Products to try or avoid? PWM Flicker and Temporal Dithering Testing
Is the view here that 8 bit + FRC is good enough and that is not going to change soon and we can label it as 10 bit because most will not know the difference?
photon78s ugh that's so frustrating. They are silently hurting us all even those who aren't on this forum. I'm sure so much people are affected and have no clue it's the screen. Probably not going to change until other company's start selling actual true 10bit or until people take legal actions.
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And choosing still not ideal or mature alternatives which I only know of RLCD, E-Ink, and what else (besides finding old tech monitors on used market)? Connecting monitors with older displaylink drivers to disable dithering?
https://www.synaptics.com/products/displaylink-graphics/downloads/windows
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https://safescreens.org/smartphones-and-social-media-harms/
They do mention eye damage and "digital eye strain" but still with myopic focus on blue light issues. Might be useful to know this at a later point.
I also don't think this will remain a "first world" problem for much longer. See adoption trends of smartphones for example. However, I don't know who is collecting rigorous data specific to health and screen technology issues.
Other intiatives:
https://www.change.org/p/apple-add-accessibility-options-to-reduce-eye-strain-and-support-vision-disability-sufferers
Research papers:
A Comparison of Seven Visual Fatigue Assessment Techniques In Three Data-Acquisition VDT Tasks
https://journals.sagepub.com/doi/abs/10.1518/001872098779649247
They mention "adaptive displays" in response to flicker sensitivity changes in people over time and "workload".
Digital eye strain: prevalence, measurement and amelioration
Video display terminal use and dry eye: preventive measures and future perspectives
https://onlinelibrary.wiley.com/doi/full/10.1111/aos.15105
"Video display terminal (VDT) use reduces blink rates and increases incomplete blinks, leading to tear film instability and ocular inflammation, promoting DED."
Working in the Metaverse: What Are the Risks? A Rapid Review of the Literature
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4731115
Just showing flicker have effects positive or negative.
Gamma frequency sensory stimulation in mild probable Alzheimer’s dementia patients: Results of feasibility and pilot studies
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0278412
Recently, we discovered that non-invasive entrainment of gamma frequency oscillations using light flickering at 40Hz (Gamma ENtrainment Using Sensory stimuli, GENUS) reduced amyloid load and induced glial response in the visual cortex of AD model mice, effectively attenuating AD-related pathology
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I don't know about the dell docks but it is used here:
https://ledstrain.org/d/2561-poly-studio-p21-monitor-with-displaylink-driver/2
The OWC adapter didn't work for me it terms of getting rid of dithering but it might be worth trying again using older drivers.
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You are right about linux mint. I connected the T480s via hdmi to the LG and I can't see dithering at least with my scope and camera. The monitor is only running at 30hz so if temporal dithering is occuring, I should be able to see it with the high speed camera easily. However, using a usb-c to displayport cable still has dithering. I am very happy with being able to use the LG even if not at high refresh rate. The hdmi cable I am using is the one that came with the LG monitor (it says 8k 60hz on s only running at 30hz so if temporal dithering is occuring, I should be able to see it with the high speed camera easily or even with normal speed camera (half the refresh rate dither). However, usiUpdate: I do see some very high frequency pixel flicker in slow motion video but it is clearly different than when I test this monitor with the usb-c to display port cable. The HDMI output on the T480s is also bandwidth limited which relates with discoveries in the the mac stillcolor discussion.
ng a usb-c to displayport cable still has dithering. I am very happy with being able to use the LG even if not at high refrethe cable). My T480s only has Intel UHD Graphics 620. It does not have the Nvidia MX150 discrete gpu as some other versions do. monitor
Also, I discovered my Nikon camera has hdmi out that also does not seem to cause dithering on the LG monitor which is 8 bit + FRC. The Nikon's output sets the monitor at 30hz. Again, I could not find anything with the scope unlike Win 11 at 60hz on the 7i. I was viewing smintome photos, and it was the first time in a while that the photos looked "stable".
Update: I still see some very high frequency pixel flicker in slow motion video but it is clearly different than when I test this monitor with the usb-c to display port cable. The HDMI output on the T480s is also bandwidth limited which relates with discoveries in the the mac stillcolor discussion.
photon78s oh wow that's great! I'm almost thinking Linux might end up being the best long term solution. There's actually a way to get displays to support 24hz when they don't by default, Maybe that's the best way to test for dither if it happens at the half of refresh rate. I think low Hz 10-15hz could cause photosensitive epilepsy in people that have it btw.
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I think I've disabled or modified the dithering at one level as with @aiaf with using bandwidth limited hdmi port or cable to a modern and demanding 4k monitor and what I'm still seeing is some kind of pixel inversion or similar (TCON generated dithering flicker?) on the LG. The still existing flicker is still fast when played back in slow motion so it is not at low 15hz (half refresh rate of 30hz). Using the computer, the mouse cursor lags as expected for 30hz refresh rate.
The only way to know health wise is to test for yourself which type of pixel flicker is more comfortable. Even with 100% no dithering, generated by the computer or monitor, you still have to deal with pixel inversion unless you go OLED or other types with all their own different set of limitations and issues.
https://www.reddit.com/r/thinkpad/comments/q13awt/t480s_4k_over_hdmi_or_usbc_or_thunderbolt/?rdt=50463
Yes, the T480s hdmi output is limited so one could use it for positive effect.
