External display 27"/4k - Scaling problem, really?

[migoelo]

Hi all,

Has anything changed with Ventura when scaling the UI? I've stayed away from a Macbook for years because of the constant talk of reduced screen sharpness on external displays when using a 27"/4K monitor, for example. Now I'm a new owner of a MacBook Air 15", and I'm using a DELL U2720Q 27"/4K monitor with the scaling 3008x1692. I chose this scaling because it's the only way to make the font size appear similar on both displays, if I leave the Macbook scaling to standard, which I prefer. The pixel density is a bit lower on the DELL, but a visual difference is not really noticeable for me when working. Thus, I cannot quite understand the negative rating of such a combination. What is your opinion?

Best
Michael

 

[motrek]

Has anything changed with Ventura when scaling the UI? I've stayed away from a Macbook for years because of the constant talk of reduced screen sharpness on external displays when using a 27"/4K monitor, for example. Now I'm a new owner of a MacBook Air 15", and I'm using a DELL U2720Q 27"/4K monitor with the scaling 3008x1692. I chose this scaling because it's the only way to make the font size appear similar on both displays, if I leave the Macbook scaling to standard, which I prefer. The pixel density is a bit lower on the DELL, but a visual difference is not really noticeable for me when working. Thus, I cannot quite understand the negative rating of such a combination. What is your opinion?

The "problem" is that the OS renders everything internally at 6016x3384 (double your virtual resolution of 3008x1692) and then scales it down to be displayed at the physical resolution of 3840x2160.

The internal rendering resolution isn't infinite, so images are scaled and text is antialiased to suit that resolution. Then everything is scaled down again to the physical resolution. So you're essentially looking at a xerox of a xerox of an image that only exists as a concept. So everything is a bit "softer" than it would be, ideally.

(It's worth mentioning that if anything lined up on pixel boundaries at the internal resolution, it won't line up on pixel boundaries at the physical resolution, and will thus also look "softer.")

That all being said, if you have a 27" monitor with 4K resolution, that is retina resolution from a distance of 21 inches or more. (Retina resolution meaning 60 pixels per visual degree.)

So if you're sitting at least 21 inches away from your monitor, it will be basically impossible for you to notice any of this softness/blurriness.

Personally I have a 27" 4K monitor and I run it at a virtual resolution of 2560x1440 and I think it looks fine. From a distance, it's indistinguishable from 5K. If I move my head closer, I can tell the difference, the image does look softer, but it's not bad.

 

[kvic]

The "issues" of 4K monitors with Macs are blown out of proportion by miles and miles!

Received my 4K display over the weekend. Have been testing, pixel sniffing and what not for many hours. The performance exceeds my expectation by a lot, I meant a lot. The '1440p scaled resolution' in MacOS looks great. Compared to the visual experience of native scaling in Windows 11, I would say the MacOS's primitive scaling method surprisingly gives a much better visual experience.

I believe the "4K issues" among most Mac users (who complain) boil down to: when they spot difference in side by side comparison, any difference by non Apple vendors is an issue of the 3rd party vendor, any difference by Apple is a merit from Apple. lol

I should also mention I never used two monitors with different models, brands side by side. Will never do. When side by side, all must be the same make.

 

[motrek]

The "issues" of 4K monitors with Macs are blown out of proportion by miles and miles!
...

Yeah. There are a ton of videos on YouTube and articles on the web about how MacOS scaling is super bad because nothing lines up on pixel boundaries, but:

1) Not much that's displayed by MacOS lines up on pixel boundaries anyway. Text doesn't, nor does anything in basically any image you might be looking at. I suppose borders for various UI elements (window frames, button edges, etc.) often line up on pixel boundaries, but that's about it.

2) At 163 PPI and normal viewing distances for a desktop monitor, you'd basically need superhuman vision to tell if something is lined up exactly on a pixel boundary, or if it's antialiased a bit.

