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Sensitivity to PWM = sensitivity to DyAc?

Ask about motion blur reduction in gaming monitors. Includes ULMB (Ultra Low Motion Blur), NVIDIA LightBoost, ASUS ELMB, BenQ/Zowie DyAc, Turbo240, ToastyX Strobelight, etc.

Sensitivity to PWM = sensitivity to DyAc?

Postby blurbustingbunny » 07 Apr 2019, 15:35

I cannot use most phones or laptops with PWM (although it seems to vary a bit...some implementations of PWM seem less harsh than others)

Would I be able to use monitors with DyAc enabled? Or would they give me the same symptoms?
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Re: Sensitivity to PWM = sensitivity to DyAc?

Postby Chief Blur Buster » 07 Apr 2019, 20:27

Anecdotally over the years, with many coming to us about display ergonomic quirks, it's a more complicated question than expected. It depends on if your PWM sensitivity is from PWM artifacts or from PWM flicker itself.

Sensitivity to PWM flicker
That's the direct sensitivity to flicker itself.
Strobe-based blur reduction will probably bother you.

Sensitivity to PWM artifacts
Also often the same kind of sensitivity to stroboscopic artifacts from PWM lamp dimming (e.g. LED bulbs that flicker).
Strobe-based blur reduction avoid these artifacts for eye-tracking situations, as one-PWM-pulse-per-refresh.
So you might have less strain from this, and even tolerate it.
Image

Motion Blur Reduction is defacto a special precision 1-pulse-per-refresh PWM
Motion blur reduction can be a more eye-friendly PWM but it won't be friendly to everyone who has a PWM sensitivity.
Unfortunately there's no way to easily tell if motion blur reduction will help or hurt your eyes. but the good news is that display motion blur reduction is a feature that can be toggled ON/OFF.

Another way to reduce motion blur is simply sheer Hz (flickerfree). The use of flickerfree 240fps at 240Hz has one-quarter the display motion blur of flickerfree 60fps at 60Hz. (This is known as motion blur from the sample-and-hold effect).
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Re: Sensitivity to PWM = sensitivity to DyAc?

Postby blurbustingbunny » 08 Apr 2019, 14:39

So what's confusing to me is that I wasn't ever sensitive to CRT flicker, and I'm not sensitive to plasma TV flicker. But something about certain implementations of PWM gives me crazy headaches almost immediately, even with no moving content.

I had a Dell Latitude for work that used PWM, but it didn't give me headaches (thinking back tho, it was so dim that maybe I just always used it at full brightness). However I also had a Lenovo Thinkpad that gave me crazy headaches. When I looked at the Dell through my phone, I could see kind of a "soft pulse" that appeared to travel horizontally, but when I looked at the Thinkpad I saw much more defined flicker artifacts like in this video: https://www.youtube.com/watch?v=4jrIUU6oFfM

The OLED iPhones have a similar headache inducing flicker "pattern" https://youtu.be/YuDA_WKDSdY?t=78
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Re: Sensitivity to PWM = sensitivity to DyAc?

Postby blurbustingbunny » 09 Apr 2019, 19:12

Chief Blur Buster wrote:Anecdotally over the years, with many coming to us about display ergonomic quirks, it's a more complicated question than expected. It depends on if your PWM sensitivity is from PWM artifacts or from PWM flicker itself.

Sensitivity to PWM flicker
That's the direct sensitivity to flicker itself.
Strobe-based blur reduction will probably bother you.

Sensitivity to PWM artifacts
Also often the same kind of sensitivity to stroboscopic artifacts from PWM lamp dimming (e.g. LED bulbs that flicker).
Strobe-based blur reduction avoid these artifacts for eye-tracking situations, as one-PWM-pulse-per-refresh.
So you might have less strain from this, and even tolerate it.
Image


Motion blur reduction can be a more eye-friendly PWM but it won't be friendly to everyone who has a PWM sensitivity.
Unfortunately there's no way to easily tell if motion blur reduction will help or hurt your eyes. but the good news is that display motion blur reduction is a feature that can be toggled ON/OFF.

