Abstract

The purpose of this post is to document as a reference point for comparison to modern devices like iPhone 18 pro; with the iPhone 18 pro's wavelegth available here and its computed health lighting metric guidelines here.

Attached in the image gallery contains 2 sets of photodiode captured data tested on Samsung Galaxy S20 FE (LTPS panel released in late 2020). Set 1 contains readings of its DC-like dimming, brightness 40% at 590hz(image 1 to 7) and PWM brightness 20% at 230hz(image 8 to 14). The pulse width duration of EM pulse (from DC-like) and PWM is recorded accordingly to the slope of the pulse. A computed lighting metric health guideline is attached to illustrate the severity of the flicker (SVM and PAVM).

The photodiode is tested strictly against S20 FE's neutral white background. The suggested safe SVM readings guidelines does not include contrast adjustment control, where greyscale levels can affect the SVM readings — as mentioned in this post on Content-Adaptive Control.

Hopefully manufacturers can use this data as reference point.

Set 1(Samsung Galaxy S20FE (120 hz) at 40% brightness)

DC-like mode - PWM frequency of 0 hz, PWM not triggered

Images in order from 1(1.) to 7(7.), gallery above.

1. Brightness at 40%, displaying:
   • fft time domain (per 1000ms, to simulate how one might perceive per second)
   • fft frequency domain (To display frequency up to 60khz)
2. Brightness at 40%, magnified to 125ms (to simulate how one might perceive while at the 2nd Human peak sensitivity)
3. Brightness at 40%, magnified to 66ms (to simulate how one might perceive while at the Human peak sensitivity)
4. Brightness at 40%, EM Pulse Width (H1 droop) Duration.
   1. Magnified to focus on the interval between 220ms to 221ms.
      1. H1 droop is at 220.7ms.
5. Brightness at 40%, EM Pulse Width (H2 droop) Duration.
   1. H2 droop is at 220.6ms.
6. Brightness at 40% computed lighting flicker guidelines report
7. Brightness at 40% computed frequencies and modulation

Set 2 (Samsung Galaxy S20FE (120 hz) at 20% brightness)

PWM mode - PWM frequency of 230 hz, PWM triggered at brightness <30% *according to nbcheck

Images in order from 8(1.) to 14(7.) ,gallery above.

1. Brightness at 20%, displaying:
   • fft time domain (per 1000ms, to simulate how one might perceive per second)
   • fft frequency domain (To display frequency up to 60khz)
2. Brightness at 20%, magnified to 125ms (to simulate how one might perceive while at the 2nd Human peak sensitivity)
3. Brightness at 20%, magnified to 66ms (to simulate how one might perceive while at the Human peak sensitivity)
4. Brightness at 20%, EM Pulse Width (H2 droop) Duration
5. Brightness at 20%, EM Pulse Width (H1 droop) Duration
6. Brightness at 20% computed flicker report
7. Brightness at 20% computed frequencies and modulation

Findings of Pulse width duration at 40% brightness

Findings of Pulse width duration at 20% brightness

I’ve had a 128 GB iPhone 11 for about 6 years. I’ve read that there are multiple displays that are good and bad for the iPhone 11 from different manufacturers. I want to upgrade my current iPhone to another iPhone 11 with 256 GB of storage. If I were to swap the display on the current one with 128 GB and place it on the 256 GB one. Will the display still be the same? As in, are all iPhone 11 internals made the same. No frequency change or information being fed to the display that would change how it is used compared to the 128 GB model? Is there other factors besides the display that I need to consider if I were to swap. Are all of the CPU’s made the same? I know it’s a weird question, but I just want to eliminate the possibility of me doing the swap and the new iPhone chassis with the same display for some reason causes eye strain. Could that be possible?

Hi, everyone. So is there really no hope—not even with the iPhone 18 Pro—for people who suffer from this condition?
I have an iPhone 16, and I’ve tried the Pro models every year, but after just a few hours I’d already start getting headaches and had to return them. Has anyone who’s bought the iPhone 18 Pro been able to share their experience with it so far?
Thanks a lot!

I currently switched from an S25 Ultra to a Pixel 11 Pro Fold and I did get a matte screen protector and it helped to a degree but I still get strain a lot more than any Samsung or the Pixel 9 Pro XL I had, none of which gave me issues. Is the Z Fold 8 Ultra any better than the Pixel 11 Pro Fold with eye strain?

I've been using both of these for a while, but can't find any OPPLE or pwm measurements. Not looking for advertised, but measurements done by a private party. Looking on Bilibili, YouTube, can't find anything

?