A lot of people complain about how crappy scaled resolutions look, but I'd like to see if those people could pass a double-blind experiment to see if they could actually tell a difference between a 4K monitor and a 5K monitor from 21 inches away.

 

[kvic]

A lot of people complain about how crappy scaled resolutions look, but I'd like to see if those people could pass a double-blind experiment to see if they could actually tell a difference between a 4K monitor and a 5K monitor from 21 inches away.

I'm sure they won't be able to tell a difference at normal viewing distance.

I would even go further and say that those with superhuman vision and able to spot a difference would actually want font anti aliasing back in MacOS on a 5K display. This old technology was created to exactly counter ppl able to perceive individual pixels on old non-HiDPI monitor viewed at normal distance.

Superhuman vision would need better than 5K on a 27-inch. I'm not sure that's a blessing. They seem to have little idea what they're whining.

 

[motrek]

...
I would even go further and say that those with superhuman vision and able to spot a difference would actually want font anti aliasing back in MacOS on a 5K display. This old technology was created to exactly counter ppl able to perceive individual pixels on old non-HiDPI monitor viewed at normal distance.
...

To be clear, MacOS still does text antialiasing, with grey pixels.

What Apple gave up on was subpixel antialiasing. That's when the OS deliberately puts colored fringing on the edges of text in order to darken the colored sub-pixels closest to the text. (For example, if you set a pixel to yellow instead of white, that darkens the blue sub-pixel. Yellow is red + green.) That basically increases the horizontal resolution of the monitor by 3x, at the expense of color accuracy.

Subpixel antialiasing was an amusing idea, but completely useless when an entire pixel is so small that nobody can really make it out anyway.

 

[rumz]

I don’t have superhuman vision.

I use a 4k 27” monitor at the office next to a the 21.5” 4k display.

In general use the 27” is fine, but my non-superhuman vision can discern the difference between the 2. The 4k 27” looks soft enough that I prefer to primarily use the 21.5” 4k. To be fair, there’s a chance I wouldn’t have a gripe if I didn’t have that higher dpi monitor next to it. (At home I still use a 109ppi ultra wide to do the same work and it’s adequate for my non-superhuman vision even without subpixel antialiasing).

But there have also been instances where things like 1 pixel lines appear a bit blurred on the 27” 4k display (where they do not look blurred at the same scale on the 21.5“ 4k)— that alone is enough that I would never consider purchasing one for myself for my design work as long as I’m using Mac.

So, as with so many things… YMMV. Depending on what you use the display for and the level to which it matters to you.

 

[kvic]

What Apple gave up on was subpixel antialiasing.

Oh, you're right. subpixel antialiasing is more precise term for what I had in mind.

I use a 4k 27” monitor at the office next to a the 21.5” 4k display.

In general use the 27” is fine, but my non-superhuman vision can discern the difference between the 2

Quoting myself from a previous reply above, "I should also mention I never used two monitors with different models, brands side by side. Will never do. When side by side, all must be the same make."

Always get the same model if you use multiple monitors side by side.

 

[motrek]

I don’t have superhuman vision.

I use a 4k 27” monitor at the office next to a the 21.5” 4k display.

In general use the 27” is fine, but my non-superhuman vision can discern the difference between the 2. The 4k 27” looks soft enough that I prefer to primarily use the 21.5” 4k. To be fair, there’s a chance I wouldn’t have a gripe if I didn’t have that higher dpi monitor next to it. (At home I still use a 109ppi ultra wide to do the same work and it’s adequate for my non-superhuman vision even without subpixel antialiasing).

But there have also been instances where things like 1 pixel lines appear a bit blurred on the 27” 4k display (where they do not look blurred at the same scale on the 21.5“ 4k)— that alone is enough that I would never consider purchasing one for myself for my design work as long as I’m using Mac.

So, as with so many things… YMMV. Depending on what you use the display for and the level to which it matters to you.