Another way to reduce motion blur is simply sheer Hz (flickerfree). The use of flickerfree 240fps at 240Hz has one-quarter the display motion blur of flickerfree 60fps at 60Hz. (This is known as motion blur from the sample-and-hold effect).



If I am not sensitive to LED Clear Motion on a samsung TV, would I be sensitive to DyAc?
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Re: Sensitivity to PWM = sensitivity to DyAc?

Postby Chief Blur Buster » 10 Apr 2019, 13:08

blurbustingbunny wrote:If I am not sensitive to LED Clear Motion on a samsung TV, would I be sensitive to DyAc?

If your eyes tolerates LED Clear Motion on a Samsung TV, then probably not.

Samsung LED Clear Motion is a strobe-based motion blur reduction (blur reduction strobe backlights are "1-pulse precision PWM").

To avoid duplicate-image-related eyestrain, remember to have framerate = refreshrate = stroberate.

Image

So as a rule of thumb, increase GPU power, lower refresh rate, until your frame rates match your strobed refresh rate, and you've got motion nirvana.

However, one caveat:
The XL2546 is extremely bright, and you sit much closer than with a television.

As a result, follow these general practices for lowest eyestrain with motion blur reduction:
- Increase GPU power, lower detail, lower Hz, until fps=Hz
- Slightly increase viewing distance
- Add extra lighting behind your monitor (improve ambient lighting) so your screen is no longer the obviously brightest object in room
- Adjust brightness of strobe (or shorten strobe length / lower persistence in Strobe Utility) so it's not too bright.
- Possibly also turn off your strobe mode whenever you're not doing motion (e.g. static material like Microsoft Word)
- If you get eyestrain, try dimming brightness even further and use low-blue-light mode. (To cover the potential "red herring" or "wild goose chase" effect: if your eyestrain was unknowingly actually caused by excess blue light rather than from the flicker).

This will help ergonomics.
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Re: Sensitivity to PWM = sensitivity to DyAc?

Postby blurbustingbunny » 10 Apr 2019, 22:38

Okay interesting. I'll try playing on the Samsung TV first and see how it goes.

320cd/m^2 doesn't seem awfully bright, but IDK. My phones and tablets go to 500 easy
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Re: Sensitivity to PWM = sensitivity to DyAc?

Postby Chief Blur Buster » 16 Apr 2019, 14:44

Motion blur reduction modes use a strobe backlight technique (More info in Motion Blur Reduction FAQ.

Strobe backlight based motion blur reduction usually dramatically dim their displays, sometimes to below 100cd/m2, because of the bright:dark ratio.

Doing 1ms MPRT(100%) means the backlight is ON for 1ms and OFF for the rest of the refresh cycle. For 120Hz (8.33ms), that is quite a dramatic (1/8.33)th the original brightness -- 88% drop in brightness, unless using voltage-boosted strobe backlight flashes.

So a strobe backlight capable of keeping effective average brightness >300cd/m2 is plenty bright while simultaneously eliminating 80-90% of motion blur. The amount of motion blur reduction is directly proportional to the pulse relative to refresh cycle. So 1ms/8.3ms for a 1ms flash at 120Hz, reduces display motion blur by 88%.

Image

Strobe backlight modes typically achieve the bottom-most UFO in motion clarity seen at http://www.testufo.com in full motion at 960 pixels/second, for framerate-refreshrate matched motion.
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       To support Blur Busters:
       • Official List of Best Gaming Monitors
       • List of G-SYNC Monitors
       • List of FreeSync Monitors
       • List of Ultrawide Monitors
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Re: Sensitivity to PWM = sensitivity to DyAc?

Postby Vega » 26 Apr 2019, 01:17

From my experience, PWM gives me quite the eye-strain and strobing like ULMB and DyAc doesn't.

I chalk this up to strobing is usually timed perfectly to strobe once per frame right at the best/clearest moment of pixel/frame transition. In crappy PWM displays, the PWM controller is independent of the screen refresh. This means the "pulse/flicker" happens routinely at the worst times in the screen/pixel refresh cycle.
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