Dither frames are temporal frames in which individual pixels color value are made to alternate over time. Another term used in the display industry is called periodic frame alternation.
Generally speaking, the higher the number of dither frames, the higher is the number of flicker variations. Some flicker variation are less perceivable. While some ~ are provocative.
For instance, we have a 120 hertz refresh rate panel with 2 dither frames using TD. Within a 120 hertz refresh, there are a total of 120 cycles. Similarly, a 60 hertz refresh has a total of 60 cycles.
2 dither frames would mean within every 120 hertz refresh, a selected amount of RGB subpixel will have its time ON in frame 1, while the other remaining half on dimmed in frame 2. In the following cycle, in frame 1 where the subpixels that formerly fully ON are now dimmed, while those in frame 2 are now on fully ON.
As brought up previously in another post on the similarity between PWM and TD — where both share a similar concept of frequency and amplitude modulation metrics, TD/ FRC uses dither frames to make up its duty cycle.
This is in contrast to PWM's duty cycle where it uses time to determine its percentage of screen ON time.
The following figure illustrates the alternation in subpixel between frame 1 and frame 2 as mentioned above.
Red line to red line is per cycle within 120 hertz. In 120 hz, there are 120 cycles.
Assuming that in frame 1 the subpixel blue is at blue(184) value and in frame 2 subpixel blue is at b(183) value, and on the next cycle frame 1 subpixel is on b(183) and and frame 2 subpixel is on b(184) — we know that this is a 50% dither duty cycle. Since for that subpixel, it displayed the higher pixel value blue(184) on frame 1 and not on frame 2. Furthermore, there are only 2 dither frames.
The formula is determine dither duty cycle is as followed:
Dither duty-cycle = (Higher pixel value / total number of Dither frames) X 100
Following so far?
Perhaps we can use HDR (that can use TD algorithms) as an example. Typically, it can go up to 4 dither frames.
Assuming that it is using 4 dither frames, and 2 of the frames are identically on ON, while the remaining 2 are exacts of the remaining alternates. This is again, a 50% dither duty cycle and resembles the example of 2 dither frame mentioned earlier.
Why 50%? Because~
Dither duty-cycle = (Higher pixel value -> 2 exacts frames / total number of Dither frames -> 4) X 100
Thus, We have 50% duty cycle.
However, if there is only a frame on fully ON, while the rest of the 3 frames dimmed, this is a 25% duty cycle.
What if all frames are on fully on? Then it is a 100% duty cycle. No pixel flickering from TD or HDR. It is as good no TD algorithms used.
Below is an example of 5 dither frames with 100% duty cycle.
Moving on to FRC (spatiotemporal dithering)
This is where it gets interesting. Since they are usually + 2bit by default — we can infer that it is using 4 dither frames.
Note: In 1 bit there are 2 dither frames. 2 bit is 4 dither frames. 3bit is 8 dither frames. 4 bit is 16 dither frames. You get the idea. Basically, just use 2 ^ (bit number)
In FRC, frames within the dither frame typically do not remain the same. Since its objective is to blend different subpixel colors to give you a new color shade. The second interesting aspect of FRC is that it can run up to 15 dither frames, regardless if your panel is a 2bit FRC. As afterall, 2bit FRC just means the minimum color depth it can provide, and not the maximum dither frame it can reach.
I spoke of FRC while at its worst, can enable subpixel color flickering at a mere 8 hertz before. Here I am going to share how to obtain the dither frequency.
Assuming your panel decides to be a little nasty and do a 15 dither frame, with each frame vastly different from the other. But wait firstly ~ below is the formula to calculate Dither frequency at its lowest possible duty cycle.
Lowest Dither Frequency = Screen Refresh rate / total number of Dither frames
Since we know our screen refresh is 120 hertz, and it is using 15 dither frames, we get a result of 8 hertz by dividing 120 with 15.
Now, this 8 hertz is the result of the duty cycle with 1 unique frame out of 15 different frames. If there are 8 exact frames instead within the 15 frames, duty cycle is now at 53%, which is approximately at 64 hertz (take 8 hertz times 8 frames). This is not as big of an issue as compared to the 8 hertz which has about 6% duty cycle (refer to dither duty cycle formula above).