As I posted above, 27" 4K is retina resolution from 21 inches away.

I can very easily tell the difference between 4K and 5K from closer distances. I assume most people can.

I think a lot of people have convinced themselves that they can see a difference from further distances (and they complain about it bitterly) because of things they've read or seen on the internet, but if push came to shove and they were in a controlled experimental environment, they wouldn't be able to tell.

 

[motrek]

I was inspired by a different thread to compare scaled vs. not-scaled resolutions by taking RAW photos of each.

On the left is 12-point text rendered at not-scaled resolution (i.e., "integer scaling") on my monitor. On the right is 16-point text rendered at a scaled resolution that makes it the same physical size as the 12-point text at the left.

In other words, the text on the left-hand side is being rendered at native physical resolution and the text on the right-hand side is being rendered at a higher virtual resolution and then scaled down.

Many people have claimed that, when running at a scaled resolution, text rendering is such a disaster (due to scaling artifacts) that they consider scaled resolutions unusable.

Personally, I'm hard-pressed to tell any difference at all, even when I'm essentially looking at the monitor with a magnifying glass...

 

[Schnegg]

What do you guys think about 4K resolution on a 32" screen, is it too rough with the scaling? I currently use a 4K 27" screen both on Mac and Windows and could use some extra real estate.

 

[DennisdeWit]

What do you guys think about 4K resolution on a 32" screen, is it too rough with the scaling? I currently use a 4K 27" screen both on Mac and Windows and could use some extra real estate.

I did this with the AOC U32U1. It’s really not bad, but still I prefer the much sharper text from the Pro Display XDR I have now. And yes, I can see the difference between font sharpness. My eyes get less tired.

 

[edubfromktown]

I use (LG) 21.5 and (AOC) 27" 4k displays with my Studio and dual 27k's with this same 27" and 2nd Dell 27" 4k on Windows (work) laptop in my home office.

Doesn't bother me having mixed manufacturer displays though Windows font rendering does bother me

For a least common denominator setup across two OS platforms that I use on a daily basis, it is not bad.

If I had my choice I would go Pro Display XDR on the Mac though if I did, everything else would look like crap.

 

[motrek]

What do you guys think about 4K resolution on a 32" screen, is it too rough with the scaling? I currently use a 4K 27" screen both on Mac and Windows and could use some extra real estate.

Probably a good way to get an idea of sharpness is to divide physical pixels by logical pixels.

A "normal" (non-retina, not HiDPI) Apple display had 1 physical pixel per logical pixel. Not that Apple sells any of these anymore.

An Apple "retina" display will have 4 physical pixels per logical pixels by default ("pixel-doubled" on both axes).

A 4K display (3840x2160) running a logical resolution of 2560x1440 has 2.25 physical pixels per logical pixel. So it has sharpness kinda halfway in-between retina and non-retina. A little bit closer to retina.

If you run a virtual resolution of 3008x1692 to get some extra screen real estate, you're getting down to 1.62 physical pixels per logical pixel. That's getting pretty close to just running at normal not-HiDPI resolution, which is pretty rough.

It would be really nice if somebody bothered to make a 32" 5K display...

 

[kvic]

What do you guys think about 4K resolution on a 32" screen, is it too rough with the scaling? I currently use a 4K 27" screen both on Mac and Windows and could use some extra real estate.

When the native resolution is fixed, 4K in this case, a bigger screen size will not give you more *screen real estate*. It gives you more *viewing distance*. That's if people want to sit a bit farther away from their display, for whatever reason.

Some people may claim that they could run a 32-inch 4K display at a higher scaled resolution in MacOS e.g. at "look like 3008x1692" instead of "look like 2560x1440" and get more screen real estate and a better experience. I.e a mystical combination of "look like 3008x1692" + 32-inch + an increased viewing distance appears better to them on a 32-inch 4K than a 27-inch 4K at "look like 3008x1692". I very much doubt it and don't believe a bit of such people's saying. Nevertheless you could try it out yourself.

