I went to hell and back trying to get PIP/PBP monitors on my 57" g9 ultrawide to work with my M2 pro. ended up having to use a powered hdmi dongle, displaylink cable, and displayport, with 3 virtual monitors via betterdisplay. Allowing resolutions outside of macs limitations setting in BD is what did the trick. I don't envy OP. Having 5120x1440 @ lodpi was the worst, just ever so slightly too fuzzy but perfect UI size but eventually got a steady 10240x2880 @ 120hz with HDR. I literally laughed out loud when I read the title of the thread. Poor guy.

Thanks, it was a good portion of my weekend bashing my head against the keyboard trying to figure out what was going on and if there was a workaround I could use (there isn't that I've found).

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. It was a mix of hardware limitations and the lack of options I had to address the resolution and refresh rates I had available over a Thunderbolt doc that I shouldn't have to think about.

I honestly hope they finally fix this. I would love it if they allowed sub-pixel text rendering options again too.

Yeah if I understand it correctly, this is more like 2160p@2x which is... unusual?

Yeah I'm not sure what the point of this article is really or am I probably misunderstanding something? There's no such thing as 4K HiDPI on a 4K monitor. That would be 2160p @ 2x on an 8K monitor. 4K at 100% scaling looks terrible in general across every OS.

Yeah. I don't get it. If you've got a 3840x2160 display, intended use on macOS as a 1920x1080@2x display, what is the advantage of using a 7680x4320 buffer? Everything is drawn at twice the width and height - and then gets scaled down to half the width and height. Is there actually a good reason to do this?

(I use my M4 Mac with 4K displays, and 5120x2880 (2560x1440@2x) buffers. That sort of thing does work, though if you sit closer than I do then you can see the non-integer scaling. Last time I tried a 3840x2160 buffer (1920x1080@2x), that worked. I am still on macOS Sequoia though.)

I don’t know why this was downvoted, I agree that this is a highly unusual configuration. Why render to a frame buffer with 2x the pixels in each direction va the actual display, only to then just scale the whole thing down by 2x in each direction?

Isn't that just 2x supersampling? If you want "perfect" antialiasing that's the minimum you need, no?

To be frank, it's kind of embarrassing if an entry-level Windows laptop with a decent integrated GPU handles this without much effort.

Apple is free to make its own choices on priority, but I'm disappointed when something that's considered the pinnacle of creative platforms sporting one of the most advanced consumer processors available can't handle a slightly different resolution.

In my case it's a standard LG UltraFine 4K monitor plugged into a standard 16" M5 MacBook Pro via standard Thunderbolt (via USB-C) - not sure what's not normal about this? I've confirmed it with other monitors and M5 Macbook Pros as well.

This is what us proles on third-party monitors have to do to make text look halfway decent. My LG DualUps (~140ppi if I recall) run at 2x of a scaled resolution to arrive at roughly what would be pixel-doubled 109ppi, which is the only pixel density the UI looks halfway decent at. It renders an 18:16 2304 x something at 2x, scaled down by 2.

It's also why when you put your Mac into "More Space" resolution on the built-in or first-party displays, it tells you this could hurt performance because thats exactly what the OS is going to do to give you more space without making text unreadable aliased fuzz, it renders the "apparent" resolution pixel doubled, and scales it down which provides a modicum of sub-pixel anti-aliasing's effect. Apple removed subpixel antialiasing a while back and this is the norm now.

I have a 4K portable display (stupid high density but still not quite "retina" 218) on a monitor arm I run at, as you suggest, 1080p at 2x. Looks ok but everything is still a bit small. If you have a 4K display and want to use all 4K, you have the crappy choice between making everything look terrible, or wasting GPU cycles and memory on rendering an 8K framebuffer and scaling it down to 4K.

I'm actually dealing with this right now on my TV (1080p which is where I'm writing this comment from). My normal Linux/Windows gaming PC that I have hooked up in my living room is DRAM-free pending an RMA, so I'm on a Mac Mini that won't let me independently scale text size and everything else like Windows and KDE let me do. I have to run it at 1600x900 and even then I have to scale every website I go to to make it readable. Text scaling is frankly fucked on macOS unless you are using the Mac as Tim Cook intended: using the built-in display or one of Apple's overpriced externals, sitting with the display at a "retina appropriate" distance for 218ppi to work.

