Black level too high after upgrade to 13.10

[Rob_H]

I've got an Intel HD 4000 video chipset. Since upgrading to 13.10, the black level being sent to my external LCD monitor is too high. Blacks are showing up as gray and colors look washed out in general. I've tried playing with monitor brightness/contrast, but even with them set all the way down, blacks are still not black. Any idea how to adjust this in Kubuntu? It's definitely something in software.

[Rob_H]

Fixed with some help from the never-not-awesome ArchWiki. Apparently this is a regression caused by some changes in the 3.9 kernel. The following xrandr command fixed it for me. Your output name may vary.

xrandr --output HDMI1 --set "Broadcast RGB" "Full"

To make the change permanent, create a script as root called /etc/lightdm/xrandr.sh with the following contents:

#!/bin/bash
xrandr --output HDMI1 --set "Broadcast RGB" "Full"

Then make it executable:

sudo chmod +x /etc/lightdm/xrandr.sh

Then tell the display manager (LightDM) to run it on startup by adding the following line to the end of /etc/lightdm/lightdm.conf:

display-setup-script=/etc/lightdm/xrandr.sh