Glad they are working on this issue.

My monitors:

• Main monitor: P2715Q, 27", 3840x2160, landscape mode, DPI 200%;
• Secondary monitor: P2415Q, 24", 3840x2160, portrait mode, DPI 225%;

I prefer to put Mathematica notebooks on my secondary monitor as it is in portrait mode, perfect for Mathematica notebooks.

I wish Wolfram engineers make Mathematica a true DPI aware software, UI should not be blurry no matter the DPI settings of each monitors.

Many DPI aware software on Windows 10 display correctly on main monitor, but UI looks blurry on secondary monitors (if DPI settings of main monitor and secondary monitors are different).

For example:

• Many (if not most) Microsoft's own software (including Windows Explorer, Microsoft Office 2016, Visual Studio 2017, Process Explorer...).
• JetBrains Rider;
• JetBrains WebStorm;
• SmartGit;

There are other software works perfectly no matter what DPI you use on main monitor and secondary monitors.

For example:

• Google Chrome
• Firefox
• Windows Store apps (e.g. Microsoft Edge, Todoist...)
• Visual Studio Code (based on Electron, they fixed this issue recently)
• Neo4j Desktop
• PotPlayer

I have the same problem with my 4K monitor (Windows 10, newest version).

Also I am running mathematica 11.2 on my MacBook Pro (2012, Retina display, macOS Sierra 10.12.6), and there the OS has no problems, everything is perfect as it should be.

See this questions:

Stackexchange:

• https://mathematica.stackexchange.com/questions/134054/blurry-fonts-in-notebooks

• https://mathematica.stackexchange.com/questions/123717/mathematica-11-with-high-dpi-4k-screen

Comments:

Microsoft:

https://blogs.windows.com/buildingapps/2017/04/04/high-dpi-scaling-improvements-desktop-applications-windows-10-creators-update/

Others:

• https://www.digitaltrends.com/computing/how-to-adjust-high-dpi-scaling-in-windows-10/

• https://www.howtogeek.com/175664/how-to-make-the-windows-desktop-work-well-on-high-dpi-displays-and-fix-blurry-fonts/

I warned people. :)

Apple worked on HiDPI interfaces for years, I worked in the Core Graphics group while I was at Apple... it's not an easy challenge. You can take the naive approach and scale lower resolution content but thats really not enough because you end up with all the problems described. With LCD monitors you have to take into account a lot of edge information for RGB components of the LCD panel, layouts of glyphs and additional font information. Apple HiDPI actually works at a sub-pixel level to correct font placement for true type, which makes it look more accurate.

A typical 4k monitor display can actually display at 16k for 4x sampling, I know my Dell 4K monitor will display a 16k resolution but thats typically reserved for hardware oversampling a 4k resolution which just doesn't work for all situations well.

With 30 years in computer graphics my eye picks up all the errors and it just annoys me to no end to see these scaling issues, so I would rather live with a pixel accurate display than one that isn't.

To do it right the application has to render at the target resolution and not rely on naive scaling implementations between them and the user.

But does Mathematica look blurry on your primary (boot) monitor or you found a way to make it work at least within one High DPI monitor?

As you mentioned, most applications look great at 200% within main monitor. Say, for me Microsoft Office, SmartGit look perfectly sharp. Not Mathematica, not even in primary monitor (see screenshot in my first post).

(The forum scales my screenshots, makes them look more blurry, try copying them to your local machine and zoom in 100%)

@Luis Rademacher, I noticed you used 150% DPI on your 4K monitor. You may not want to do that as it will make non DPI aware software look more blurry.

I'm not a computer or math expert, so I could be wrong, but I think for those non DPI aware software, when you set DPI to 100%, 200%, 300%, etc, to scale their UI, operating system only needs to clone original pixels. But when you set DPI somewhere between 100%, 200%, 300%..., OS needs to do some calculates and create fake pixels, makes UI look more blurry. I have tested this many times for non DPI aware programs.

Screenshots below are from my Dell P2715Q, 3840x2160, "DPI scaling behavior" and "Magnification" are default values.

Under 150% DPI:

Under 200% DPI:

As you can see, under 150% DPI, UI is painfully blurry, but under 200% DPI, you can see the pixels, but it's kind of usable.

Same is true for other non DPI aware software, for example: Fusion 360.

That's why I always keep my main 4K monitor 200% DPI.

I agree that integer multiples of 100% work better for the reasons you mention. Unfortunately 150 is quite far from 100 and 200, so not really an option to jump to the nearest value (I have a 28" monitor that looks great at 150%, at 200% would be quite wasteful of space).

I tried that. I doesn't fix the issue for me. At 100% every app and interface element in Windows looks unreadably tiny. A 4k monitor typically has about 4 times as many pixels as a 1920 and therefore a scaling like 150% is more or less necessary. At that scaling almost every programs in Windows looks great, with sharp fonts and good size, except Mathematica.

If I use MM scaling as suggested (with Windows scaling at 100%), everything else in Windows is still tiny and many elements of Mathematica's interface (e.g. menu bar) are still tiny.

It does not solved in version 11.3. It is disappointing.

No one will like this solution... I had a Dell 4k monitor and this affected too many applications on Windows 10, by chance I kept my Eizo 27" display with a native 2560 × 1440 resolution.. after a year I went back to the Eizo.

Problem solved.

I can say my 27" iMac with a 5k display does a much better job across the board for all applications.

The Dell 4K is on craigslist at a deep discount :)