Using Eink Monitors To Detect Temporal Dithering

photon78s

I'm wondering if this approach can also be used to reveal if certain apps (to avoid) still trigger some form of dithering or other artifacts. Related would be this post: https://www.reddit.com/r/PWM_Sensitive/comments/17asicl/some_specific_apps_are_lowering_your_phone/

jordan

photon78s So I viewed the reddit app with my mudita kompakt eink phone but did not see anything flickering. I did see a follow up post from him and it looks to be something in iOS at least that app devs have access to. I think its backlight related and not pixel related. https://www.reddit.com/r/PWM_Sensitive/comments/1lenpfy/if_not_for_pwm_sensitivity_why_are_our_eyes_still/

WhisperingWind

Thanks I will mess with that sometime soon and see if I can figure it out. I think spatial regardless is going to be much less of an issue than temporal. Do you know if the worst case setup is spatial only, not temporal?

WhisperingWind

jordan

Do you happen to know the command for forcing dithering off in Linux?

I can only recommend AMD/UMR for working with the register responsible for dithering on AMD graphics cards: https://gitlab.freedesktop.org/tomstdenis/umr

You’ll have to build it from source. It includes a GUI tool for managing the register contents.

umr can be run in GUI mode using

$ umr --gui

The value of the bit responsible for dithering in Linux Mint Cinnamon 22.1 (v.6.8.0): 0x00008900.

The FMT_BIT_DEPTH_CONTROL.FMT_SPATIAL_DITHER_EN bit is set in Linux.

As I understand it, SPATIAL DITHER is enabled on Linux; you need to clear this bit using the AMD/UMR GUI tool. It may be necessary to clear some other bits as well; you’ll need to look at the contents of the register.

I don’t have a Linux machine handy right now, so I can’t provide detailed guidance.

WhisperingWind

jordan

I took the question to mean: have I ever come across a case where spatial dithering was worse than temporal? 🙂

I haven’t used a setup like that. For me, temporal dithering is always worse than spatial. I’ve never had eye strain from spatial dithering (but I always try to disable dithering completely), but that’s just my experience - others may react differently.

photon78s

jordan

For those running certain game engine related applications:

White pixel flickering artifacts with "DitherFade" material layer #1388

https://github.com/CesiumGS/cesium-unreal/issues/1388

This would be an example of application related features.

Could this method help with investigating things like this?:

https://ledstrain.org/d/1064-google-chrome-temporal-dithering/34

jordan

WhisperingWind Oh I mean do you know if amd radeon specifically can use temporal dithering worst case or does the driver only use spatial if needed?

BTW here is a video I recorded of win10 1809 with a 1660 super. I show using the color control app to disable and enable GPU dithering. You can see the Eink screen does expose GPU dithering when I turn it on when I use the non bugged display mode. https://www.youtube.com/watch?v=Moq-LLhw3Nc
If anyone wants me to try the additional display modes on the boox I can try those, it requires the mira win/linux program. The ones I showed in the video are the preset ones in monitor settings. I can also try the dasung 253 too upon request.

WhisperingWind

jordan

Oh I mean do you know if amd radeon specifically can use temporal dithering worst case or does the driver only use spatial if needed?

I don’t have much experience with AMD GPUs. Previously, I used an AMD Radeon Pro 570 in a 2019 iMac; there was no temporal dithering on the GPU side because the monitor was 8-bit+FRC.

jordan

I tested low rgb range in nvidia control panel with the high quality eink mode and it triggers dithering but full range does not. I tried a GTX 1080 PNY blower card I found and it seems to operate the same as the 1660s in terms of dithering on my eink monitor.

jordan

photon78s Hmm thats odd I havent noticed any of that in any apps I use specifically. even latest FF seems ok.

WhisperingWind Gotcha okay. In cachyos with my eink monitor I get

❯ echo “Color Depth: $(sudo cat /sys/kernel/debug/dri/0000:03:00.0/crtc-0/amdgpu_current_bpc)”
echo “Colorspace: $(sudo cat /sys/kernel/debug/dri/0000:03:00.0/crtc-0/amdgpu_current_colorspace)”

Color Depth: Current: 8
Colorspace: srgb

but with a true 8 bit rlcd (eazeye 2.0) I get
Color Depth: Current: 12
Colorspace: BT709_YCC

So I definitely need to find a way to force 8 bit srgb on it before I test the monitor. This kinda verifies that even if any of us have a true 8 bit monitor, the edid can still advertise up to 12bit like im seeing here. UGH

FreeStar

Tests that don’t list the WDDM version aren’t telling the whole story. The same video driver on different Windows builds can end up using different WDDM versions, and Windows behaves differently depending on that.

If you’re running a 1660 Ti / Super, use the NVIDIA 419.17 driver. Before installing, strip out everything you don’t need from the installer with NVCleanstall. Remove the extra components (and HAGS) — it kills pointless background effects and usually improves MPO.

jordan

FreeStar The original tests I did were messed up due to a messed up display mode with my eink monitor. I actually didnt see dithering at all once I figured that out. I was able to manually enable dithering and saw it in windows but default settings it wasnt present. I think I was using the 451 driver. I think there still is something more going on with windows that isnt only dithering related. Just curious what windows version and gpu do you use? Seems 419.17 is your preference?

macsforme

I have also noticed that certain wallpapers seem to cause more flickering, specifically on macOS. The default High Sierra wallpaper was where I first started noticing this. The default Monterey wallpaper also exhibits harsh flickering in the gradients. I would not be surprised if the flickering from the wallpaper contributes to strain throughout the entire UI.

The old wallpaper showing a space photograph of the moon over the earth (from the High Sierra era) is one of the most comfortable macOS wallpapers for me. I am unsure whether there is a specific wallpaper characteristic that triggers the flickering (bit depth, HDR, etc.) versus simply the nature of what is depicted.

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