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With the general widespread deployment of the Microsoft Windows 10 May 2019 Update, you may have noticed one particular change in your PC’s behavior more than the others: The update to Windows 10 Version 1903 now blurs the background image on the standard login screen. While not a big deal in the overall scheme of things, it is a “feature” that very few of us asked for.
If you would like to lose the blur effect on the login screen and go back to a clear background image, there are three suitable methods. One is a simple change to the Personalization Settings, while the other two involve editing the Windows Registry and modifying Group Policy settings, respectively.
This tutorial shows you how to reverse the new default setting of blurring the background on the standard Windows 10 Version 1903 login screen using three different methods.
SEE: Windows 10 May 2019 Update: 10 notable new features (free PDF) (TechRepublic)
How to disable the blur effect through the Personalization Settings
The blur effect created by the Windows 10 May 2019 Update is, in reality, a transparency effect and can easily be turned off through the Personalization Settings. Click or tap the Start Menu button in the lower left-hand corner of the Windows 10 desktop and select the Settings icon. Choose Personalization from the list of settings and select the Colors item found in the left-hand navigation menu.
Scroll down the page until you see Transparency effects, as shown in Figure A.

Figure A
Turn off transparency effects, and the next time you reboot your PC and log in, the blur effect will be gone–unfortunately, so will all other transparency effects common to the Windows 10 operating system. This may not be exactly the result you were looking to achieve. However, you do have alternatives.
How to disable the blur effect with an edit of the Registry File
Disclaimer: Editing the Windows Registry file is a serious undertaking. A corrupted Windows Registry file could render your computer inoperable, requiring a reinstallation of the Windows 10 operating system and potential loss of data. Back up the Windows 10 Registry file and create a valid restore point before you proceed.
If you would like to disable the blur effect, but only for the Windows 10 login screen, you can do it by editing the Registry File. Type “regedit” into the desktop search box and select the registry editor from the results. In the editor, navigate to this key:
HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindowsSystem
As you can see in Figure B, there are no values in the System folder, so we will have to create one.

Figure B
Right-click the System folder and select New | DWORD (32-bit) Value and give it the name DisableAcrylicBackgroundOnLogon. Double-click the new key and change its value to 1, and click OK, as shown in Figure C.

Figure C
This change will disable the blur effect from the Windows 10 login page but will maintain the remaining transparency effects found in the operating system.
How to disable the blur effect with Group Policy settings
If you have Microsoft Windows 10 Pro, you can disable the blur effect with the Local Group Policy Editor and avoid the hassle of editing the Registry File.
Type “group policy” into the Windows 10 desktop search box and select the editor from the list of results. In the editor, navigate to this folder:
Computer ConfigurationAdministrative TemplatesSystemLogon
In the right-hand list of settings, as shown in Figure D, find the Show clear logon background item.

Figure D
Double-click the Show clear logon background item to open the group policy settings screen shown in Figure E. Change the setting to Enabled, click OK, and you will have successfully disabled the blur effect from the Windows 10 login page.

Figure E
If you ever want to reenable the blur effect, navigate to the same group policy setting, and change it to Disabled.