Windows - turn off high contrast mode via GPO or script?

Question

I have a situation with a sizable deployment of Windows 10 computers and users who are turning on some truly horrific high-contrast themes, and then consuming IT resources because they can't change it back.

I'm aware that there's a keyboard shortcut to toggle this setting (Alt+Shift+Print Screen), but running around doing that or attempting user education are too resource intensive, and I'm aware of options to completely block access to the accessibility settings, but we have users with visual disabilities who require access to the ease of use settings that aren't malevolent, so that's not an option. I'm also aware of the options to prevent a user from changing their theme, but before doing so, I need to get rid of this high-contrast theme garbage.

Does anyone know of a way to simply toggle the high contrast theme off via a script or GPO?

Solution

The only way I was able to solve this is to load another "Theme" in windows. To do this, I created a login script that loads the default windows theme, the script contains the following:

@echo off
C:\Windows\resources\Themes\aero.theme

Loading a theme this way did indeed reset the high color contrast settings at login, but it opened a control panel window at each login, so I changed it to:

@echo off
C:\Windows\resources\Themes\aero.theme
taskkill /F /IM systemsettings.exe

The new line killed the control panel window after applying the new theme.

Comments

[Admin]

In Preference, Registry Item, pushing HKCU\CONTROL PANEL\ACCESSIBILITY\HIGHCONTRAST Flags=126 tried?

[Admin]

@yagmoth555 Nope. Let me try that.

[Admin]

@yagmoth555 Well, that seems to be part of it. That's the right value for the high contrast theme being off, but changing that registry value doesn't undo the horrors of the high contrast theme.

[Admin]

I only see a way to simulate a click then, but I tested some command like that and it didnt work; rundll32.exe %SystemRoot%\system32\shell32.dll,Control_RunDLL %SystemRoot%\system32\desk.cpl desk,@Themes /Action:OpenTheme /file:"C:\Windows\Resources\Themes\aero.theme" , I used to modify the aero.theme with the content of C:\Windows\Resources\Ease of Access Themes\hc1.theme to remove some settings, like HighContrast=1 to HighContrast=0, but no success. Maybe it's a path to check if it can work out somehow

[Admin]

See this post and the first comment.

[Admin]

@Ploni Nope, that guy offers three ways to permanently disable the accessibility features. Not to revert high contrast.

[Admin]

@HopelessN00b Option 1 & 3 permanently disable only the high Contrast theme.

[Admin]

@Ploni But they do not revert it once set, which is what I'm looking to do. Nor can I do this without on account of our users with visual disabilities, at least one of whom uses the high contrast theme in order to be able to see her screen.