I think 27-inch 4K turns out pretty good. Perhaps that's the reason behind its popularity. Its optimal viewing distance is around 55-60cm in front of the screen, which is where people usually work. I believe 27-inch 5K will never have a chance to come back and win given the 'outrageous' price point compared to a 4K.

So perhaps the war is done at 27-inch. At 32-inch, it's still to be decided.

 

[motrek]

When the native resolution is fixed, 4K in this case, a bigger screen size will not give you more *screen real estate*. It gives you more *viewing distance*. That's if people want to sit a bit farther away from their display, for whatever reason.

Some people may claim that they could run a 32-inch 4K display at a higher scaled resolution in MacOS e.g. at "look like 3008x1692" instead of "look like 2560x1440" and get more screen real estate and a better experience. I.e a mystical combination of "look like 3008x1692" + 32-inch + an increased viewing distance appears better to them on a 32-inch 4K than a 27-inch 4K at "look like 3008x1692". I very much doubt it and don't believe a bit of such people's saying. Nevertheless you could try it out yourself.

I think 27-inch 4K turns out pretty good. Perhaps that's the reason behind its popularity. Its optimal viewing distance is around 55-60cm in front of the screen, which is where people usually work. I believe 27-inch 5K will never have a chance to come back and win given the 'outrageous' price point compared to a 4K.

So perhaps the war is done at 27-inch. At 32-inch, it's still to be decided.

Back when I had a 24" monitor (and smaller), I thought it was normal to only look at it from viewing distances such that I could see the entire image at the same time, i.e., without moving my head around.

When I got a 27" 1440p monitor, the monitor was so big and the text/UI was so small that I had to get used to the idea of looking at it from a closer distance and being comfortable with the idea that I wouldn't necessarily be able to see the entire image at once. It was awkward for a week or two but I got used to it.

I think 32" gives you the option of either sitting far away and having everything be very comfortable to read, or sitting close-up and having a lot of available real estate.

But 4K isn't a super-awesome resolution for a monitor that big...

 

[kvic]

Back when I had a 24" monitor (and smaller), I thought it was normal to only look at it from viewing distances such that I could see the entire image at the same time, i.e., without moving my head around.

When I got a 27" 1440p monitor, the monitor was so big and the text/UI was so small that I had to get used to the idea of looking at it from a closer distance and being comfortable with the idea that I wouldn't necessarily be able to see the entire image at once. It was awkward for a week or two but I got used to it.

I think 32" gives you the option of either sitting far away and having everything be very comfortable to read, or sitting close-up and having a lot of available real estate.

But 4K isn't a super-awesome resolution for a monitor that big...

For me, the idea of viewing distance was carried over from older days of TVs to computer displays. So called "videophiles" will preach this and that. Viewing distance turns out actually quite scientific. Btw, entering digital age, TV and computer displays basically converged. With Apple's heavy marketing effort on "Retina" display, the idea of viewing distance seemed to become more prevalent in computer users.

But judging from user posts on MR, I believe a significant portion of users still unaware of viewing distance for a given display. Or put it the other way, given their fixed viewing distance, how to pick a right monitor of combined resolution and screen inch. Also, worth emphasising, computer users usually can't change their viewing distance. A typical office/home desk is of similar depth. Your hands have to comfortably reach keyboard and mouse. All these limit the adjustability of their viewing distance.

I really think 27-inch is very nice form-factor for a typical desk. And 27-inch 4K (in "look like 1440p" scaled mode in MacOS or 150% scaled mode in Windows) is a pretty good solution as computer display. If people want more screen real estate, multi-monitor setup is the way to go due to economy and ergonometric IMO. With two displays, one at 0 degree (in from of you), the other at 45 degree (on the right or left of you). With three displays, all in landscape mode is one option, one at 0 degree, the other two at 30 degree on either sides. Your head only has to swivel a little combined with eye balls movements.

