If you have upgraded to Windows 10 fall Creators update, the display brightness might be adjusted to 50% or higher level after each reboot and become lighter. That also causes eye strain indoor and drain the tablet’s battery quickly. You can pick up the appropriate brightness in the Settings app manually, or do that using a registry tweak.
How to change/backup screen brightness level in Windows 10 fall Creators update
* First make sure you have updated your display drivers to the latest version.
Find out the related GUIDs for each available power plan
* Type CMD in Start menu, right click on Command Prompt, and select “Run as administrator” from menu.
* Type the command:
and press Enter to execute the command.
* It will output all GUIDs for each available power plan:
GUID: 381b4222-f694-41f0-9685-ff5bb260df2e (Balanced) GUID: 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c (High performance) GUID: a1841308-3541-4fab-bc81-f71556f20b4a (Power saver)
Note the GUID of the power plan you want to modify the screen brightness.
Then change Screen Brightness in Registry editor
* Press Win + R from your keyboard, type regedit, and click OK button.
* Navigate to the location below:
* Under the PowerSchemes folder, all sub-folders are the available GUIDs of each power plan.
* For example, I would like to change the Balanced power scheme, so I doube click on 381b4222-f694-41f0-9685-ff5bb260df2e.
* Then expand the key tree to the sub-key:
If you don’t find the key, just create it.
* Go to its right side pane, and you need to modify two keys:
ACSettingIndex: used to set the the screen brightness level when plugged in.
DCSettingIndex: used to set the the screen brightness level when plugged in.
* Double click on ACSettingIndex, configure its value data from 0 to 100 (like type 80), and click OK to save changes. Repeat the same way with DCSettingIndex. On my Surface Pro 4, I setup them to 80% and 60% respectively in my production environment.
* You can export the current Registry editor’s data as a backup file. if you re-install the Windows 10 in the future, simply import the file to restore the Screen Brightness settings.