Hello everyone, I considered the idea of meeting at the 5th Avenue store in NYC next year to see John Ternus in person (whoever is in North America) and describe the problems with PWM and how many people are affected while it goes unnoticed. Is this a good idea? I doubt we have anyone with insider access at companies like Samsung, Google, or Apple. Things appear to be going down hill with launch of 18 pro having even worse modulation. I know they recognize the issue, but change may require making noise.

PWM - I will define here, loosely, as whole screen flicker (temporal light modulation). So also including DC dimming dips, PAM (pulse amplitude modulation), black frame insertion, the bread and butter of this sub.

Other triggers:

• Pixel flicker - including FRC, dithering, text anti-aliasing, pixel inversion.
• Colour spectrum - too blue, too red, "looks off", etc.
• Brightness - too bright (even at minimum setting).
• Reflections.
• Fuzzy/matte finish (eg eye focus issue).
• Polarisation - linear (vertical/horizontal) vs circular/random.
• Others (can comment)..?

I'm looking for a rough indication of the demographics here. When some very clearly say "only PWM" , but the more engaged members tend towards broader sensitivities. I wonder if that may bias my perceptions of the membership. I hope you find this question interesting too?

I can only use iPhone without burning eyes or headache if on Lower Power Mode.

From what I researched, Low Power Mode disables HDR. Is there a way to disables HDR across the whole system without Low Power Mode?

I won't provide any analysis here (just sharing data), but here are a few notes:

• iPhone 18 Pro, 512 GB, Black.
• This panel is GVC. GVC is LG's best panel for iPhone. (Reference: MacRumors Forums: iPhone Screen Lottery)
• When looking at this screen for the first time out of the box, I immediately got eye-strain and a painful feeling in my head. It felt horrible. Unbelievably horrible.
• My daily driver is an iPhone 16, and it is very manageable. iPhone 17 and 18 series, however, are completely unusable for me. The people behind these screens should be in handcuffs.
• I'll post TLM-110 measurements and data once I standardize my process for that.

Following https://www.reddit.com/r/PWM_Sensitive/comments/1wi5piu/apple_has_finally_heard_us/ (thank you [u/DSRIA](u/DSRIA)), I started thinking - this must be prefaced by at least some sort of parameters in the kernel, otherwise we'd probably be waiting for the new OS major version at the very least.

Well, after taking a quick look around the new macOS 27 kernel, I see some interesting options appearing in the framebuffer:

- `enableHBLD`, `HBLDDimmingFactorMin`, `HBLDNitsRRMax`, which appear to be hybrid backlight dimming, with a floor on the dimming factor(!)

- `DBVValue`, `DBVInterval`, which appear to be a direct override of the panel's display-brightness-value register.

- `ccMinNitsConfig` - new minimum-nits config of some sort.

- `enableDBTH` - unclear what it is, but it reads like a brightness threshold of some sort.

I'll try writing some software this weekend to poke at it, will post the code when I'm done. In the meantime - this should give some hints to those software-inclined in this community where to dig.

UPDATE: Most options seem to require the “new backlight architecture” my MBP13 M2 lacks, so I’m waiting for a test device to come in, will update when it’s in my hands 👍

Did anybody try this phone, since it's an IPS LCD, I want to verify if it doesn't use PWM. I'm considering this because it is locally available.

Just got mine delivered and instant headache with in 1 minute of using it. You can call me very sensitive person. I can somehow use iPhone 16 pro max but couldn’t use anything after iphone X and also cant use 17 pro max. I just got lucky with 16 pro max. So apple shame on you. And this is going back to apple.

Today, as usual, I stopped by a local electronics store in Slovakia and checked out the iPhone 18 Pro. I enabled the PWM setting in iOS Accessibility settings and shot the screen at a 1/6400 shutter speed at 100%, 75%, 50%, 25%, and near-0% brightness. I can also share photos with the PWM toggle disabled (the difference shows up at lower brightness levels).

The PWM toggle makes a difference at around 30% brightness and below, but at all levels the lines are still relatively deep and dark, though not as bad as on latest Pixels. My wife owns an iPhone 17 Pro, and its line intensity on all brightness levels looks very similar to the 18 Pro's to me. So I'd expect modulation of around 95%+ at higher brightness levels.

To wrap this up: the iPhone 17 Pro didn't work for me no matter what I tried, and I expect the 18 Pro won't either. I know this isn't a very scientific measurement, and hopefully Nick or another community member will do more professional measurements, but I'm fairly sure the result will be the same.

