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Comment by tom_ | Hacker News Reader

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.)

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> 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?

Text rendering looks noticeably better rendered at 2x and scaled down. Apple's 1x font antialiasing is not ideal.

Especially in Catalyst/SwiftUI apps that often don't bother to align drawing to round points, Apple's HiDPI downscaling has some magic in it that their regular text rendering doesn't.

Feels like a huge power loss just to get slightly better text. You slow rendering down 4x for this

Yes but Apple got to drop subpixel anti-aliasing support because this workaround is "good enough" for all of their built-in displays and overpriced mediocre external ones, so we all get to suffer having to render 4x the pixels than we need.

So, how do I actually set this for my Mac, or is this something which each application may or may not do?

There are third party tools like BetterDisplay that unlock it as an option https://github.com/waydabber/BetterDisplay

Apple’s 1x font antialiasing is not ideal because it no longer exists.

They still use antialiasing, just not sub-pixel antialiasing.

Yes 1920x1080@2x absolutely works on M4. I use this mode all day every day.

Yeah that would work, that's just 2k HiDPI, not 4k HiDPI.

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