Below is an example of 5 dither frames, which is quite common in +2 frc. Here we can see that at every cycle each frame is different. Thus, this is a 20% duty cycle (1/5 x 100). Within each unique frame, it will have to skip 4 other cycles before it is back fully ON again. Hence, the hertz is:
Dither frequency = (screen refresh)120/ (dither frame)5 = 24 hertz.
24 hertz per subpixel channel is arguably low for a panel we are staring directly into.
If we add amplitude depth into each subpixel color it adds an additional layer of complexity and complains. For instance, we have Blue subpixel going from Blue(184) to Blue(0). That is a PWM-level of strobing.
Why it matters
According to research, our retina cones (the individual RGB receptors) has a critical flicker fusion threshold of over 30 hertz[1].
Approx. 36 hertz threshold while on 30 nits and up to 47 nits on higher brightness.
Furthermore, among the red, green and blue receptors, blue receptors are the most sensitive, followed by green and lastly red receptors. In another study on individuals with a heightened sensitivity to light, they found that blue and red light are equally symptomatic, with green being less problematic. A Japanese study also found increased complains of symptoms with certain spectrum of red light, as opposed to red and blue light.
Lastly, in a study conducted by Human Factors NASA Ames Research Center, they argued that even when the (generally accepted) industry standard for FRC(spatiotemporal Dither) blending of subpixel color frames is flicker free between 15-20 hertz, each dither frames' luminance has to be in balanced. Else, the combined result of the blended frames(120 hertz) luminance flicker can also be perceived even outside the highest critical flicker fusion threshold of 60 hertz.
With the above studies, one can draw assumption that a display should keep the subpixels flickering and blending of frames above the recommended 30 hertz threshold. Each luminance intensity within each dither frame has to be consistent to reduce visibility of flicker.
Source:
[1]Chapiro, A., Matsuda, N., Ashraf, M., & Mantiuk, R. (2023). Critical flicker frequency (CFF) at high luminance levels.
[2]Mulligan, J. B. (1993, May). Methods for spatiotemporal dithering. In SID International Symposium Digest of Technical Papers (Vol. 24, pp. 155-155). Society for Information Display.
Temporal refers to "time-based". While PWM flicker (a macro-level temporal light modulation) and Temporal noise flicker (a micro-level temporal light artifact) are imperceivable to the naked eye, they can still affect sensitive individuals cognitively, causing symptoms such as headaches, blurred vision, and disorientation.
The following common temporal noise techniques used in our interactive displays that have affects users are:
These micro flickers been mentioned in various studies and research. A few researchers have proposed different solutions to mitigate its undesirable flickering effects.
It is important that we do not advocate the cease of use for devices that have been suggested to employ the above. Our objective is to investigate device that use safe temporal noise optimisation that brings little to no impact to our health.
The second primary objective is suggest available settings for other users to change, in order to mitigate the impact of temporal noise flicker artefacts on us.
This brings to the next point.
Why the need to investigate safe temporal noise optimisation over blanketing a technique as good/ bad.
A few in the community may have come to think of dithering as an absolute health concern. However, that is not always the case.
There are instances where dithering is used to reduce flicker resulting in increased eye comfort experience.
For instance, flicker from Transistor Leakage Current has always been the biggest challenge for display engineers. A good example of recent devices which suffered from this bad flicker are some of recent Motorola LCD phones.
Typically, the quickest workaround to Transistor Leakage Current is to use spatial dithering to lower the intensity of each backlight flicker.
Spatial dithering is the use of turning off certain pixels in order to show more of dark grey and less bright grey levels. Once they were off, they do not flicker. This is in contrast to temporal dithering where pixels flicker stationarily.
The disadvantage to spatial dithering is that it would result a decreased sharpness because a number of pixels were turned off. I believe this goes against Motorola's intention of having a bright and sharp screen.
Some display panels faced restriction in seemless brightness adjustments. For instance, the transistors were only about to adjust in brightness steps of:
5%
-
20%
-
35%
-
50%
-
75%
-
90%
-
100%
Thus, display engineers can opt to have the display flicker in order to regular in the between brightness. While they can have the entire flicker vigorously, they can also use a DC-dimmed spatial dithering hybrid to achieve this.
5%
- spatial dither
20%
- spatial dither
35%
- spatial dither
50%
- spatial dither
75%
- spatial dither
90%
- spatial dither
100%
The success of each implementation is largely dependent of the implementation, rather than whether has it used dithering.
