I disabled dithering on Apple silicon + Introducing Stillcolor macOS M1/M2/M3

aiaf DISABLING "uniformity2D" WORKS

IT FIXES THE "weird fading to black bands around the edges" while still keeping bands on shadows (i.e. dithering is disabled TOO! this is in addition to it)

there is still some blotches of solid white backgrounds where changing gamma affects them differently than other areas of the same background, so that may be related to a different property, but uniformity2D is behind that weird edge effect!!!

the effects of disabling uniformity2D are sooooo obvious even when dithering is still enabled (but i can still notice an additional change when disabling/enabling dithering too)

this fixes something that's annoyed me about this screen for years where i always KNEW the edges were fading to dark instead of displaying a solid background

once you disable uniformity2D "you'll never unsee it" when it's on like it is by default! it's such a dumb screen effect because the screen honestly looks more color accurate when it's off!

in summary:

disabling and enabling dithering affects whether the fading to black at the edges (most visible on a white background) is banded or "smooth"

disabling uniformity2D GETS RID of the fade to black entirely

fyi:

a good way to test the effects of disabling and enabling dithering is looking at the transparent dark sidebar of Xcode against a wallpaper of a partly cloudy sky. you can easily see banding appearing and disappearing here

So after some more experimentation with the microscope, it turns out the OLED display I was testing Stillcolor with seems to have built-in FRC dithering. In fact, it is quite aggressive. The marketing and independent specification for the display make no mention of this. It occurred to me that I might be able to confirm that there is no temporal dithering built into the display by looking at the onscreen controls under the microscope. Sure enough, the middle grey design elements in the onscreen display settings have temporal flicker.

With that, I am more confident that Stillcolor is working on the M1 MacBook Pro 16". And that the temporal dithering visible under microscope might be LCD inversion with a sub-pixel implementation. But it amazes me how bad the LCD inversion is. The built-in MacBook display performs well on the many inversion tests available, but under the microscope it is pretty much terrible. If this flicker is LCD inversion, then I could see LCD inversion being a main cause of people's discomfort with these machines. I didn't know it was this bad, and had always thought this sub-pixel independent flicker under microscope on darker colors was temporal dithering.

Stillcolor does for sure increase the banding on the Lagom gradient test. So there is evidence it is working. It would be awesome to see time blend output from an M1 MacBook Pro 16" to a capture card, but for now I'll just have to assume Stillcolor is working. Because of the very similar noise of inversion, it is so far not obvious that anything temporal has been disabled by Stillcolor, through the microscope.

In the meantime, I am going to try to come up with an experiment to distinguish between LCD inversion and temporal dithering (sub-pixel type) to put this confusion completely to rest.

Blooey i still think the XDR Pros are dithering with an additional 10-bit to 8-bit FRC step like external monitors do (because macOS output is 10-bit but I doubt the internal panel is "true" 10-bit), and this would best be solved if Stillcolor gains the ability to truly force color depth

can you try measuring the display with both Stillcolor enabled and BetterDisplay dummy/virtual display mirrored to the physical display? BetterDisplay dummies try to render 8-bit (but I'm pretty sure the actual output of the Mac in the end is still 10-bit, until progress on forcing bit depths is made), curious if the flicker pattern changes with that configuration

DisplaysShouldNotBeTVs @aiaf in addition to the obvious change made by disabling uniformity2D DISABLING "NormalModeEnable" ALSO MAKES A HUGE CHANGE

( FYI, when disabling NormalModeEnable, make sure that ProMotion is off (use 60 FPS or lower.) Even though it also affects ProMotion, trackpad mouse cursor movement will get totally messed up, but this isn't an issue on 60 FPS and lower.)

after disabling:

at default gamma the screen will slightly change color tint and dark grays will get brighter

at darker gamma the screen gets A LOT brighter overall, and background colors look more solid

disabling it also makes shadows on windows feel less 3D (maybe because the level of backlight zones now becomes more similar between a dark window and a lighter background?)

