearance and performance, I turned everything off (adjust for best performance). On the lagrom gradient banding page, I see more banding.
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Game ready driver 537.34 - Sept 12 2023
https://www.nvidia.com/download/driverResults.aspx/211638/en-us
Studio 537.42 - Sept 21 2023
https://www.nvidia.com/download/driverResults.aspx/211716/en-us
I used their advanced search tool:
https://www.nvidia.com/download/find.aspx
A friend modified a GTX driver(even older) with rtx GPU hardware id in the past and it ran fine without ray tracing. Might be another option if you ever wanted to go that route for any testing haha.
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Thank you!
I installed 1809 with the update on the T480s (with B140QAN2.3 panel) and it has clearly visible banding. The Lagrom gradient even seems to animate the banding and then stop (minimizing and opening the browser would do that). However, under the microscope measuring the gradient, it is almost completely "stable" and clearly more stable than the 7i on 1809 (might be due to low max backlight brightness causing noise). Perhaps now I am seeing mostly noise + pixel inversion.
This is just a 60 Hz panel so this is even more interesting. The gpu is the outdated Intel UHD Graphics 620 not Iris Xe. Also the panel can get significantly brighter than the 7i running 1809 making recording have less camera sensor noise.
For the less flicker sensitive who want to check out videos (T480s 60Hz 1809 best case versus Legion 7i 60Hz Windows 1 23H2 worst case videos of a darker transition part of the lagrom gradient):
https://www.dropbox.com/scl/fo/adv3uvxm0tvi6hndxli2p/h?rlkey=kcsyjrq6p5bf6qprdco9gx4ed&dl=0
Tentatively, the 60Hz T480s running 1809 is similar to the 240Hz 7i running1809 and better than the 7i at 240Hz running 23H2. The worst flickering is with the 7i at 60Hz running the latest 23H2 update.
Btw the panel in 7i pro appears to be this. https://panelook.com/modeldetail.php?id=61681
It shows it as 10bit but I wonder if it's really 8+2frc which is why 60Hz seems to be dithering. Maybe 8bpc forced in Nvidia control panel would have different results under the microscope.
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Yes, the T480s running 1809 and not win 11 is similar to 1809 240Hz 7i. The T480s has supposedly crap AUO B140QAN02.3 panel I stated earlier, not the LG panel listed in the table which I don't have anymore to swap out and test.
My good news for the day: On the 7i using 1809 with BIOS set to dynamic and using intel graphics but with no intel driver installed using MS Basic Adapter at 64Hz refresh rate, I am seeing almost none of the typical slow alternating flicker which I thought was pixel inversion. The image under the scope is stable similar to using 1809 at 240 Hz but using discrete gpu. I cannot set screen refresh rate any higher than 64Hz with the basic MS driver. When I go back to 23H2 on the 7i and still using 60Hz panel refresh, I again see the slow alternating pattern of flicker even when I force 8 bit in discrete gpu in nvidia control panel or leave the bios set to dynamic and using iGPU.
This lead me to believe there is no extra dithering going on the software and gpu side and the output to the panel is 8 bit. With a 8 bit + FRC fake 10 bit panel as you found, this could be another safer alternative. Thanks again for suggesting 1809. Now I have to be careful not to break this setup. 
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wow that's great to hear!!!
Sorry just to clarify.. so these both are same results no dithering and safe? I seem to do better with higher Hz devices so if your saying 240hz is as safe as 64hz this is awesome!!
- Win 10 1809 ltsc, 7i dynamic GPU 64hz
- Win 10 1809 ltsc, 7i Nvidia GPU forced 240hz
3.
I'm glad this is working for you. Someone actually suggested 1809 ltsc to me so I'm glad to pass it along! The 7i panel says 10bit on panel look I was only wondering if it's really 8+2frc if you feel up to it, might be interesting to see results with nvidia set to 10bpc and see if 8 and 10 bit are the same under the micrscope..or if 10 bit dithers. If 10bit turns on dithering than we will know that the screen is 8+2frc and not truly 10bit.
Edit: not sure how to get the "3." Removed above, won't deleted so just ignore that! Must be a mobile bug lol
Btw make sure to block windows updates! This should do the trick. https://www.sordum.org/9470/windows-update-blocker-v1-8/
I am going to try this exact config on my Lenovo once my current flare up relaxes and when I know I don't have any events upcoming haha. This sounds so promising 
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For the 7i:
If you want to use 60Hz screen refresh, use 1809 with intel gpu only. Even under 1809 with latest Nvidia studio driver with 60Hz screen flickers a lot (this might be fixable with modified drivers).
If you want to use 240Hz screen refresh, 1809 with latest Nvidia studio driver still seems similar to 23H2 with the same Nvidia studio driver (high screen refresh masking my ability to measure dither correctly). So you may not gain much with 1809. I will take a break from this testing lol and try those older Nvidia drivers later.
Using the 4080, I cannot tell the difference between 10 bit versus 8 bit on 23H2 or 1809. I think the latest Nvidia driver forces some kind of dithering anyway. Update: With 23H2 at 240Hz, it is also difficult to tell the difference between discrete mode or dynamic mode. Later, I would like to see if I could get 240Hz working in 1809 using just Intel iGPU.