How to use Blur Trail / PWM test?

[CorvusCorax]

In my research, what cause headache and eyes strain in my new monitor I found info that PWM can be an issue.

If I see something like this it's OK or not?

[CorvusCorax]

Nobody? It's hard to answer simple yes or no? Sorry for my annoyance, but I'm desperate here trying figure out what's wrong with me or my new monitor.

[axaro1]

Alas, there's a lot of potential things at play here:

-- LED Blue light (but the old Samsung was also LED)
-- Ghosting (but some of the displays don't have much ghosting)
-- PWM dimming (but the XL2430 is PWM-free in non-strobed mode, though the C27FG70 reportedly had PWM)
-- Room lighting

Etc

From what was written, it is extremely hard to diagnose your type of eyestrain. But one thing you can test is high quality orange glasses -- SCT orange glasses -- can make a major difference for some people.

Also, in place of F.Lux, Windows 10 has a Night Mode that can help, though it can't reduce the blue light coming from LCD blacks (which sets the guaranteed minimum blue light that an LCD will always emit). Only physical filters will help with that, if you have an extreme blue-light sensitivity of some kind.

Note: When I say extreme blue-light sensitivity, I refer specifically to the blue sharp peak (~465nm) of common blue LEDs that are used to manufacture white LEDs (via phosphor coating on blue LEDs). The blue sharp-peak will still exist in LCD blacks even with the best orange-colored software you have, and it just seems that some people are just hyper-sensitive to this wavelength (far beyond a circadian disturbance).

Common rules of thumb:
-- Adjust viewing distance (including setting up display slightly further away)
-- Try to be PWM-free
-- Try to lower blue light amount
-- Try a higher refresh rate
-- Try making sure that lighting around the screen is proper (screen not the brightest nor darkest object in front of you)
-- Try adding/reducing motion blur by raising/lowering refresh rate (Reduced motion blur helps some, but increased motion blur helps other)
-- Adjust your viewing angle if you're using a viewing-angle-sensitive panel (VA, TN) that causing some eyestrain from viewing angle
-- Test VSYNC ON or GSYNC or FreeSync (for some users, VSYNC OFF microstutter/tearing gives eyestrain)
-- Test blur reduction + VSYNC ON (if you have an extreme motion blur sensitivity)
-- Obtain a color calibration device (such as a Spyder) and try recalibrating to a good gamma curve. Try out high gamma and low gammas and see how they respond with your eyes.

It may even be a compound mix of multiple of the above causes.

If you are spending lots of time doing lots of motion, and a clearer monitor is forcing your eyes to exercise a lot more than usual -- then you may have a different kind of an issue. Were you getting eyestrain with Overwatch with your original TN panel?

It can be quite difficult to drill down to the precise issue you're having. That can get expensive mind you, to try to drill it down to the causes you're having, especially if your doctors are unable to diagnose you (usually they can, but the 0.1% cases are particularly pesky).

Some comments:

-- Have you tried adjusting your environment? Making sure your room is brighter versus darker? Light added behind a screen?
-- What kind of lightbulbs do you use in your room? Do you get strain from various kinds of lightbulbs?
-- No, IPS glow doesn't tend to affect amount of blue light. But the overall brightness of the black may. But it's often less than one-hundredth the amount of blue light of a bright screen.
-- Higher Hz doesn't affect blue light. But can help you a huge deal if you have eye pain from motion blur.
-- Have you tried televisions too see if viewing distances play a role in your eye pain?
-- Yes, dimmer means less blue light. Halving backlight brightness on a monitor will halve blue light.
-- F.Lux doesn't fix the blue light still being emitted by the grey colored blacks, so dimming the backlight AND using a low color temperature, is usually the best way.
-- "Eye Care Technology" can help but it doesn't always help blue light emission from dark colors/grays (unless they are using high priced backlight LEDs similar to high-CRI LED lightbulbs).

Everybody's screen prescription is different, and Blur Busters are not doctors, but we've from time to time successfully troubleshooted our way (stutter/blur pain example) but your situation appears different) to a more vision-friendly monitor for an unusual eyestrain case.

PWM-pain, stutter-pain, motionblur-pain, brightness-pain, we've seen it all here (by email, forum, social, etc). Everybody's vision is different. We're a wealth of data on screen-discomfort by sheer accident of being Blur Busters. While it's not our primary topic matter, we'll probably write an article on this topic matter. But your case is a little more complex than average.

