Yes, macOS renders a full image in a virtual buffer to 5K, and then (as good as) halves it.
No, it doesn't. You keep saying that you understand and then repeating the same mistake.
There is no halving of resolution involved. MacOS renders a 5k3k image and sends that to the display. The system UI elements are rendered double-sized
but are still rendered at full 5k resolution. On a 220ppi display that scaling is
needed to make them usable.
There's only an extra scaling step if you choose a mode other than "looks like 2560x1440" or "5120x2880" - in that case the internal rendering is to twice the "looks-like" value and that's then downsampled to the native resolution of the screen. With a 4k display, many people will run in "looks like 2560x1440" mode to get their preferred UI scale, in which case the image is rendered internally to 5120x2880 and then downsampled by the GPU to native 3840x2160 (which introduces scaling artefacts - but still displays more detail than an actual 1440p display)
Exactly, very view people who can see that on such a small monitor. So what you get is huge disappointment.
You have fixated on the idea that doubling the (linear) resolution should double the "real estate". It doesn't. The point of "retina" was always sharpness & making pixels too small to notice.
MacOS has
always been designed around the idea of a fixed pixels-per-inch scale (back in the 80s it was 70ppi so 1 pixel = 1 point, today it's ~110ppi for "standard def" and ~220ppi for "high def/retina" - I think there's support for 330ppi in MacOS/iOS, too, probably in anticipation of 8k). The "Apple" way has always been that, to get more screen real estate, you buy a larger screen with the same pixels-per-inch.
A major selling point of 5k3k @ 27" displays - and why Mac users are prepared to pay a premium - is that 220ppi resolution giving what many people see as the "optimum" UI size for MacOS at comfortably-better-than-retina sharpness.
Like in if someone came from a 2560×1440 monitor, they still have the same amount of space.
Yes.
That's part of the point of 220ppi displays. The UI size of the old 1440p iMac is widely seen as "perfect" for MacOS - and the fonts and buttons were already pretty space-efficient c.f. other OSs. making them smaller would reduce usability.
The other advantage of 220ppi displays is that -
if you don't like the UI scale - they can be used in fractional-scaling mode to give you several intermediate choices between "looks like 1440p" and "native" - and the higher native ppi means that the scaling artefacts are less prominent than you'll see on a 4k screen.
...which many people will find unusable on a 27" display because the system fonts, buttons, controls etc are too small for comfort.
But - as you've shown - a 5k3k display will quite happily run at straight native resolution if that's what you like. (I think you have to option-click on "Scaled" and/or install something like SwitchResX to get the choice). If you want to define "real estate" as how much you can fit on the screen in native mode (usability not an issue) then a 5k3k display will still have more real estate than a 5k2k or 1440p display of comparable size - in which case, what is your point?
Reality at the moment is that there are approximately zero 5k3k displays with larger-than-27" screens (there aren't that many 5k3k options full stop) - which is what people would actually need to make "native mode" usable.
Retina on the same screen:
Which is
probably how the app designer intended it to look if it was designed for Mac. If the UI design wastes space on the screen format used by the iMac for the last decade then complain to the designer.
I've found that cross-platform stuff designed with PC in mind tends to target multiples of 1080p and is more screen-efficient on Mac (e.g. Affinity, VS Code) - or there are things like Blender which have independently scalable UIs.
Now, on 4k displays there
is a dilemma: "looks like 1080p" with 2:1 UI scale makes the UI about the right size for a 24" display (and, sadly, 24" 4k displays seem to be dead) but it is rather space-consuming on a 27" or larger screen, while "native" 3840x2160 without UI scaling is too small for most people on anything smaller than about 30". That's why most people judge 4k by fractionally-scaled "looks like 2560x1440" mode which gives the widely-preferred UI size (which actually looks pretty good, and a lot better than actual 1440p - but if you go hunting for artefacts or run GPU benchmarks you will find them).... but a 5k3k display gives you that sought-after UI size with no fractional scaling or artefacts. With 5k
2k - since the PPi is the same as a 4k of the same height - you're essentially in the same boat as with 4k
Don't get me wrong - 4k and 5k2k displays are perfectly valid options, as is using a large 4k display in native mode if you want lots of real estate, but there are good reasons why 4.5k, 5k3k and 6k are worth a premium on MacOS.
But that is what the definition [of 5k] is, that you don't agree with that is fine. Now please do show us a link to a ratified standard that only the way you measure it is the official definition?
I don't think there's an agreed, ratified standard for just "5k" either. From
Wikipedia:
This resolution is typically used in computer monitors to achieve a higher
pixel density, and is not a standard format in
digital television and
digital cinematography, which feature
4K resolutions and
8K resolutions.
[1]
Or,
this page from Wikipedia gives
UW5K or
WUHD for 5120x2160 and
UHD 5k for 5120x2880 - but there's no citations for those terms. Or, there's
this one that just gives 5k as 5120x2880. The
Dell display that started the fuss uses WUHD for 5120x2160 (which actually makes the most sense). OK Wikipedia isn't a good primary source, but if there was a clear, single,
official definition of 5k it would probably be cited - and the take-home message should be to
be specific rather than have arguments based on sketchy, hard-to-pin-down standards and marketing hyperbole.
Equally, we should really be saying "4k
UHD" when we mean 3840x2160 since there are
several standards for 4k (mostly with >4000 horizontal pixels) with various specific resolutions and aspect ratios. 4k UHD is an actual standard that specifically means 3840x2160. Problem is, I think, 5120x2880 should have gotten a VESA name like "QQHD" but didn't because it never really went PC mainstream.
So - as with many arguments about terminology - it's really about popular usage rather than standards. The term "4k" was popularised as usually meaning UHD by mass-market TVs and "5k" was popularised as usually meaning 5120x2800 by 5k iMacs 10 years ago - and wasn't ambiguous until very recently when 5k2k displays started appearing... but while a 5k2k WUHD display may be a perfectly good choice for a Mac it
does not meet the specific ppi criteria that makes -hah- 5k3k/QQHD (hah! it's called QQHD now because I say so
) particularly attractive to Mac users.
