Apple Has Finally Heard Us

AshX

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.

Ash

Z3R0Gravitas

AshX - Great work dude! Here's hoping all suffering and efforts with Apple pay off and percolate through to copy-cat manufacturers, too. (If they don't take the lead in the mean time.)

anon123

AshX That's huge. Please, if they contact you again, could you also mention integer scaling? macOS doesn't offer true 1:1 or 2:1 pixel-perfect scaling (even in 2x mode).
A simple toggle to force integer only scaling ratios would be hugely helpful.
Apps like BetterDisplay can force integer scaling (true 1:1 pixel mapping), but only in streaming mode which introduces a lot of lag.
This mode removes a lot of antialiasing and visual noise. Credit to @DisplaysShouldNotBeTVs for discovering that.
I recommend trying this if you guys have trouble focusing on HiDPI displays making the display "calm" and not vibrant shaky looking.
Thank you.

Newscreensarehorrible

AshX I can't wait!!!!

photon78s

Just saw this article from the Los Angeles Times:

https://www.latimes.com/lifestyle/story/2026-04-06/new-vogue-spa-eyeball-care-review-digital-eye-strain

More than half of the U.S. suffers from digital eyestrain.
This little-known “Eyeball Care” massage aims to increase circulation and relax muscles in the eye area.
The treatment includes a diving mask filled with cool, aromatic mist and an eye socket massage.

When she was growing up in Guangdong in Southern China, elementary school students were given a break every afternoon to perform “eye exercises,” which involved gently massaging pressure points around their eye areas, for 5-10 minutes.

“It released eye stress because we studied from eight o’clock in the morning until almost noon time,” she said. “It was a break for our eyes to prevent nearsightedness and tired eyes.”

photon78s

Simple eye exercises

AshX

Z3R0Gravitas

Thank you. Me too!

Clokwork

It’s possible iOS may be included (I requested both) but perhaps because my focus was on professional use (music production) MacOS may have been prioritized. I won’t speculate beyond saying I did bring them both up as I cannot use any of the newer versions of iOS.

AVE10N

Someone has reached out to NVIDIA - or so I’ve read on this forum. For what it’s worth, I’m quite ill (long COVID along with 26 other diagnoses, including autoimmune issues) so it wasn’t easy for me to do this. But I recognized no one else was going to and I’m not the type of person who waits for others to solve his problems if I have any say in it. That being said, there are limits to what we can accomplish alone.

. . .

I also forgot to mention in my post to please reach out to Apple, especially accessibility, if you feel like it and share your own story and experiences - especially if it relates to a recent Mac or iPhone purchase and return. I was quite concerned after I suffered a seizure using the MacBook Neo I purchased, particularly because this laptop will be used in schools. So I felt some urgency to bring that to their attention.

I did quite clearly mention there was a large community affected by this across different forums, but I think hearing from others who are affected would go a long way toward encouraging Apple to devote the resources necessary to make this happen sooner rather than later.

While I am optimistic that this may be addressed some day, we have to keep in mind like with all large corporations, there are many different chefs in the kitchen with their own projects and goals. I think by respectfully sharing your own story and struggles with temporal dithering and PWM, it will only help to humanize this issue, and hopefully lead them to prioritize it even more quickly.

Clokwork

Excellent news!! Even if it is only MacOS, I will consider that a genuine win if this comes to fruition. I could finally be able to upgrade and be welcomed to the current era. Thanks for giving us hope.

AVE10N

I wish someone would contact Nvidia and finally ask them to add the ability to completely disable dithering. Not everyone has the energy and strength to fight corporations when it feels like the whole world is against them.

fpetterr

Thank you @AshX ! I hope we can finally upgrade our laptops once the accessibility features are added! 🤞 I also tried to use several Mac in the past couple of years, and while some of them were better, at the end I had to sell/return them because of dizziness, headaches, burning eyes.

(Edit: I stopped counting my failed attempts of using OLED iPhones & iPads 😅)

sakraycore

Thank you Ashx!

Hopefully Apple removes dithering from Macbook Neo. I had been wanting to give it a shot, but the dithering would be enough to stop me.

Donux

I am worried now, that if Apple would really fix pretty much 80 percent of all eye strain couses, there will be an existencial threat to this online forum community 🙂 No eye strain, No shared problem, No shared experience 🙂 Might as well rename it into ledcomfort.org. But as there is a saying - do not celebrate before you land safely after jumping over the cliff, lets postpone celebration when the problem will be fixed.

JTL

Donux Early on in this forums existence (circa 10 years ago) there was certain (perhaps naive) hope that if (actual) flicker-free monitors and GPUs without dithering or other output issues (was still somewhat a concern, even back then) resolved this issue the purpose of this forum would be moot and we could all go back to doing something else. Of course that didn't happen.

And while I'm not going to exactly celebrate unless something actually changes in our favor there are still other challenges to face then just the usability of Apple products.

brjdenis

Apple will remove dithering because customers wanted it, but the problem will persist. What will happen then?

AshX

brjdenis

My perspective has been that while there are other sources that can trigger visual and neurological symptoms, we cannot even begin to evaluate what else might be triggering these symptoms without first eliminating flicker.