Yesterday, CRTs were smaller. Today, screens are bigger and emit more blue light. So we've got a simultaneous onslaught of size/light/blur/brightness/etc changes. So it's not always easy to hone-down the specific category of change. Sometimes it was just the size, sometimes it was just the motion blurring (we're Blur Busters, after all...), sometimes it was just the blue light, sometimes it's all the above.

That said, you've come to the right place because there is nowhere else on the planet that has seen a reliably huge gamut of display strains (pain from stutter, pain from motion blur, pain from blue light, etc) simultaneously. All those ergonomic recommendations elsewhere are so narrowscope (PWM focussed, blue light focussed, etc). But we're quite broadband as The Perfect Motion Company, in the refresh rate race to retina refresh rates, where displays someday look identical to real life, with identical effects. Displays are still far away from that, creating pains on displays that don't create pain in real life. So without further ado, here's an attempt #1 for you:

Try the following simultaneously

(A) Stick to PWM-free; and
(B) Use your orange glasses; and
(C) Increase viewing distance slightly (use big DPI to see text better) so screen is smaller in your vision field; and
(D) Much lower brightness via monitor controls; and
If monitors won't go dim enough, purchase a neutral density plastic film to put in front of monitor to make it even dimmer. Sometimes those bright monitors become good once you extend their brightness range that way.
(E) Adjust your room lighting so that your screen is never never never obviously the brightest object nor the dimmest object in the room. Spend the money on proper good lamps with high-CRI light sources (e.g. incandescent lights or CRI 93+ LED which costs more) on a dimmer to rebalance your room lighting; it makes a BIG effect in making screens more friendly. Move those 50 cent LED lightbults to your closets, purchase those "high CRI" dimmable LED bulbs, look for something with a "93" or higher in CRI. And make sure to use high quality LED-optimized dimmers like Lutron rather than the cheap triac-based PWM wall dimmers. Don't settle for anything below CRI 90 with your LED lightbulbs, in your computer room, ever. If you wish, you can even attach the same automation method to all of them if you want to dim them all simultaneously quickly via one touch of a remote/smartphone, so you can more easily rebalance room lighting to match your screen better at night vs day. IMPORTANT IMPORTANT IMPORTANT: Anything you do to completely prevent your screen from ever being the obviously-brightest object in room, or obviously-dimmest object in room, helps a lot. So do not spend money only just only on the screen; you need to fix your room lighting too in a particularly severe eyestrain problem situation like yours. Screen too dim but brighter screen hurts more? Dim your room. Screen too bright but dimmer screen hurts more? Brighten your room. Screen fine at day but hurts at night? Use dimmer to adjust room lighting to fix. You get the idea. So it's important to install flexibility to adjust your room lighting. Etc.

Fine Tune Tweaks
(G) I don't have enough information if motion blur and stutter are components of your eye pain, but if it is, then also use a high refresh rate (120Hz+) combined with a powerful GPU, combined with VSYNC ON or variable refresh rate (GSYNC/FreeSync). If not using GSYNC/FreeSync, try to keep frame rate matched to refresh rate to prevent strain from stutters;
(H) If you test motion blur reduction again with games, make sure you you also fix your mouse microstutters too. That said, you appear to have a PWM-pain, and motion blur reduction may not be enough to compensate.

I am no doctor, but so many people overlook some common sense vision ergonomics for eye-pain-sensitive people.

Did you experience the same issues with other 240hz monitors? What monitors have you used so far?

[CorvusCorax]

Thank you for answer, I appreciate.

Yesterday, after few hours of sitting in front of the monitor (Dell AW2521HF, it's IPS, 240Hz) I had a nausea and dizziness. It's was serious, I almost throw up. Yea, I know it's stupid strange. For now I can't use this monitor. I went back to my old one Dell 2209WA (IPS, 60Hz).

For now I checked:
1. Preset Comfort View in OSD + Night Mode in Windows.
2. Lowering Brightness and Contrast.
3. Changing lights in room and setup up monitor for more distance.
4. Changing all refresh rate (60/120/240). For sure it's on some way related to refresh rate, because 240Hz is the worst option.

It's my first 240Hz monitor but I had few monitors before for testing (Asus, Acer) and problem was not occured, but I had them only for few days.