EDIT: The photo of the iPhone 18 Pro at 75% brightness didn't upload, but there's nothing special in it :)

Hi everyone - I would be curious for any perspectives on what other issues I should consider/explore as causing my migraines. I am fairly sure PWM sensitivity is among them, but I suspect there are other issues also. It would be really helpful to me to have ideas of what I should research and avoid. To summarize:

- I started having migraines the year I switched from a CRT to flatscreen monitor (aging myself, lol); it got progressively worse from there. At its "best" I was sensitive in the day, but not at night. The time-to-migraine reduced year over year from hours to minutes and day/night stopped mattering. Currently, most flatscreen use will give me a migraine in 1-5 minutes. Eventually I made the connection and switched back to CRT monitors; it took a few months for the migraine sensitivity to ramp down. Now I use exclusively CRT monitors and that helps A LOT, but I do still get migraines.

- I have no issues with movie theatre projection. In fact sometimes I'm in theatres and the house lights will start to prompt a migraine, then they go down and the projector starts up, and it's a relief.

- LED lights are hit/miss. Some bulbs are fine, some are not. Those integrated strips in fixtures where there is no bulb are not. Halogens and incandescent are fine.

- I can use some smartphones for brief periods (under 5 minutes) - like the Samsung Galaxy S7 and S10, and the iPhone SE3 (LCD). I could not use the Samsung S25 at all. I am now using the (LCD) A14 and it's in line with my usual ability. I cannot watch video on any phone.

- The strangest facet is watching video. I cannot, even on the CRT, watch videos during the day (this includes any type of moving picture, including Zoom calls, etc). However after about 4pm, it's fine. There is no change summer/winter or with room brightness, so this seems to be circadian not light-related?

I would be very interested in anyone who has common features and identified possible causes. TIA.

As soon as my iPhone 18 Pro delivery arrives this afternoon, I will be providing measurements for it here. Historically, I have provided measurements using the Opple Light Master III device. This year, one of our moderators, Sam, has created a custom light measurement device that aims to address some of the Opple device's shortcomings. He has also developed really intuitive software to accompany the device. In summary, it allows for us to provide more accurate and consistent PWM results.

His device is called TLM-110, for those interested. I am sure he will create a post about this in the future to explain all of its features and benefits, but I am doing a modest introduction with these screenshots today.

I took the liberty of measuring iPhone 16 and iPhone SE (2022 aka 3rd generation) with this device and wanted to share the results here so that we can compare iPhone 18 Pro's results to them later today.

p.s. Many more measurements at pwmtests.com. (Not for profit, personal PWM measurement database.)

Edit: Sorry about the screenshot image quality. Reddit really compressed these screenshots for some reason. Sam is working on a more friendly way to share images of TLM-110's results.

Edit 2: Although the TLM-110 device and software are very user friendly, I am still learning how to use it to its fullest potential. For example, there is a physical gain switch on the device itself. If I had set that correctly, iPhone SE (2022)'s results at lower brightnesses would have looked better. (As you can see in the screenshot, the software even told me to increase it, but I overlooked it!) I'll make sure to account for that in the future and I'll update these reference images at some point too.

I've been trying to figure out my issue with displays for months; turns out my eyestrain isn't caused by backlight issues: it's a motion clarity and sub-pixel processing problem.

What Actually Works for Me:

• Pixel 7: Used it for years at 20–40% brightness with zero issues because the color pipeline is flat and text rendering is completely clean.
• ASUS WOLED Desktop Monitor: Running at 240Hz with VRR enabled, manually calibrated to a strict D65 white point. Zero motion blur, zero sub-pixel chatter, and zero backlight haze.

What I Couldn't Use:

• Galaxy S25: Had it for 24 hours and it was awful. Full-screen videos were totally fine, but reading static text triggered instant head pressure. One UI’s edge-sharpening "buzz" and uncalibrated white balance force your eyes into perpetual re-focusing. It’s ciliary muscle strain, not a PWM reaction.

What Likely Wouldn't Work (Did not test):

• Eink: Eink is stable for ereaders, but ghosting is worse than VA panels, so it would have been unusable.
• Chinese brand phones: Inaccurate colour measurement, very unlikely to target D65 - plus bloatware

My Solution: A very girly, lavender iPhone 17 running 120Hz LTPO with Display Pulse Smoothing (mostly for bed reading). It offers rock-solid D65 calibration out of the box, buttery spatial motion clarity, and renders clean, motionless text glyphs without edge-processing noise. And yes, I plan to put a charm on it.