Thank you

No, it didn’t get fully fixed.

Fucking with DP 1.4 was how they managed to drive the ProDisplay XDR.

If your monitor could downgrade to DP 1.2 you got better refresh rates than 1.4 (mine could do 95Hz SDR, 60Hz HDR, but if my monitor said it could only do 1.2, that went to 120/95 on Big Sur and above, when they could do 144Hz HDR with Catalina).

I would be absolutely unsurprised if their fix was to lie to the monitor in negotiation if it was non-Apple and say that the GPU only supported 1.2, and further, I would be also unsurprised to learn that this is related to the current issue.

I don't expect emails to get through to busy CEOs of huge companies like Apple unless you're really lucky and they make it through some automation, but I have dropped him an email just in case. I guess you never know.

I think you are probably right--it's a real problem.

As an article, it is not 100% coherent, but there is a valid data and a real problem that is clear.

Agree. I started reading the article until I realized it wasn’t even self-coherent. Then I got to the classic two-column table setup and realized I was just reading straight LLM output.

There might be a problem but it’s hard to know what to trust with these LLM generated reports.

I might be jaded from reading one too many Claude-generated GitHub issues that look exactly like this that turned out to be something else.

Apple doesn’t make an 4k external monitor.

They’re likely all on Studio Displays.

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

Tbh I'm not even sure what the issue is here. I have a personal M1 macbook and a work M4 and a 4k display. I don't see any issues or differences between them on my display. The M4 seems to be outputting a 4k image just fine.

The article could just be AI slop since it just contains hyper in depth debugging without articulating what the problem is.

Not in the Apple world, and this article is centered on Apple.

https://bjango.com/articles/macexternaldisplays/

  - 24" you need 4k
  - 27" you need 5K.
  - 32" you need 6k.

Windows subpixel aliasing (Clear Type) manages a lot better with lower pixel density. Since Windows still has a commanding market share in enterprise, you might be right about the industry standard for HiDPI but for Apple-specific usage, not really.

Thanks for the feedback, I'll try to take some photos, it's not an easy thing to do accurately without a good camera setup, but I'll reply here after work if I get something setup and added to the post.

It's in the environment and test setup (26.4 at the moment, but it is the same across all 26.x releases I've tried).

Their suggestion : get an Apple monitor that we just launched.

So MacOS supports only a handful of low dpi resolutions and high dpi must be an integer multiple of one of those?

32" 4k display at fraction scaling of 1.5 (150%) is fine for my day-to-day work (Excel, VS Code, Word, Web browsing, Teams etc.). It delivers sharp enough text at an effective resolution of 2560x1440 px. There are many 32" 4k displays that are affordable and good enough for office workers. I work in a brightly lit room, so I find that monitor brightness (over 350 nits) is the most important monitor feature for me, over text sharpness, color accuracy, or refresh rate.

For me it would be 16-27" 4k is fine, but and as you go up to 32" I'd be wanting 5 or 6k ideally as it's quite noticable for text (even when high DPI scaling is working and across operating systems).

I have dual 27" monitors, both at work and at home. At work, they're 4K monitors, because that's all they have in this size for some reason (LG if it makes a difference). At home, my own monitors are ASUS ProArt 1440p monitors. I run Linux in both places.

I really like my 1440p monitors at home more than the 4K monitors at work. At work, I'm always dealing with scaling and font size issues, but at home everything looks perfect. So I think you're onto something here: 1440p just seems to be a better resolution on a 27" panel.

Yup, 27" 4k with a Mac is truly awful. Don't do it. Get a 5k display.

If you actually care about this stuff you are going to run something like https://github.com/waydabber/BetterDisplay which easily allows for HiDPI @ 4K resolution, it does not "look bizarre" or "require fractional scaling". This is what the OP is about. I do the same thing, I run native res w/ HiDPI on a 27" 4K screen as my only monitor, works great.

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

what's a codeslave? I couldn't get it from the username.

I believe it will, it won't be until you push up to an 8k display that you'll get the old level of scaling back (could be wrong though as I don't have a way to test this).