What is wrong?

$ xrandr --output HDMI-1 --gamma 0.6:1.0:1.6 --brightness 0.76
$ xrandr --verbose | sed -n '/HDMI-1/,/Brightness/p'
HDMI-1 connected 1920x1080+0+0 (0x6c) normal (normal left inverted right x axis y axis) 510mm x 290mm
    Identifier: 0x63
    Timestamp:  65733000
    Subpixel:   unknown
    Gamma:      1.7:1.0:0.63
    Brightness: 0.75
  • I can confirm the bug has same results for me using Ubuntu 16.04.5 LTS and kernel 4.4.0-135-generic. Commented Sep 29, 2018 at 0:44

1 Answer 1


This bug report filed in 2017 links to 2010 first report:

The good news is the bug was fixed in August 2019. The bad news is the fix in version 1.5.1 hasn't made it into Ubuntu yet which (on my system at least) is still on version 1.5.0.

The work around I've used is to set gamma to the value you want. Read back the gamma setting which is inverted and then set gamma to those values. After the bug is fixed your work around still works but is unnecessary as it is setting the same values twice for R-G-B.

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