AND on some pages, like the animation when you load the "MacBook Pro" page on Apple.com, there is even more banding after setting NormalModeEnable to false. (look at the white gaps between the laptops that are animating)

again, disabling this simply makes the screen BETTER, it removes another one of the strange tricks used to mask the imperfections(?) of the display, potentially this one is related to control of the mini-LED backlight zones?

this image on Apple's website implies that typically mini-LED zones will have different brightness per zone that attempts to match whatever image is being shown?

potentially this property reduces or disables this?

there are still some blotches of (now not dithered anymore) gray on white backgrounds visible at lower gammas, but we're just a property away from clean screen output (aside from forcing 8-bit which is also important), i can feel it

So far:

enableDither = false: way less text shimmer, can more easily visually process multiple occurrences of a repeating object at once, edges of "pixel-perfect" icons in Finder list view look sharper

uniformity2D = false: the "vignette effect" / fade at edges is GONE

NormalModeEnable = false: less "cloudy", more natural color tint

both uniformity2D and this potentially reduce the weird "fake 3D" effect

The issues that remain:

"Fuzzy text/glowing halo around text" (may be related to panels from one of the multiple manufacturers only, based on prior experience since one friend's Mac didn't have this issue), some shimmer on certain background colors, blotches of slightly different shades on solid backgrounds (that are very obvious now because they can't "blend in" by being dithered)

@aiaf do you have any pointers for being able to use IOKit in Swift on iOS so I could experiment with adjusting enableDither on my iOS devices? IOKit is a private framework on iOS and gives an error when trying to import it with IOKit.

Some people said they could use it through Objective-C instead, but I don't know how to write ObjC at all (despite me being very experienced with Swift). However, even when trying to do this just to see if it would work, I actually couldn't get IOKit to load in ObjC either.

———

FYI: As I am a mobile developer, I have a LOT of iOS devices I've collected over the years… so I can certainly help with testing anything iOS-related if this ever becomes something you're interested in.

For reference:

Devices I own with "good screens": iPhone 4 (iOS 7), iPhone 5 (iOS 6.1.3 native, but also runs iOS 7/8 via dual boot), iPhone 6 (iOS 12), iPhone 7 (iOS 15), iPad mini 2 (iOS 10.2), iPad 6 (iOS 15)

Devices I own with "bad screens": iPhone 5s (iOS 12), iPad Pro 11" 2018 (iOS 17), iPhone SE 2 (iOS 17.2.1), iPhone 14 Pro (iOS 16.4)

DisplaysShouldNotBeTVs Update: I'd recommend only disabling dithering and uniformity2D — as disabling NormalModeEnable seems to make the system less stable / cause the cursor to lag / eventually randomly crash the WindowServer and log out.

Disabling the other two, dithering and uniformity2D, works totally fine and that does most of the work in improving the screen, so disabling normal mode isn't that necessary.

I'm still not sure which property will get rid of the "blotches of slightly different colors".

I wonder why disabling NormalModeEnable is causing this?

@aiaf just found AN IMPORTANT ONE

Disable VUCEnable

This causes even more banding to appear on the gradient test than just disabling dithering on my M1 Max XDR.

Additionally, "irregular patterns of boxes" appear on certain solid color background shades.

Potentially this is disabling the internal panel's FRC???

If you turn the Mac backlight up to max and Software Brightness (BetterDisplay) very far down, you will also now see a "dark, heavily banded blotch that follows the mouse cursor like a trail" when moving the mouse on a dark gray background. (Easily seen after zooming in with Ctrl+Scroll accessibility zoom.)

This confirms another thing I swear I could see for years, where it always felt like there was a dark spot around the mouse or that there was an area flickering around the mouse (specifically on the internal display). There IS, and it was literally being dithered (i.e. flickered) to hide it, too.

This will also make a strange "animation" visible (that was present before but now very obvious) of all the "blotches" I've pointed out moving around whenever Software Brightness is changed, lagging behind a second or so with what seems like an intentionally smoothed out animation — even when BetterDisplay's own "software brightness smoothing" is disabled.

I still don't know how to disable these blotches, but one thing's clear — they're basically programmed to "move around in the corner of your eye at a slower, smoothed out rate compared to everything else" whenever colors change on screen. And before enableDither=false, uniformity2D=false and VUCEnable=false, the effect was being dithered very aggressively in order to "hide" whatever this is.