Finally, I have found next logic: there could be 2 main factors:
- OS dithering
- Screen dithering
In Honor 2023 7840hs laptop, I get a little reduced strain ( to be honest, I spend only 3 days, so… ) - I think coz I installed safe w10 1809 build and felt only screen discomfort
From august 2023, I tested 3 laptops:
- Asus zephyrus 2022 g16 i7 12700h rtx4060 ( NE160WUM-NX2 panel )
- Lenovo Thinkbook G6+ 2024 Ultra 7 155h with Intel Arc ( MNG007DA1-J panel )
- Honor Magicbook 16pro 2023 7840hs ( NV160WUM-NH3 panel )
They all 16", FULLHD, 2.5k, FULLHD+ resolutions, 8 or 10 bit, AMD or Intel based, iGPU or dGPU ( zephyrus ), 60hz only or 120 or 165
All makes me pain in temples, as more I used them, even in safe w10 1809 build (dither free). But in last Honor I get a little reduced feeling, because old win10 1809 works nice with it ( I excluded the OS factor)
Opple4 shows no low-freq screen flickering in all of them
But
Have a look those 2 interesting documents:
https://patentimages.storage.googleapis.com/1a/35/cd/35c781bb450a21/US20020147861A1.pdf
https://www.tdcommons.org/cgi/viewcontent.cgi?article=4505&context=dpubs_series ( thanx to SunnyCove from 4pda webforums for share it )
2nd one decribes, how build in T-CON panel chip can work in 2 modes: PWM and AUX (dithering). This is what I mention when talked about OPPO 2019 research ( https://www.gizchina.com/2019/04/03/oppo-announces-dc-like-dimming-feature-for-coloros/ ), how do they reduce brightness mixing gray layer
What I got from 2nd document, is fully digital brightness control. Thats can answer why all laptops have non-linear brightness control ( medium value is in 75..80% range ). And perhaps, manufactures called this method DC-dimming. If I got idea right, T-CON chip remap ( compress from max 255 brightness to 128 for example) image brightness accroding to user selected level of brightness and use dithering to smooth artifacts
The major findings - is T-CON can dither image to reduce brightness
If modern laptop have hybrid T-CON, via driver, we can set his work to oldschool PWM instead of AUX
If modern laptop have only AUX (or similar name) panel, we can change nothing at all
This findings can answer why:
- Even in DC-dimming screens, when we reduce brightness, we still feel power of brightness (LED still shine in full power) - some users reported looking at screen as looking at bright metal welding
- Old devices or old drivers do not support AUX dimming, when you update win10/11 to last one, you get only windows dithering (without additional screen dithering)
- This screen changes started in 2020+ years