Available Readings:
• A Comprehensive Analysis of Dithering Algorithms and GPU Implementations
So i bought two of these phones for two friends of mine due to their good specs for a low price (8gb/256gb/decents camera and miravision? mediatek cpu for €160).
They've not yet had time to spend a lot of time on them,
but when I did the updates on those phones and took the time to get to know all.the twerks and perks...
it quickly became obvious that it causes eyestrain almost bad as oled.
Checked for pwm with camera, nothing.
Zoomed in with my camera on the pixels, couldn't see them.jumping around so I suppose there is no dithering.
Even when i am on my pocophone with awesome ips screen, but the moto g56 is in close proximity laying on its back... screen pointing upwards not at me: its causing eyestrain symptoms.
So.i do not even have to directly look at the screen. Looking at the light emitted by it is enough to cause eyestrain symptoms.
Turning off hardware acceleration to force GPU stops the nausea, but doesn't stop the eyestrain.
I think the eyestrain was less pronounced before updating to the latest android version.
Feel.sorry for them having to look at such a shitty screen but i figure they will probably not be sensitive, idk.
Sono bloccato su iPhone 8 da diversi anni oramai, non volendo abbandonare l’ecosistema Apple, per via dei nuovi display OLED e del TD. Ho provato in questi giorni diversi modelli per tentare un aggiornamento: iPhone XR e iPhone SE (iOS 26). Entrambi mi causano fastidio agli occhi.
Non ho trovato discussioni recenti a riguardo. Come state risolvendo? Purtroppo anche lato computer sono bloccato su un MacBook Pro 2015.
months ago i made a post in which i complained about buying a refurbished iPhone XR on iOS 18.7.5 - buying it because of its smooth pixels and graphics which made it comfortable for me.
A user states the 'blurriness i saw' was just a casual behavior due to a malfunctioning of how iPhones treat dithering when they are restarted.
I honestly think the sudden disappearance of that extremely fine graphic pipeline may be due to a "security and system file update", but none of the two theories can be proved, unfortunately.
Out of desperation, i tried to downgrade it to the second last signed iOS version (at the time iOS 18.7.4), but it messed up, i was close to bricking the phone and i only recovered it via iTunes, which forced me to upgrade to iOS 18.7.7.
for about two months i stayed on my Xiaomi 11T on Hyperos 1.0.19 (EU) with dark mode, reading mode at its maximum , color combination set to red, and greyscale, but most importantly:
i used to switch from using Twilight with like 90% darkening and system brightness at 100% (a sort of 'forced reduce white point')
to just disabling twilight and lowening system brightness. (but always keeping greyscale)
Anyway, by the end of April the sharpening on the objects, lights and everything had begun unbearable anyways and i always felt the urge to throw up.
TRY THIS IF DOUBLE INVERT TRICK DOES NOT WORK
So i picked up again my iPhone and i tried to enable, for the second time, the 'double invert trick' along with greyscale and it seemed a big relief in that particular moment, i dont know why, but - as you will see in the next paragraph - there are things that can mess up, so it's far from optimal, but going back to Xiaomi 11T means constantly feeling like i'm gonna throw up.
Anyway, this unique method does not always works out.
It might worth try this procedure if you are still struggling
Re-do the official procedure if you have already done it, but BACKWARDS this time
(optional) you might wanna restart the phone
Classic Invert ON
Smart Invert ON
You will see the Classic invert will automatically disable, that is absolutely normal.
Use the phone in this state for 30 seconds / 1 / 2 minutes.
Then disable the Smart Invert and follow again the official procedure in the link above.
You should know it is working when you see a sort of soft dark blue light spectrum in the background or when moving the phone to the side
THINGS THAT CAN MESS UP
Anyway, there are still things that can increase dithering and mess me up. From stupid things - like setting a generic DNS profile from the Internet or just changing something in the settings, like messing with the text or even it seems removing widgets or even 'turn off intense audio' - to even create a custom ringtone via 3utools, even if these last things sound totally insane.
When this occurs all you can do is reset all the settings (not the hard reset) and re-do the procedure. Maybe it will not be optimal, but "less worst" than other devices. indeed im still on this iPhone.
THERE IS STILL A LOT OF DITHERING
in every sort of text and in apps like Instagram, which is the worst.
