Windows 10 dual monitor – lower res monitor is blurry

high-dpimultiple-monitorswindows 10

I have two monitors on my desktop computer running Windows 10.

1- Dell 2560 x 1440
2- HP 1920 x 1200

In "Customize your display", if I set both monitors at 100%, everything is sharp. If I set both at 125%, everything is still sharp. But if I set the Dell at 125% and the HP at 100%, the Dell is sharp but the HP is blurry.

I tried the registry fix that is suggested on many places on the internet (including SuperUser) but it's not working. As I understand it, this fix the issue when the monitor that is at 125% is blurry. But in my case, it's the one that is at 100% that is blurry.

The only other person I found that had the same issue resolved it by buying another high DPI display to have 2 monitors with the same resolution and scaling. Unfortunately, I don't have the budget for such a fix… 😉

Any idea on how I can fix this?

Best Answer

This is the way DPI scaling works on Windows 10. The primary display is used as a reference, so it’s always sharp. On other displays, there are two possibilities:

  • The application is “per-monitor” DPI aware – if correctly programmed, it will be sharp on all displays. It will use the DPI of the display where the majority of its window is located. Example: Firefox
  • The application is “system” DPI aware – it will be sharp on your primary display. On other displays with different DPI, it will not be sharp, because Windows will resample the output image. Example: MS Office

There are of course also unaware applications. Unfortunately, there aren’t many “per-monitor” aware applications. There are also applications that have the “per-monitor” aware flag, but do not scale at all. Lync/Skype for Business is one such application.

You can use Process Explorer to check program’s awareness (the column is deselected by default):

enter image description here

It might be noteworthy that DPI scaling on OS X works exactly the same, except it uses a less blurry scaling algorithm.

tl;dr: Working OK, by design.

Related Question