Gamma or brightness is too high when unlocking

It’s possible that this is caused by XScreenSaver changing the hardware gamma for its fade to black effect. Although xgamma is deprecated, it seems to address the issue. Observe:

~ xrandr --verbose | grep -i gamma
    Gamma:      1.0:1.0:1.0
    Gamma:      1.0:1.0:1.0
~ xgamma
-> Red  1.664, Green  1.664, Blue  1.664

Simply run xgamma -gamma 1.0.

Press Ctrl+Shift+L to lock the screen. Unlock the screen by entering your password. The brightness should be normal.

Disable fade to black effect

Disabling fade to black will not address the gamma issue as any program that touches the hardware gamma will exhibit the same symptoms. However if you find the effect annoying, do:

  • Open up “Screensaver”
  • Click the “Advanced tab”
  • Under “Fading and Colormaps”, uncheck “Fade to Black when Blanking”

Conflict with xfce-screensaver

XFCE now ships its own screensaver application which is known to conflict with xscreensaver. In Settings, click on the Screensaver icon (the one with a starry background) then uncheck both the Enable Screensaver and Enable Lock Screen options. In Session and Startup under Application Autostart make sure to disable xfce-screensaver as well.