Sorry, this still isn't making sense to me. It sounds like you're trying to say that, if the listed resolution is twice the native screen resolution, then MacOS is doing supersampling. But I'm just guessing at what you're trying to say. It would be helpful if you could instead provide a link to a technical reference I could read on this.
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The subpixel-AA debacle and font rendering
- Thread starter mathcolo
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I recommend using a scaled resolution by the following trick:
https://comsysto.github.io/Display-...or-with-HiDPI-Support-For-Scaled-Resolutions/
Big Sur will probably automatically super-sample your screen (i.e. scale up 200% and then back down to 100%) which is nice. But if you are prepared to sacrifice a little space you can choose a nice mode in-between 2x scaling and 1x scaling which should made things sharper.
On a 1440p screen I have a 2048x1536 super-sampled mode which is sharper than 2560x1440 but has more space than a retina mode which would be 1280x720. This is effectively equivalent to Apple's "more space" option on a Macbook's internal screen, a type of compromise between retina and 1x scaling.
As far as I know there is very little information on this. Certainly Apple just expects you to use their ecosystem so they're not going to explain what to do with a Dell monitor.
There is a little info here:
https://www.anandtech.com/show/6023/the-nextgen-macbook-pro-with-retina-display-review/6
From what I figured out:
1) In HiDPI OS X always renders the desktop to a canvas which is double the resolution of your mode. The GPU then scales this down (or up) to the physical resolution of your monitor.
2) Before Big Sur this could be enabled manually, but now it seems to be the default.
3) Separate to the above, if you choose a resolution lower than your physical resolution each desktop element or font size is enlarged, and can therefore be represented by more pixels, so should be sharper. At a resolution half of your physical resolution (retina) it is sharpest as there is an exact pixel mapping.
4) If Apple had continued to use subpixel anti-aliasing then text would look fantastic using this approach. Unfortunately they don't so even the super-sampling trick doesn't beat a standard Linux or Windows desktop with subpixel AA. I suspect super-sampling + subpixel AA would provide too much of a performance hit, but that's only a guess. Obviously in the Apple ecosystem you don't need subpixel AA as you have a retina monitor!
This is exactly what I've been doing via https://github.com/avibrazil/RDM , but I just purchased a 38" Ultrawide and don't want to be shooting myself in the foot if Big Sur breaks the ability to make these changes. It would be unfortunate to find out the display is worse in a few months due to a technical change.
I've seen reports that Big Sur will give super-sampling at 100% (and probably 200%) scaling on non-Apple monitors. However if you want the kind of in-between custom scaling ("more space") that I described I'm not sure. I would hope it still works.
I went ahead and installed Big Sur on a spare external and I can confirm as of Beta 2 they use HiDPI mode without any tweaks to the OS. It actually looks pretty darn good. Now I have to decide if I’m going to keep this ultrawide or stick to my 3x 4K displays scaled down.
Do you think the text rendering looks any better than Catalina? I was thinking that on that alone it would look the same. But there is also some mention of something called Optical Sizing which is supposed to improve how fonts are rendered at different sizes.
I'm not sure if its a placebo effect, but I'd lean more towards it being an improvement compared to Catalina. This might have to do with how the OS is just laid out differently.
There are some areas that aren't rendering nicely (see attached - specifically the spotlight icons) and I assume this is because it's still in beta. I think I'll be sticking to my 4K displays because the over smoothing on both operating systems begins to give me a headache after a while.
Attachments
It's kind of puzzling that they do this heavy smoothing, basically making the fonts look bold everywhere. When I tried Apple's San Francisco Font under Linux it looks great with sub-pixel AA. Just the right amount of smoothing. Not too spidery like Windows, and not too "fat" like OS X.
I originally come from a design background so maybe I’m being overly critical because I know what to look for. It doesn’t look terrible and at a greater distance you might not even tell the difference.
I typically worked at a scaled resolution of 3008x1692 on my 27” so the PPI (if I’m calculating correctly) is an unsubstantial difference of 18.35 on my 38” ultrawide.
@theorist9
this is a quote i found from a different forum:
ex-MacOS SWE here. Subpixel antialiasing is obnoxious to implement. It requires threading physical pixel geometry up through multiple graphics layers, geometry which is screen-dependent (think multi-monitor). It multiplies your glyph caches: glyph * subpixel offset. It requires knowing your foreground and background colors at render time, which is an unnatural requirement when you want to do GPU-accelerated compositing. There's tons of ways to fall off of the subpixel antialiased quality path, and there's weird graphical artifacts when switching from static to animated text, or the other way. What a pain!
