Greyscale is a quick settings tile for Android which allows you to toggle a device between colour display and greyscale.
In order to use Greyscale, you must manually grant it the
WRITE_SECURE_SETTINGS
permission, since this permission is not normally available to third party
apps.
This can be done through adb by running the following from the command line:
adb shell pm grant io.github.rsookram.greyscale android.permission.WRITE_SECURE_SETTINGS
If you later wanted to remove the permission, you can run:
adb shell pm revoke io.github.rsookram.greyscale android.permission.WRITE_SECURE_SETTINGS
Once this is done, adding the quick settings tile is all that's left to do before you can use it.
This same option exists under Developer Options > Simulate color space, but
it's convenient to have a quick settings tile if you want to change it
frequently.
Also of note is that the APK is < 20 KB in size, and there are no third party dependencies used in the app.
This repository started in this fork and was turned into a standalone repository since almost all of the code had been changed since being forked.