In my job I spend 6-7hours in front of Dell P2414H (it's IPS, FHD, 24", 60Hz) with 45/45 brightness/contrast settings. No problems at all. Same with my old monitor Dell 2209WA (IPS, 60Hz, 22").

I have to figure that out for future buying options. I will finally sell AW2521HF or throw it trough window.

[Chief Blur Buster]

In my research, what cause headache and eyes strain in my new monitor I found info that PWM can be an issue. If I see something like this it's OK or not?

That photo doesn't reveal PWM.
To use that test correctly, track your eyes on the moving line. Do you see just a solid motion blur or a broken motion blur? A broken motion blur indicates PWM.

Also, AFAIK, that monitor is PWM-free.

_________________

Does problems disappear if you stay at 60Hz at desktop?

Any prior high-refresh-rate experience of any kind? 120Hz? 144Hz? 240Hz?

-- Motion Sickness: A small subsegment of population has a motion sickness caused by high refresh rates being too smooth -- it is why Apple has a "Reduce Motion" setting for iPhones. For those people, it is usually only solved by staying low frame rates (10 to 30fps). Some of it is solvable by staying at a low refresh rate at Desktop (so scrolling/etc doesn't produce motion sickness), and only using a high refresh rate for games.

-- Coil Whine: Another issue is coil whine. Near-unhearable sounds can cause nausea. Many monitors makes near-ultrasonic sounds that changes with refresh rates. Some high-frequency switching power supplies hidden inside monitor sometimes have a near-ultrasonic sound to it. Sometimes you can't hear it but its sounds sometimes cause people to throw up (like a faint near-ultrasonic). The coil whine is worse at 240Hz on some monitors. This is hard to trace if you can't really hear it. I know that continuous exposure to sounds can cause people to feel sick. If you have a glass wall or glass window inside your place, try putting monitor on opposite side of the glass wall and see what happens. Keep the monitor's power brick there too, though coil whine can come from monitor's back or even from monitor screen glass too (vibrating in sympathy to the electronics on the rear). If your nausea disappears when your monitor is noiseboxed this way, then you found your problem.

-- Motion Blur Nausea: Another potential is nausea by motion blur that only occurs beyond stutter vibration threshold (>60fps) and below zero-blur threshold (ULMB). Your last option is to test motion blur reduction. Try ULMB at 144Hz and temporarily play games VSYNC ON (or RTSS Scanline Syunc) at perfect framerate=Hz and see if it helps any. Lower your refresh rate until you get perfect framerate=Hz. It will flicker/strobe a lot more but you have zero motion blur.

[CorvusCorax]

In my research, what cause headache and eyes strain in my new monitor I found info that PWM can be an issue. If I see something like this it's OK or not?

That photo doesn't reveal PWM.
To use that test correctly, track your eyes on the moving line. Do you see just a solid motion blur or a broken motion blur? A broken motion blur indicates PWM.

Also, AFAIK, that monitor is PWM-free.

If I track my eyes on the moving line it's solid, so looks like I can cross out PWM from my list. Thanks.

Does problems disappear if you stay at 60Hz at desktop?

Yes and no. It's little more comfortable for me, but in 60Hz is see flickering and it's so obvious that any person can see it.

Any prior high-refresh-rate experience of any kind? 120Hz? 144Hz? 240Hz?

As I wrote above there was time when I tested some monitors from Asus and Acer (144Hz), but I had them only a few days. No issues.

---

I dont think motion sickness is the problem for me because I can look at static picture and still feel discomfort.

Maybe it's coil whine... because when I switch from 120Hz to 240Hz I hear high sound from back of the monitor. But in other hand my problem still occurs in lower RR.

Motion Blur Nausea is not the problem, as I stated above I feel sick even when I watch static desktop picture.

---

I know that my problem may be very abstract for some peoples, but for me is very important because using PC is my job and my hobby. I have to figure that.

One last thought. When I look at the screen I instantly start to feel sick. It's like trigger. When I turn off monitor I'm starting to feel better. So, using this monitor switch something in my brain like on/off.

[Chief Blur Buster]

Near-Ultrasonic Audio Emitted From Certain Models Of Monitors Can Cause Headaches

Maybe it's coil whine... because when I switch from 120Hz to 240Hz I hear high sound from back of the monitor. But in other hand my problem still occurs in lower RR.