As I indicated to Apple, the inability to get a “clean” flicker-free signal from the display engine makes it near-impossible to actually determine what might work for myself and others. Flicker either from PWM, dithering, transistor leakage, voltage issues, and so on is so destabilizing to the visual system that it must first be dealt with. It’s also something measurable that engineers can study and control as opposed to vague symptoms with no discernible cause.

There is longstanding, established mainstream epilepsy research indicating the severe effects of flicker 30Hz and below. 15-30Hz - the frequencies in which we have detected both GPU dithering and FRC - is the biggest risk factor for seizures according to decades-long medical research on epilepsy. The science is sound and established so I believe this played a large role in convincing Apple to consider this, especially given they added an accessibility setting to dim the screen when flashing lights appear to help prevent seizures in susceptible individuals.

My greater point was that there is an irony that this accessibility setting exists, while the displays themselves are flickering and actually triggering seizures in myself and others.

Additionally, if you are epileptic and have a high refresh rate external display, as it is recommended to use 100Hz or higher, but MacOS is delivering a signal to that display that is incorporating a 15Hz flicker from temporal dithering, that is no good.

Donux

brjdenis Elimination of flicker if this is what will be provided by Apple accessibility flags should be a very significant step towards resolution as well as increasing appeal of Apple products for wider customer base. But, it is likely, incremental improvements will be driven continuosly. I am sure, people have a lot of opinions on polarization, pixel layouts, backlight red phosphors, dimming technologies, screen glare etc. Also, screen is kind of the most important thing on the mac or macbook, it would be naive to think that Apple could not think about introducing their owm proprietory screen technology. It just they probably need to think also about various anti-competitive laws and regulations too. Vertical integration without very clear improvement and benefit to the consumers is a risky business I would think. But who knows, I am not a lawer. And maybe Apple is treating current panels as "good enough" and is focusing on the software.

JTL

anon123 macOS doesn't offer true 1:1 or 2:1 pixel-perfect scaling (even in 2x mode).

Been a while since I've used macOS but how is "native" 2x scaling imperfect?

AshX

anon123

I did mention integer scaling as one of the troubleshooting methods I attempted. But I am under the impression that by selecting the resolution that is actually half that of the native resolution, then you are actually utilizing “integer scaling” as @JTL indicated. This is different than pre-Retina MacOS.

My understanding is that MacOS will effectively perform a 2x zoom to achieve “Retina” quality. Everything else is fractional scaling which has suffered since Mojave, but especially since Big Sur. At the full resolution you’re just mapping the pixels 1:1 as you’ve described. I don’t really see much benefit to that unless you’re going to use the Tahoe accessibility options to enlarge the text significantly. I don’t believe the screens were developed with any sort of seriousness for most users using that resolution.

BetterDisplay utilizes anti-aliasing in most of its HiDPI scaling modes. This is why I purposely avoid fractional scaling both within the MacOS resolution section and also within BetterDisplay. Native is generally agreed to be the 2x resolution, and therefore proper integer scaling. All other modes utilize fractional.

Not everyone is sensitive to anti-aliasing and there’s a lot of overlap between dithering and dithering-related techniques, from what little I understand. I’m sure they will take into consideration all of this, including my questions about True Tone and Night Shift.

What will likely be more effective is being able select the color depth and therefore force 8-bit on the built-in displays. I don’t think there’s been much research on this forum on the relevance of most Intel MacBooks identifying a 24-bit framebuffer even on modern versions of MacOS. But I’d imagine that to be more relevant.

No clarity was provided as to what Macs, if any, are using 8-bit color. I have access to microscope footage that clearly shows FRC on a 13” M2 MBP Touchbar even when Stillcolor is running. Those machines are allegedly 8-bit “millions of colors” panels so either MacOS is sending a 10-bit signal and there is another layer of dithering or we are mistaken as to what the purpose of dithering ultimately is. Or it’s a 6-bit + FRC panel which I highly doubt.

anon123

JTL this is the discovery that @DisplaysShouldNotBeTVs made . and I can confirm it:

"My guess: in 2x-native mode on the physical display, macOS WindowServer itself is playing some kind of part in "scaling" BetterDisplay's streaming window because even if "1:1 pixel mapping" is checked the non-Retina stream will be the "correct" size of 13 inches. But in 1x-native mode, checking "1:1 pixel mapping" will shrink the 1280x800 1x stream to a quarter of the physical screen size (as would be expected).

This means that in 1x mode BetterDisplay itself is entirely handling the scaling the non-Retina stream back up to the full 13 inches of my m1air. What's certain about that is there's one less step of OS post-processing when set to physical 2560x1600 1x instead of physical 1280x800 2x.

My only guess is that there's some kind of really subtle additional smoothing that WindowServer adds via an additional Metal layer etc. (despite BetterDisplay integer scaling being enabled) that I'm sensitive to.