32-inch (at a suitable resolution, say 6K) will be a better alternative to gain more screen real-estate if you only want ONE single display on a typical desk. I have some doubt in multi-monitor setup in the common portrait mode but I've to admit I never experience it.

 

[Schnegg]

Thank you all for your inputs. One of my issues with 5K displays and up is actually that my Windows laptop from work has a hard time handling them. I guess I'll keep the 27" with 1440p scaling going for a while, even though I think 24" would actually be the right size for 4K.

I'm gonna keep an eye on the monitor market. Productivity gain on large screens is real for me, I sometimes use a Samsung 34" curved thing (non-retina) in another location and it really is nicer than separate screens.

And as mentioned the damned Windows font rendering cannot be helped at any resolution...

 

[Basic75]

What do you guys think about 4K resolution on a 32" screen, is it too rough with the scaling? I currently use a 4K 27" screen both on Mac and Windows and could use some extra real estate.

If you've followed the discussion this far you'll have seen that "too rough" is very subjective and we can't answer that question for you.

 

[cinedog]

Can someone confirm that scaling only affects UI and not video? For example, if I have a 4k monitor but I play a full screen 4k Youtube video, then that should display as full 4k on my 4k monitor, regardless of what scale ("Looks like 1080p") I set it at?

 

[StuAff]

Can someone confirm that scaling only affects UI and not video? For example, if I have a 4k monitor but I play a full screen 4k Youtube video, then that should display as full 4k on my 4k monitor, regardless of what scale ("Looks like 1080p") I set it at?

Yes. Ditto with desktop wallpaper, etc. It's only the UI that gets scaled.

 

[arw]

Can someone confirm that scaling only affects UI and not video? For example, if I have a 4k monitor but I play a full screen 4k Youtube video, then that should display as full 4k on my 4k monitor, regardless of what scale ("Looks like 1080p") I set it at?

Video is affected in the same way the rest of the UI is.
In your case it just doesn't make any difference:

It only matters if you use a scaled resolution with a non integer scale value.
As others have pointed out, "Looks like 1080p" is the exact 2x retina resolution for a 4K display with a resolution of 3840x2160.
The display's physical resolution matches the framebuffer resolution (the resolution at which macOS is rendered internally).
So all good for a 4K video as in this case, each video pixel gets mapped exactly to one display pixel.

But if you select a.e. "Looks like 2560x1440" (1440p) the whole UI gets rendered in 5120x2880 (framebuffer) - including a full screen video. Then it gets truncated down to 3840x2160 again to match the display's physical 4K resolution.

While technically the 4K video first gets upscaled and then downscaled again, the visual differences are almost impossible to perceive (that's why I put 'matters' in italics).

But compare the fabric in the attached photo (4K video, 4K display):
- In the 1st photo (looks like 1080p, framebuffer 3840x2160) one video pixel is directly mapped to one display pixel
- The 2nd photo (looks like 1440p, framebuffer 5120x2880) shows that the up- and downscaling process results in lost details and smoother edges (although minimal).

(Video players like IINA have an option "use physical resolution for retina displays".
But this still uses the framebuffer resolution, not the actual physical resolution of the panel.)

EDIT: In regard to video consumption I concur to classify any concerns as 'pixel sniffing'. I just wanted to answer @cinedog's question thoroughly.
However, I still avoid fractional resolutions for photo editing as I am incapable of properly assessing the sharpness in Photoshop which only renders in native or 2x resolution. But that's a completely different use case and reasoning.

 

[cinedog]

Video is affected in the same way the rest of the UI is.
In your case it just doesn't make any difference:

It only matters if you use a scaled resolution with a non integer scale value.
As others have pointed out, "Looks like 1080p" is the exact 2x retina resolution for a 4K display with a resolution of 3840x2160.
The display's physical resolution matches the framebuffer resolution (the resolution at which macOS is rendered internally).
So all good for a 4K video as in this case, each video pixel gets mapped exactly to one display pixel.