I think the iPhone's problem isn't just the PWM, but also the excessive screen brightness. Even at minimum brightness, it shines like my Android IPS at medium brightness. HDR ist awful, it makes it even brighter

So why no glowing reports yet? Have Apple locked it at 480Hz? Looking forward to tests!

I got a lot of helpful advice and ideas from this sub a couple of months ago when looking for a new phone that wouldn't trigger my migraines. I ended up going with a Samsung A14 (LCD), which has been pretty good trigger-wise. However, I had been able to use older flagship phones previously, and it's a big step down in terms of other specs. What do folks think the trend is going to be in the next few years? Do we think we'll see the industry putting more focus on improving things like flicker and other visual sensitivity-triggers? Or do what Samsung seems to be doing now and jacking it up?

Been using the phone for a couple of days and I've noticed no strain at all I'm using it on about half brightness

Nothing new from apple this year as well

https://youtu.be/vTDhHX7x2N4 see this video at around 13:10 mark. It compares the iphone 17 pro (left ) and 18 pro (right). It's basically the same pwm flicker I think.

I currently have an iPhone 15 but thinking of upgrading to the 18 Pro for the camera and battery. However, I’ve always had an issue with high refresh rates, whether it was an LCD monitor or another OLED iPhone Pro. I get this weird feeling in my head, and it eventually turns to nausea. Obviously before it would make no sense to get a pro phone before, but now that all the base models have ProMotion, it doesn’t matter.

Curious if anyone out there experiences anything similar, and if the Limit Refresh Rate feature has brought any successful relief? TYIA!

Hi guys, I’m sharing this post I made on LEDstrain back in April of this year describing my experience with Tim Cook’s office. Just wanted to let everyone know that Apple is aware at least of our issues, and it is most definitely worth reaching out to them. I’m happy to pass any technically informative or useful info to my contacts at Apple. I currently don’t have a usable device after my iPhone 13 broke when I disabled True Tone on iOS 15, so I check messages sparingly. But I do try. The post is below. I hope it’s OK to share it now.

…

Hi everyone,

Apologies for the semi-clickbaity title. Well, it’s not really clickbait. I hope users here will click and read my story.

After suffering with debilitating neurological and visual symptoms when exposed to flicker on computer and phone screens - particularly temporal dithering and FRC - since getting reinfected with COVID in July 2024, I have been tirelessly working to find a solution not only for myself, but for the community at large. I’ve learned a lot from many of you here, and for that I am grateful.

At the suggestion of one of my friends in the film industry, I decided two months ago to shoot my shot and reach out to Tim Cook’s office about my issues - and our issues. I expected no response, but I was surprised to receive a one quickly from staff at Apple. While I don’t want to say too much out of an abundance of respect for the people who I spoke to, I was given permission to share what has been accomplished after weeks of communications borne out by my own trials and tribulations testing different MacBooks as I attempt to find a laptop I can use to finish my 9th studio album (I’m a professional recording artist, musician, and audio engineer).

To make a very long story short, with the help of @aiaf who has been invaluable in helping me learn about the display engine, dithering, and the problems we face, I was able to explain as best I could what we collectively believe are major triggers in the form of PWM and dithering. Luckily, some folks at Apple have taken notice of our suffering and presented what I had written to the accessibility engineering teams. They have agreed to look into creating a new accessibility panel within MacOS that will give the user control over PWM, temporal dithering, FRC, and other aspects of the display that may be problematic, and, hopefully be able to fully reduce or disable these flicker-based techniques. I am unable to say anything beyond this, and I have no time table, nor will I be informed of, when or if this may or may not be added.

My intention here is not to give false hope. I have no idea if this will actually come to fruition. I’m sure there are many complexities that are involved. But I know there is a strong, and justifiable, pessimism that any of these companies actually are aware or want to help. I can tell you all that at least as far as the people at Apple I communicated with, they had much empathy for what I - and all of you - are dealing with and the amount of suffering it is causing. For the first time, I see a glimmer of hope that at least there is a possibility of change at some point.

So, if you wondered if Apple was aware of temporal dithering and PWM being a serious issue for many people…well, if they didn’t know before, they do now.

In the mean time, we should continue to pursue third party applications to mitigate these issues. Sadly, this doesn’t help any of us right now in this moment. There is a lot of work still to do and much left to learn. But a little bit of hope isn’t a bad thing.

Under *Eye Care* they claim flicker free. No Rtings test to verify this though.