THE BIG ISSUE WITH THE DOUBLE INVERT TRICK AND MY NEW CRY FOR HELP
The big issue with the double invert trick is that for some unknown reason it does disable REDUCE WHITE POINT WHICH IS ESSENTIAL FOR ME as a visual snow sufferer, i am very sensitive to blue light and light in general. I still feel the urge to throw up and like something is severing my eye nerves - and cracking my head, jaw, ears and so on.
Are there any workarounds for this??
i'm gonna try a blue light-proof film from an Online Store, but i'm very skeptical about it.
Any advice or thought is appreciated.
Thanks for reading.
Ever since upgrading my iPhone 11 (LCD screen) from iOS 17 to iOS 26, I’ve developed eye strain, slight dizziness/off-balance feelings, and tingling in my head while using the phone. I have zero issues using TVs, MacBooks, or other digital screens — only my iPhone. I’ve found some relief using accessibility settings including Night Shift (warm setting), Reduce White Point, Display Zoom, and the “Classic Invert + Zoom filter” trick. I also noticed symptoms flare badly in dark rooms or after bright flashes. What’s strange is that when I wear blue-light blocking glasses, my symptoms completely disappear almost instantly.
I’m trying to figure out whether this is related to temporal dithering, display rendering changes in iOS 26, contrast modulation, or something else software-related. Has anyone else experienced this specifically on LCD iPhones after updating iOS? And has anyone found a long-term solution besides constantly wearing blue-light glasses or downgrading devices?
I have been using TCL 10 5G wirth Android 11 several years without any issue. The phone is not getting OS updates anymore. After update of Google services and Chrome and some apps (Keep...) I started having eye strain. Text in UI of some apps looks like bad Clertype.
Is it possible that this is caued by update of Chrome rendering webview and/or new version of Google Services?
We recently received new monitors at work, but unfortunately I’m unable to use them because they appear to use flickering technologies such as Temporal Dithering (TD/FRC). Despite the monitors carrying a TÜV Rheinland certification for being “eye-friendly,” they still cause discomfort and symptoms for people like me who are sensitive to these technologies.
What makes this especially frustrating is that I seem to be the only person in my workplace affected by these new ultrawide monitors. Because most people can use these displays without issues, manufacturers may continue choosing these cheaper display solutions without realizing that a smaller group of users experiences real symptoms from PWM and TD/FRC technologies.
I wanted to raise awareness about this issue and encourage TÜV Rheinland to also take TD/FRC sensitivity into account when evaluating eye comfort certifications. There are more people affected by this than many realize.
I also encourage others who experience similar problems to speak up and contact manufacturers and certification organizations, so our voices can be heard.
I am considering buying a used HP EliteBook 855 G7 with an AMD Ryzen processor.
The hardware ID of the screen is AUOA08B, which according to Panelook points to the AUO B156HAN09.1 (60Hz, Low Power, 400 nits, native 8-bit). However, Panelook also mentions a PWM frequency of "Min. 200Hz ~ Typ. 1KHz ~ Max. 10KHz". On the other hand, reviews and tests claim it is PWM-free.
Does anyone here have real-world experience with this specific laptop/panel or this generation of HP EliteBooks? Does the AMD graphics card enforce aggressive temporal dithering on this native 8-bit panel? If needed, I plan to disable Vari-Bright and use tools like ColorControl or ditherig to force a stable 8-bit output.
Any insights or measurements regarding eye strain on this setup would be greatly appreciated. Thanks !
I was very upset because not being able to use My PC without headache and eye pain, I read about being Windows 11 all the problem and tried to down grade to Windows 10 without any benefit, later on I hapend to realice that wasn't My OS or My setup (screen being 6 bit +FRC) but a lamp at my desk that has an awful cheap LED bulb, I soon as I turn it off I got relief, by the way my room is pretty dark I needed another source off light not only the light that comes through my window, anyway I will replace that bulb
Well because my computer had a screen update/driver update at work I can no longer use the pc I've been using fine for years.
They are struggling to find a solution for me and are saying they won't roll back the screen update.
It's very likely I'm going to lose my job over this. I'm so sick of having this sensitivity. It absolutely is a disability, software developers and companies need to take note that this isn't fair and they have to stop allowing this type of TD without a way to turn it off for people that have a disability/sensitivity to it...
