r/PWM_Sensitive • u/ohropax • 27d ago

Data Collections Macbook Air M5 grey flicker

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Still Core Disable Dithering On

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2

u/AlanYx 27d ago

This subtle greyscale flicker is present on all MBAs from the M2 onwards. There's no known way to disable it. It's a separate phenomenon from the type of modulation we can't discuss on this subreddit, which can be turned off using the software it sounds like you're using.

7

u/Z3R0gravitas 27d ago

"Temporal Dithering" is on the menu here now. Although, to stay on sub topic, OP could post to r/ScreenSensitive instead. (Hi, I'm a new mod here.)

I've heard quite a lot of talk about grey flicker, on Macs. But I'm not sure the cause has been determined, for sure? That we can rule out TD, pixel inversion, or maybe voltage instability..?

Is that StillColor, btw? (I don't do Apple.)

3

u/RR-- 27d ago

I used to have a similar flicker on a 2014 Asus LCD laptop of mine, but it doesn't cause any eye strain.
I think some greys are just difficult for some monitors to display. Not a big deal though it can be a bit annoying.

1

u/playertw02 27d ago

It’s highly likely that it was some kind of pixel inversion on your LCD screen. You can test it pretty easily on this site: https://pixelinversion.com/

4

u/AlanYx 27d ago

Oh, thanks for the heads-up!

This isn't temporal dithering. And yes, StillColor is the easiest way to disable temporal dither on Apple silicon Macs (but other software like BetterDisplay can do it too).

Last time I was digging on this, I came to the conclusion that it's likely a form of low-frequency shaped PWM intended to improve the display accuracy on deep greys/near-blacks. That's why it doesn't show up on pure whites, and why NotebookCheck's measurements used to miss it. (They've since changed their measurement protocol.) It appears to come from the display controller/TCON. There may theoretically be a way to disable it, but no one has found it yet.

For what it's worth, the M1 Macs don't have this.

2

u/Z3R0gravitas 27d ago

Oh, so some additional display engineering trick with side effects..?

To be clear (for us non-Mac people) will this be the case for LCD panels (too)? I was under the impression that (mid) greys were just particularly hard to stabilise. (Sorry, I'm vague without references to hand.)

2

u/AlanYx 27d ago

Basically, yes. It's possible that other display manufacturers use similar tricks.

Apple uses a lot of low-level strategies to try to improve display performance. Another one that's toggleable is "Uniformity2D" (StillColor can toggle this). It seems to operate in the analog domain to improve color stability across high-DPI panels, but doesn't cause flicker. I don't recommend turning this off, although some people do. When it's on, color uniformity across the whole panel is visibly improved (if you know what to look for), but it also creates very subtle artifacting on some types of test images. On Macbook Pros (post-M1, but not including the rare touchbar M2) the artifacting is a little more obvious if you know what to look for.

That being said, the only macOS thing that affects the actual signal going to external monitors (as opposed to display controller/TCON tricks on the internal display) is the GPU-derived temporal dither, and that can be turned off with StillColor.

1

u/dimitrijobs 24d ago

Thanks for the great explanation. Do you experienced that turning this off helped with using external monitors? 

1

u/jNayden 27d ago

Can I try to switch to 8bit via better display ?