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T480s HDMI 1.4b cannot do 10bit?
https://www.reddit.com/r/Monitors/comments/d20vcn/hdmi_14_10bit_color_and_1440p_resolution/
https://uniaccessories.com/blogs/blog/hdmi-1-4-vs-2-0-what-is-the-major-difference
https://www.hdmi.org/spec/hdmi1_4b
https://www.electronics-notes.com/articles/audio-video/hdmi/hdmi-versions.php
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T480s -> LG monitor banding (linux mint, hdmi 1.4b connection)
https://ibb.co/CtxGm65 (not screenshot, taken with phone camera so ignore the moire)
Now same except using high bandwidth usb-c to displayport cable (32.4Gbps, 8k/60hz)
Current list of pixel flicker observations (encompassing dithering and/or inversion or other artifacts):
- Pixel inversion is dependent on display refresh rate (1/2 refresh rate?).
- A display's pixel flicker may change over time possibly due to temperature or other factors.
- Some pixels flicker in sync to computer coil whine when a power hungry usb device is plugged in. The flickering stops when the usb device is removed.
- A single pixel may flicker at a different rate compared with neighbors (what is this artifact?)
- Camera sensor noise and noise reduction algorithm artifacts may be confused with pixel flicker at low display brightness.
Updated tbd by findings…
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About pixel inversion:
https://display-corner.epfl.ch/index.php/LCD_dynamics
The open/close state of a (sub-)pixel cell is controlled by a voltage, where the amount of light being blocked by the cell only depends on the absolute voltage but is independent of the voltage polarity. However, the liquid crystal fluid in the cell actually degrades if the mean voltage is different from zero, which is why the voltage polarity has to be inverted at a high enough frequency. In a monitor, the polarity is inverted at the monitor's refresh frequency. It appears to be technically difficult though to meet exactly the same absolute voltage levels at both polarities, even for static image content. Any residual difference in absolute voltages causes an according difference in the cell states and, thus, in pixel luminance. These luminance fluctuations might be perceived as an according pixel flickering at half the refresh frequency. In order to make such flickering less apparent, both polarities are used at the same time but for different sub-pixels, so that potential differences can average out across space (i.e., across adjacent sub-pixels) and over time (i.e., over refresh cycles). Because the pattern of how polarities are distributed across sub-pixels is very regular, pixel-inversion artifacts can still become quite obvious, especially if the temporal averaging is compromised by eye movements of certain velocities, which makes the spatial polarity distribution pattern become more apparent for short periods of time. Pixel-inversion artifacts, or more generally, voltage stability artifacts, can also surface in other forms, like color shifts or cross-talk within pixel rows or columns. These artifacts possibly show up under only very specific circumstances, which makes testing and quantification difficult. Although high pixel densities and high refresh rates both can help in hiding pixel-inversion artifacts, those features also make it technically more challenging to avoid such artifacts in the first place.
So if your eye movements are not at the "certain velocities", then will this help with avoiding eyestrain?
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https://www.ncbi.nlm.nih.gov/books/NBK10991/
Types of eye movements.
saccades, smooth pursuit movements, vergence movements, and vestibulo-ocular movements
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Eizo CG2700X Monitor Opple4 Results at 27% brightness:
What really flickers are the front panel button indicator LEDs which thankfully can be turned off.
It is beginning to look like this is a true 10-bit monitor not 8bit + FRC. More later…
photon78s Someone recently posted a video claiming there are issues with the backlight/illumination of the CG2700X. As I haven't got my hands on a CG2700X (yet), do you have any comment?
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I see some slight uniformity differences but not as bad as the video. This is very concerning considering the reputation and obvious high cost. I think I can live with it but I remember the last Eizo I tested CS2740 was slightly more uniform. Actually, it was the first thing that impressed me about that "cheaper" Eizo.
On the positive side, I am testing with my 7i and T480s first using bandwidth limited High Speed with Ethernet hdmi cable like what @aiaf was using and the pixel flicker under scope compared with the LG is night and day difference. I'm guessing that the slight flicker I see on the Eizo is just due to pixel inversion at 30hz (1/2 refresh rate) or with some OS/Gpu generated dithering but it is much less than the LG. I assume this difference is exactly due to the lack of FRC on the Eizo.
To be consistent both monitors were tested at 60hz (the LG can do 144hz but that distorts fair comparison). The Eizo can tell me in the menu that my signal is 10 bit when I use a 30Gbps usb-c to displayport cable but it does not display anything when using this old HDMI cable. For this test, the 7i was running Win 11 on Nvidia GPU with I think dithers and the T480s was running linux mint.
Brightness is indicated in the menu using candela per square meter instead of percentage brightness so the 27% is roughly 150 cd/m2 out 550 cd/m2 (max brightness).
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Make sure you have a good return policy if you do decide. Like the CS2740, I don't like the matte screen texture (its ok but I prefer slightly more "smoothness" but not fully glossy). Wish there were more affordable true 10-bit non FRC displays. The problem I have with the Apple XDR other than the even higher cost is the miniLED blooming and possible fatigue from just that backlight tech.
Uniformity picture. Not too too bad (ignore the bright spot in the center which is a reflection)