Nevertheless there's no denying that subpixel-AA text looks better on 1x displays. Everyone notices when it's not working, and macOS will look worse without it (on 1x displays).
this is a quote i found from a different forum:
ex-MacOS SWE here. Subpixel antialiasing is obnoxious to implement. It requires threading physical pixel geometry up through multiple graphics layers, geometry which is screen-dependent (think multi-monitor). It multiplies your glyph caches: glyph * subpixel offset. It requires knowing your foreground and background colors at render time, which is an unnatural requirement when you want to do GPU-accelerated compositing. There's tons of ways to fall off of the subpixel antialiased quality path, and there's weird graphical artifacts when switching from static to animated text, or the other way. What a pain!
Nevertheless there's no denying that subpixel-AA text looks better on 1x displays. Everyone notices when it's not working, and macOS will look worse without it (on 1x displays).
Yeah, I've seen that. I don't know if the details are technically accurate or not, but it probably did make things simpler for Apple to drop subpixel AA, since why eliminate it otherwise? Having said that, even if it is a hard thing to do, they certainly were fully capable of implementing it well, so this post doesn't explain why keeping something that they knew how to do well would be a problem. After all, I'm sure there are lots of graphics features in MacOS that are challenging to implement, yet Apple keeps them because they make the OS look good.
There's also this old trick which still works on Catalina, maybe also on Big Sur?. Might try light font smoothing later
https://colinstodd.com/posts/tech/fix-macos-catalina-fonts-after-upgrade.html
I always hesitate to post screenshots of font rendering as you really need to be in front of the screen to see the true effect, however I think these pictures are informative.
The following is text rendered in Microsoft Office/Libre Office on Windows, then Linux, then OS X using the Arial Font. You can see the Microsoft are using grayscale AA, Linux uses RGB subpixel AA, and OS X uses grayscale AA + x2 supersampling.
In real life the outcome is that on Windows the text is sharp but spidery often with distortion of letterforms (look at the stem on the f of fox, or the difference between the two legs of the n of brown). OS X appears to recreate the font in a heavy bold format where nothing is distorted but little attempt is made to represent the letters efficiently with fewer pixels. Linux renders text very pleasantly, in a nice readable manner on a non-retina monitor. (Unfortunately the sub-pixel effect doesn't come across well in a screengrab, so the 2nd screenshot isn't ideal)
Sadly, OS X is just too bold everywhere for my liking. The logic seems to be just to make all the letters fatter at small sizes which does represent each letter with more pixels but is fatiguing to read.
The following is text rendered in Microsoft Office/Libre Office on Windows, then Linux, then OS X using the Arial Font. You can see the Microsoft are using grayscale AA, Linux uses RGB subpixel AA, and OS X uses grayscale AA + x2 supersampling.
In real life the outcome is that on Windows the text is sharp but spidery often with distortion of letterforms (look at the stem on the f of fox, or the difference between the two legs of the n of brown). OS X appears to recreate the font in a heavy bold format where nothing is distorted but little attempt is made to represent the letters efficiently with fewer pixels. Linux renders text very pleasantly, in a nice readable manner on a non-retina monitor. (Unfortunately the sub-pixel effect doesn't come across well in a screengrab, so the 2nd screenshot isn't ideal)
Sadly, OS X is just too bold everywhere for my liking. The logic seems to be just to make all the letters fatter at small sizes which does represent each letter with more pixels but is fatiguing to read.
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Sadly I don't think that Apple is worried about the non-hidpi users anymore and plan to continue forward in focusing on font rendering. I really like my ultrawide, but I think I'll be sticking with my 4K displays.
I would love to go 4k or 5k but my rule is that the monitor mustn't be larger than 25 inch, 24 inch ideally. Personally I just don't like the larger sizes. and it mustn't be a stupidly high price.
There's only one hidpi monitor that fits that, a 2014 4k Dell model, and it has poor reviews.
I'm currently running a 24 inch 1440p model from Dell (2020) and it is very good under Linux, and bearable with OS X.