But if you select a.e. "Looks like 2560x1440" (1440p) the whole UI gets rendered in 5120x2880 (framebuffer) - including a full screen video. Then it gets truncated down to 3840x2160 again to match the displays physical 4K resolution.

While technically the 4K video first gets upscaled and then downscaled again, the visual differences are almost impossible to perceive (thats why I put 'matters' in italics).

But compare the fabric in the attached photo (4K video, 4K display):
- In the 1st photo (looks like 1080p, framebuffer 3840x2160) one video pixel is directly mapped to one display pixel
- The 2nd photo (looks like 1440p, framebuffer 5120x2880) shows that the up- and downscaling process results in lost details and smoother edges (although minimal).

(Video players like IINA have an option "use physical resolution for retina displays".
But this still uses the framebuffer resolution, not the actual physical resolution of the panel.)

Fascinating! So in the case of a 4k 27in monitor using "Looks like 2560x1440", it's still doing the scaling up and down in the background even though the video source can perfectly fit the physical resolution (4k YouTube video on a 4k monitor).

Initially, I had thought somehow the full screen video could override this. Let me run a quick setup example by you. I'm a video editor and was planning on getting a triple monitor setup. My original plan was to buy triple 5k 27in monitors (Studio Displays or the new Samsung S9). All of these monitors would be set to "Looks like 2560x1440" because I want that clean 2x scaling instead of fractional scaling. But one of these monitors will be a clean feed view, meaning in DaVinci Resolve this monitor would be showing the timeline's video output full screen (it'll only ever be used to show videos full screen). This got me thinking if I should replace that monitor with a 4k monitor instead, since I had assumed that videos were unaffected by scaling.

Based on what you said, it wouldn't make a real difference if I buy the 4k monitor or not for the dedicated clean feed monitor, because the 4k video will be scaled regardless to 5120x2880 in the frame buffer, and then re-interpreted back to the 4k display, so I might as well just stick with 3 5k displays. Does that sound right? Also, doesn't you answer completely contradict @StuAff's?

 

[kvic]

What described by @arw is a good account of what's happening for fractional scaling in Apple MacOS (and some other platforms too). Lots of people here did not get it right, especially those Apple fanboys.

However, his explanation may be fuelling Apple fanboys who claim their "5K is superb and crystal sharp, and their 4K experience is horrible and blurry to hell". Hence, I'm rising from my grave to give a picture of what's happening for the 5K.

So that's right. 4K full-screen video on 4K display in fractional scaled resolution will be upscaled and then downscaled as @arw described. But that's probably the only (I meant only) situation that you lose pixel perfectness that you would otherwise get in an integeral scaled resolution.

Apple for Apple. In this scenario what will happen to the 4K video in full screen mode on a 5K display? You guess it right. The 4K video will be upscaled to 5K (the physical resolution of the display). Hence, it's not pixel perfect either.

For a 5K display, there is only one (I mean only one situation) that a 4K video is pixel perfect. That is it's played back in a 3840x2160 window.

In all other scenarios, regardless 4K display or 5K display, 4K video playback is never pixel perfect.

 

[Basic75]

Based on what you said, it wouldn't make a real difference if I buy the 4k monitor or not for the dedicated clean feed monitor, because the 4k video will be scaled regardless to 5120x2880 in the frame buffer, and then re-interpreted back to the 4k display, so I might as well just stick with 3 5k displays. Does that sound right?

If you buy a 4K monitor you don't have to run it with a 5120x2880 framebuffer!

If you choose native 3840x2160 resolution or "looks like 1920x1080" you'll have a 3840x2160 framebuffer and of course get a pixel-perfect 1:1 rendering of a 3840x2160 video in full-screen.