I usually can tell when things feel like they may just be placebo. In this case, I do NOT think this is placebo."

and these are the instructions for better display:

"create new virtual screen with aspect ratio as main screen
set virtual screen resolution to non-retina 1920x1080 1x
stream virtual screen to physical screen
in streaming settings under the virtual display menu, choose "Integer Scaling" (Important!)
set physical screen resolution to 3840x2160 1x (as in, the 1x res that usually would make everything extremely tiny)
go to "arrangement" in macOS display preferences and position your physical screen at the bottom left corner of the virtual screen (to prevent cursor from accidentally moving to it)
if your mouse pointer looks blurry, set a custom cursor color in display accessibility settings, after you close the color picker window and switch to a different app it will become clear again"

It makes a world of difference.

aydarms

AshX What is also interesting is why touchbar MacBooks do not have such a prominent gray flicker (that we can see on 240fps). Do you think that this gray flicker might really cause any health problems?

anon123

AshX

I think there’s a misunderstanding, I’m not talking about fractional scaling, only 2× (HiDPI).

Even in 2× mode (e.g. 1920×1080 “looks like” on a 4K panel), macOS is not doing true integer scaling in the strict sense.
Yes, the framebuffer is effectively 3840×2160, but:

CoreGraphics/CoreText use floating-point layout (no pixel snapping)
Glyphs are rasterized with antialiasing at subpixel positions
CoreAnimation compositing introduces blending/filtering

So the pipeline is still: vector → float positioning → AA → compositing

not: pixel-aligned raster → nearest-neighbor 2× replication

On Windows and Linux, when integer scaling is enabled (GPU or compositor level), you can get true pixel replication (nearest neighbor) with strict pixel alignment and no filtering.

macOS simply doesn’t expose that behavior even in 2× mode.

If you want a quick proof, try the BetterDisplay integer scaling + 1:1 pixel mode, you’ll immediately see the difference in how text and UI elements render

WhisperingWind

AshX

there is another layer of dithering or we are mistaken as to what the purpose of dithering ultimately is

I also think that Apple uses a mix of dithering algorithms. I was led to this conclusion by a post from aiaf, where he lists several patents from Apple, Samsung, and others.

Just to be clear: this is speculation based on public patents, not reverse engineering.

I think it's something like this:

FRC (patent JP4869422B2) - temporal dithering, which creates missing shades. For example, when we want to display a 10-bit signal on an 8-bit display.
Spatio-temporal rotation (patent CN102362307B) - a mix of spatial and temporal dithering. It's needed to eliminate banding caused by the interaction between FRC and pixel inversion on the display.
Dynamic dithering (patent US8860750B2) - temporal dithering. It doesn't increase the number of colors, but simply changes the rounding threshold from frame to frame. It's used to add pseudo-random noise to hide regular patterns, because FRC can produce visible grain and static artifacts on gradients.

Now here's the most interesting part: temporal dithering can cause flickering at 30 Hz and below. Therefore, (patent US9390690B2) suggests completely replacing it with spatial dithering in such cases. This patent may be directly related to the MacBook Pro with ProMotion.

Another interesting finding: even when an 8-bit signal is being displayed on an 8-bit panel, dynamic dithering may still be used. It doesn't add new colors, but it's very effective at reducing banding in gradients. So, just because the bit depth of the GPU output matches the bit depth of the monitor doesn't mean there will be no temporal dithering at all.

Of course, I don't know the exact implementation in the macOS driver stack - these are just interpretations of public patents. But they could show that dithering control on Apple's platform can be very complex and multi-layered - like a layered cake.

P.S. And now, a bit of reverse engineering. We also have the DCP controllers and the TCON controller, which each have their own settings regarding dithering. I suspect that on my MBP M1 13" there are two DCP controllers: dcp(for the internal display) and dcpext (for external display), which may also have different logic. Here's a screenshot from IORegistry on my M1 MBP 13" showing exactly that - dcp and dcpext are separate nodes in the device tree, both using the same AppleDCPExpert driver, but with different configurations and addresses. This explains the limitation of connecting only two displays to the MBP M1 13" - the internal one and one external.

AshX

aydarms

We can’t say whether gray color flicker is merely an artifact from 240 fps or whether it is a signifier of an actual problem.

I have LED lights that flicker on 240 fps and they’re completely comfortable. My entire analog car dashboard flickers on 240 fps and it’s fine to me. My iPhone 13 flickers like crazy and it’s fine to me.

The 13” M2 MBP and a Dell Latitude 5300 didn’t flicker on gray on 240 fps and they are both unusable for me. The 2011 Apple Thunderbolt Display didn’t flicker either and I couldn’t deal with it.

So I really don’t know whether it’s an issue or not. I don’t like the fact that the voltage seems so unstable on gray tones for Macs, but as users here and elsewhere have told me that’s fairly common to how LCDs work.

anon123

I can’t speak to this. More knowledgeable people like @aiaf would have to chime in. I was referring to scaling on the built-in displays. I know external displays are awful outside of very specific resolutions. My eyes are very used to high PPI screens so it’s the only reason I still bother with MacBooks.

I did notice the MacBook Neo was the first Apple Silicon Mac my eyes could easily focus on with font smoothing and GPU dithering disabled. Something about modern MacBooks has made a lot of the screens look blurry.