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New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

smcleod.net

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Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#91

Post by mkl »

compounding_it wrote: post #35

The ideal work/coding resolutions and sizes for macOS that I would suggest if you are going down this rabbit hole. 24 inch 1080p 24 inch 4k (2x scaling) 27 inch 1440p 27 inch 5k (2x scaling) 32 inch 6k (2x scaling) Other sizes are going to either look bizarre or you’ll have to deal with fractional scaling. Given that 4k is common in 27/32 inches and those are cheap displays these kinds of problems are expected. I hav…

27" 4k is totally fine on Windows 11 (not a gamer). Everything is sharp at 150% scale.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#92

Post by wpm »

TheTon wrote: post #68
wpm wrote: post #47

Earlier quoted context omitted.

Because 1x mode has no subpixel antialiasing and thus looks absolutely terrible. I have a 32:9 Ultrawide I would love to use on macOS but the text looks awful on it.

Then complain about that. That would make a much more sensible blog post and discussion. Asking for a crazy workaround to a sane problem isn't a great way to get good results, especially with Apple. Beyond the obvious performance pitfall, this scale up to scale down approach will also destroy the appearance of some controls. There is some UI that aims for 1px lines on hidpi modes that will get lost if you do this. It…

The crazy workaround only needs to be done because of what Apple did probably around a decade ago and probably already heard a bunch of crying about and didn't care. No one removed subpixel antialiasing on their own, we do this bullshit because Apple forced us to to make text look halfway decent.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#93

Post by extr »

nuker wrote: post #7

Send it to Tim Cook email. It worked for me fixing DisplayPort DSC bug. After Catalina, later MacOSes lost ability to drive monitors at higher than 60Hz refresh. Apple support tortured me with all kinds of diagnostics, with WontFix few weeks later. Wrote email and it got fixed in Sonoma :) https://egpu.io/forums/mac-setup/4k144hz-no-longer-available...

Just emailed him. Ridiculous issue.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#94

Post by dostick »

wronglebowski wrote: post #2

Props to the author for putting in what looks like ton of work trying to navigate this issue, shame they have to go to these lengths to even have their case considered.

The post reminded me how I investigated a similar issue having no idea. Using Claude or GPT to investigate this kind of hardware issue is fast and easy. It gives you next command to try and then next one and you end up with similar summary. I wouldn’t be surprised that author didn’t know anything about displays before this.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#95

Post by whatever1 »

robertoandred wrote: post #27
whatever1 wrote: post #13

How did none of the Apple devs notice this? 4k 32" inch is the industry standard for HiDPI monitors.

Don’t think I’d call 4K at 32” high dpi.

I agree with you. It's my IT who disagrees.

But to be fair, until last year there were no retina monitors in the market except the Apple ones. In 2025, the tides turned, there are now way more options both for 5k and 6k retina displays.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#96

Post by petersellers »

smcleod wrote: post #90
petersellers wrote: post #81

Earlier quoted context omitted.

In macOS display settings, what scaling mode are you using? This bug appears to only affect 4K monitors that are configured to use the maximum amount of screen space (which makes text look uncomfortably tiny unless you have a very large monitor). Most people run at the default setting which gives you the real estate of a 1080p screen at 2x scale, hence the "not normal" part of this configuration. Actually, I don't ev…

If you use the middle screen scaling you're given absolutely huge UI elements and it's the case for the inbuild 16" screen as well as external displays but when you get up to 32" displays it's almost comical how large the UI is on the middle / default setting.

Yeah, on larger monitors it's more common to run at the monitor's native resolution without scaling but even so macOS will not turn on HiDPI mode - you'd still need to do this explicitly via another app (I didn't even know it was possible to turn on HiDPI mode at native scaling until reading this article)

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#97

Post by mono442 »

tgma wrote: post #89

This might be a dumb question: Is the author looking to run 4k display at HiDPI 8k framebuffer and then downscale? What's the advantage of doing so versus direct 4k low-DPI? Some sort of "free" antialiasing?

That's exactly what he is trying to do. It's really just because MacOS has bad text rendering when graphics aren't rendered at 2x scale.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#98

Post by Sir_Twist »

NBJack wrote: post #40
skullone wrote: post #3

I thought I was going crazy when my new m4 seemed "fuzzier" on my external 4ks. I tried replicating settings from my old MacBook to no avail. I wonder if Apple is doing this on purpose except for their own displays.

It's a bit nit-picky on my part, but this bizarre world of MacOS resolution/scaling handling vs. other operating systems (including Windows 11 for crying out loud) is one of my biggest gripes with using Apple hardware. I remember having to work hard to make my non-Apple display look 'right' years ago on an Intel-based mac due to weirdness with scaling and resolutions that a Windows laptop didn't even flinch handling.…

https://news.ycombinator.com/item?id=17477526

This reminds me of this comment, which I feel is a somewhat unsatisfying explanation, given that despite these difficulties, Windows somehow makes it work.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#99

Post by LarsAlereon »

tgma wrote: post #89

This might be a dumb question: Is the author looking to run 4k display at HiDPI 8k framebuffer and then downscale? What's the advantage of doing so versus direct 4k low-DPI? Some sort of "free" antialiasing?

From what I understand, the main goal is to fix the problem that non-native (1:1 pixel mapping) resolutions and scaling look worse than native. This is a problem when you ship high-dpi displays that need UI scaling in order for things to be readable. Apple's solution was to render everything at a higher, non-native resolution so that images were always downscaled to fit the display.

So to oversimplify, Windows can have a problem where if you are running 1.5X scaling so text is big enough, you can't fit 4K of native pixels on a 4K display so videos are blurry. If instead you were rendering a scaled image to a 6K framebuffer and then downscaling to 4K, there would be minimal loss of resolution.

Re: New Apple Silicon M4 and M5 HiDPI Limitation on 4K External Displays

#100

Post by smcleod »

arjie wrote: post #22

I'm sure you've already given this a crack via some other technique (I just Cmd-F for it and didn't find) but I have had monitors with confusing EDIDs before that MacOS didn't handle well and the "screenresolution" CLI app https://github.com/jhford/screenresolution always let me set an arbitrary one. It was the only way to get some monitors to display at 100 Hz for me and worked very well for that since the resolutio…

Hey, thanks I hadn't tried screenresolution but that seems to simply set the resolution and refresh rate without controlling the scaling which is what is needed for configuring the HiDPI mode scaling.
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