Enable ClearType on Windows 10

I noticed jagged text on a computer running Windows 10.

It was particularly noticeable with Firefox and Chrome.

 

I opened Advanced display settings and tried to open ClearType text.

ClearType_01_Display_Settings

 

However this failed with this error message:

ClearType_02_Windows_cannot_access_cttune

C:\Windows\system32\cttune.exe

Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item.

 

Instead I tried to start cttune.exe directly:

ClearType_03_Run_cttune

 

This was possible and I noticed that ClearType was disabled (as expected).

ClearType_04_ClearType_disabled

 

I selected: Turn on ClearType

ClearType_05_ClearType_enabled

 

And completed the guide to adjust ClearType optimally.

ClearType_06_Adjusting_ClearType

 

That solved the problem. After enabling and adjusting ClearType, text in all programs looked much better without jagged edges.