Bingo. Here's a possible cause.

It may not solve your problem, but please test it and report back if it solves your problem.

Coil Whine Does Not Need To Be Fully Audible To Create Headaches

Even when coil whine become so quiet (threshold of hearing), it can produce nausea. You did say you get less nausea at lower refresh rates, but that it's still there. It can modulate louder and quieter, especially during refresh rate changes, but it's still there, tickling your minimum whisper hearing threshold so you can't hear the sound, but it's a nauseating audio frequency for some.

Test #1: Spin Your Computer Chair 180 Degrees

Sit in completely opposite direction staring at real world 180 degrees away from the monitor, with the monitor only 1 feet behind your head.

Sometimes nausea only occurs with your eyes open staring at the real world (even if not staring at the monitor), so closing eyes while facing screen does not always work and may create wild goose chases of other monitor-nausea causes (bright flicker or blue light leaking through closed eyelids)

If you are still getting nausea even while staring away from monitor (with monitor 1 feet behind your head) -- then there is a VERY high probability of nausea from the near-ultrasonic noises of some monitor (coil whine). Some monitors makes a lot more than others.

Test #2: Glass-Insulate Your Monitor

Once you confirmed Test #1, you can progress to an additional verification test (seeing monitor) may be needed, which requires a bit more creative testing because not everyone has a glass box to test with:

• Plywood Box with Plexiglass Front
  If you are a good DIY builder in a woodwork lab, this is obvious. Be creative! Don't forget to add cooling mechanisms since a closed box can overheat a monitor (cooling ideas such as a fan hole on the side, but you also have to find a way to sound-insulate the cooling fan holes!)
• Aquarium Tank As Monitor Noise Shield
  Test your monitor in a glass box. A large aquarium tank put over the monitor, is one method of blocking most of coil whine. Purchase a sufficiently big aquarium from Amazon and briefly test with it upsidedown on the monitor (easiest) or create a custom lid if keeping tank right-side-up (harder). Thicker the glass, the better. Make sure to put the monitor on a rubber mat or mousemat-style thing, to prevent coil-whine transmission to the desk surfaces). Seal up gaps caused by power/DisplayPort cables. Once you've determined an aquarium tank solves your headache problem, you can turn the aquarium tank permanent. The aquarium box can be a permanent coil whine noise shield, as long as you find a way to ventilate the box; 50-100 watts of heat builds up really rapidly inside a glass box.
• Opposite Side of a Window
  - Try putting your monitor at a house window, and going outdoors to try to view your computer monitor through your window.
  - If you have it in an office with glass walls somewhere, try that too (bring your monitor to work; some conference rooms have glass walls.
  - If you have a car, try putting your monitor on an outdoor driveway table/cart and facing it to a side car window. Sit inside your car while staring at monitor with all windows closed and outdoor vents sealed off (internal-circulate, like you usually use when highway-passing a soot-spewing diesel semi trailer), to make your car a noiseproof box.
  - If you have a French glass door, try putting on opposite side of door and seal the door cracks

Be creative to find a way to glass-insulate the coil wine in a test, and you'll instantly notice you no longer get headaches when staring at the screen.

WARNING/IMPORTANT/DISCLAIMER!
1. Be VERY CAREFUL of glass aquarium tanks, they can easily shatter, and sharp glass can be killer knives. But you knew that.
2. Be VERY CAREFUL when transporting the monitor, we disclaim responsibility for a broken monitor while carrying it around.

Some bad coil whine may break through, but it will be much less. Coil whine is a major nausea problem for some people. I've chased this ghost already; It's a frequent red herring & wild goose chase misappropriating TN defects and refresh rates, for mudane issues such as near-ultrasonic sounds emitted from monitors.

Use external speakers, since you no longer can use monitor internal speakers anymore, when you're sound-insulating your monitor from problematic coil whine.

Not All Monitors Have Bad Coil Whine

You may also try monitor lottery (RMA or switch brands) until you find one with little to no coil whine. But if you're in love with a specific screen, noise-insulating your monitor is a perfectly legitimate option.

Also, not everybody gets nausea from near-ultrasonic sounds such as coil whine. However, it is part of the troubleshooting box to avoid wild choose chases to visual red herrings (visual nauseas related to flicker / blur / stroboscopics / blue light / etc) since audio headaches is part of monitor ergonomics.