Display contrast reduced while on battery mode on ThinkPad X220
When my ThinkPad X220 desktop background is black and no windows are opened (only the taskbar is shown), the screen appears to switch to a reduced display quality. The effect looks like a 256-color mode, raising the contrast to extreme levels so that colors of the taskbar look and all icons seem to be 'pixelated'.
When I then open a window, the screen needs up to 5 seconds to adjust. Within these 5 seconds, some colors are not clearly shown and menus and window title bars look weird.
It slowly adjusts until it looks normal again.
This is reproducible with a black desktop background (I needed to switch to a colorful background image to prevent this), but also sometimes noticable when opening the lid after leaving it closed for a while (not in standby).
I use the latest drivers from the Lenovo website, all utilities are installed, and I haven't changed anything in the Intel graphics settings.
This is a normal power-conservation feature built into the Intel HD Graphics driver. It can be disabled via the Intel Graphics Control Panel.
To disable it, right-click the desktop and select "Graphics Properties..." from the menu. Within the Intel control panel, select the Power tab on the left side, then select 'On battery' in the top right corner of the Power Source area. Finally, untick the checkbox next to "Display Power Saving Technology" to prevent contrast from being lowered.