There's only one hidpi monitor that fits that, a 2014 4k Dell model, and it has poor reviews.
I'm currently running a 24 inch 1440p model from Dell (2020) and it is very good under Linux, and bearable with OS X.
The discontinued LG panel (4096x2304 in 22") was wonderfully suited for Macs.
Shame it's gone (and that it wasn't used in more monitor products when it was around).
Shame it's gone (and that it wasn't used in more monitor products when it was around).
What versions of Windows, MacOS, annd Linux were were you using?
With the 2x supersampling on MacOS, were the letters the same actual size as those from Windows and Linix on your display? Because from your screenshots it looks like they were displayed with twice as many screen pixels, which means they would take up twice the screen real estate.
Also, could you add a fourth to your comparison: High Sierra?
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Windows 10, Catalina, KDE with cleartype patch (as cleartype is out of copyright now)
Actually this is the conundrum. It is impossible to screenshot what I actually see, as the OS X screen grab app always returns the framebuffer which is, of course, double the pixel dimensions. I don't have access to the result of the final GPU downscaling.
I don't have High Sierra, but would be interesting if someone else could do this. You just need to take a screenshot of text and zoom in say 600%.
This is what it looks like in High Sierra, Arial in MS Word.
If I understand correctly what you've done, what you're showing isn't (no pun intended) an apples-to-apples comparison. From what I see, you're using twice as many native pixels in displaying the Catalina result as the Windows or Linux results. This unfairly favors the Catalina result by a factor of two. I.e., it makes Catalina look twice as sharp, by comparison to the other two, as it actually is.
You are correct but the apples-to-apples comparison is impossible as i don't think you can take a screengrab of the screen *after* the GPU has downscaled the framebuffer. In fact, from what I understand all programs that run in OS X think they are rendering on the doubled size canvas. The GPU alone is doing the final downscale right at the end of the rendering pipeline for each frame sent to the screen.
I could do a software bicubic downscale in photoshop to reduce the number of pixels for the comparison, but I don't actually know if the GPU does that, or if it is more sophisticated.
Probably taking a photo of the screen would be the only way to compare!
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Yes, taking a photo is how I've done it. Though an alternative might be to reduce the font size in Catalina by half, so that the measured sizes with which all your phrases display on their respective OS's is the same (i.e., take a short plastic ruler, lay it flat on your display, and ensure the phrase measures out to the same length when displayed in all three OS's).
so I turned down the font smoothing from heavy (3) to light (1) which improved sharpness a bit.
(Check yours with "defaults read -globalDomain AppleFontSmoothing" in terminal)
this is a smaller point size with light smoothing zoomed in on Catalina. Not surprisingly it looks similar to Windows grayscale AA but better executed in my opinion. Every letter is treated evenly, e.g. compare the letter i between the two. The weird butchering of the inverted commas I think is some straight quote replacement feature of MS Word.
On a side-note I've actually noticed that certain modern web/cross platform apps such as Evernote and Teams, which implement their own version of grayscale AA, and their own purpose-designed fonts, do very well on sharpness. Not as good as subpixel, but a decent effort.
This is, I guess, the other approach. Design a font from scratch, designed for the screen, that scales well and fits into a small number of pixels whilst remaining legible. Apple have done some work here with their San Francisco font which comes in Display and text versions, optimised for large and small sizes respectively. Perhaps Big Sur improves on this with its optical sizing technology. Not managed to find much information on that so far...
(Check yours with "defaults read -globalDomain AppleFontSmoothing" in terminal)
this is a smaller point size with light smoothing zoomed in on Catalina. Not surprisingly it looks similar to Windows grayscale AA but better executed in my opinion. Every letter is treated evenly, e.g. compare the letter i between the two. The weird butchering of the inverted commas I think is some straight quote replacement feature of MS Word.
On a side-note I've actually noticed that certain modern web/cross platform apps such as Evernote and Teams, which implement their own version of grayscale AA, and their own purpose-designed fonts, do very well on sharpness. Not as good as subpixel, but a decent effort.
This is, I guess, the other approach. Design a font from scratch, designed for the screen, that scales well and fits into a small number of pixels whilst remaining legible. Apple have done some work here with their San Francisco font which comes in Display and text versions, optimised for large and small sizes respectively. Perhaps Big Sur improves on this with its optical sizing technology. Not managed to find much information on that so far...
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