No dimming on Ubuntu 13.04 with 64-bit, standard AMD/ATI drivers

Hej! Does xgamma produce any result? I suppose it won't since f.lux doesn't work either. In this case it is a problem with the X server or the graphics driver not supporting gamma corrections.

That sounds plausible, because I used to run the proprietary AMD driver and now it's the default built-in driver - clearly they work differently. I'll check "xgamma" and post results (probably tomorrow).

Here's the xgamma output. I can't tell from this whether xgamma is always running in the background, or whether it just started to give me a response and then ended again -- but at least it proves that it's there and it's functional:

torben@torben-desktop:~$ xgamma
-> Red 1.000, Green 1.000, Blue 1.000
torben@torben-desktop:~$

Sorry what I meant was: are you able to change the screen gamma correction
using xgamma? Redshift and xgamma are using the same method. You have to
run xgamma with some parameters other than 1.0 to tell.

Well, I can change the gamma setting but the display does not change regardless what value I set:

torben@torben-desktop:~$ xgamma -gamma 0.7
-> Red 1.000, Green 1.000, Blue 1.000
<- Red 0.700, Green 0.700, Blue 0.700
torben@torben-desktop:~$ xgamma
-> Red 0.700, Green 0.700, Blue 0.700
torben@torben-desktop:~$ xgamma -gamma 0.2
-> Red 0.700, Green 0.700, Blue 0.700
<- Red 0.200, Green 0.200, Blue 0.200
torben@torben-desktop:~$ xgamma -gamma 2.2
-> Red 0.200, Green 0.200, Blue 0.200
<- Red 2.200, Green 2.200, Blue 2.200
torben@torben-desktop:~$ xgamma
-> Red 2.200, Green 2.200, Blue 2.200
torben@torben-desktop:~$ xgamma -gamma 1
-> Red 2.200, Green 2.200, Blue 2.200
<- Red 1.000, Green 1.000, Blue 1.000
torben@torben-desktop:~$

Then redshift won't be able to change the display either. Your X server or graphics driver does not support gamma corrections apparently.

Godt, mange tak! Now I know what needs to be fixed. I'll try installing the proprietary AMD graphics drivers, that's what used to work on the old machine too.

I've just installed the latest ATI driver (http://askubuntu.com/questions/74171/is-my-ati-graphics-card-supported-in-ubuntu) and now gamma adjustments work: the command "xgamma -gamma 1.5" makes the screen change color.

Hmm, still not working. As noted, I've got a gamma-capable driver installed now but the "toggle" menu option doesn't change the screen even though it's nearly midnight now. What else can I do to identify the problem?

Maybe you could try "redshift -O 4000" (capital o) to see if redshift is able to change the gamma setting. If it is, then your location is probably not set up correctly.

Not sure I understand this output:

$ redshift -O 4000
Gamma ramp size too small: 0
Failed to start adjustment method randr.
Trying next method...
Using method `vidmode'.
$

The "randr" method for changing gamma setting is giving an error (it is probably not implemented by the driver), so redshift is trying the next best method ("vidmode"). Does it change the color?

Undskyld, I hadn't realized that the -O switch was supposed to change the color (I've read the -h output now and am wiser). No, that command did not change the screen's color temperature.

Also, I tried the exact command from your website:
$ redshift -l 55.7:12.6 -t 5700:3600 -g 0.8 -m vidmode -v
and while the verbose output shows that it runs, the screen still doesn't change despite forcing the vidmode method.

I've just discovered that something must've changed between post #8 and #9 on this page, because in post #8 I confirmed that "xgamma -gamma 1.5" makes the screen change color, but when I try that now, it no longer works.

I'm using the AMD proprietary driver "fglrx". I'll now try a regular reboot first and see if that helps., otherwise I'll try switching to "fglrx-updates" instead, and the built-in open source drivers as a last resort.

Will report findings afterward.

(scratching my head) Well, who said you never need to reboot Linux? :-)

I'm still using the AMD proprietary driver "fglrx" and now it "just works", and it's even using "randr" to do it. Now all commands "xgamma" and "redshift -O 4000" and "redshift -l 55.7:12.6 -t 5700:3600 -g 0.8 -m vidmode -v" work as expected. I honestly have no idea why, but I'm happy.

If I'm feeling really adventurous I might still test those other drivers. But right now I'd rather enjoy the screen.
Undskyld besværet, og mange tak for din tålmodige hjælp!

For the record the same error message and behaviour appears when running redshift-gtk in a Virtual Machine (Virtulabox 5.1.20):

Failed to run Redshift
Gamma ramp size too small: 0
Failed to start adjustment method randr

Running the command 'redshift -O 4000' returns the same message.
Running the command xgamma -gamma 1.5 returns no error message but does not modify the actual virtual machine display gamma.