Howto Lower brightness on Apple LCD Monitor? KUbuntu 10.4, KDE System Settings Display; jor XOrg

[Xavier Bestel]

On Wed, 2010-06-23 at 00:41 +0200, Éric Piel wrote:
> Op 22-06-10 23:56, giovanni_re schreef:
> > Didn't get an answer on KUbuntu list, so hopefully someone here might
> > have a suggestion.
> > 
> > ==
> > I've just installed an Apple Cinema Display (LCD) monitor. This is a 5
> > year old monitor.
> > Using KUbuntu 10.4
> > 
> > The apple website indicates this monitor has:
> > User controls (hardware and software):
> >   	Display power, system sleep, system wake, brightness and display tilt
> > http://support.apple.com/kb/SP79
> > http://support.apple.com/kb/SP77
> > 
> > Brightness is what I want to turn down.
> > 
> > Looking in the 
> > KDE System Settings > General > Computer Administration > Display > Size
> > & orientation > DVI-0
> > 
> > there is no adjustment for brightness.
> > 
> > Anyone know how to decrease brightness on this?
> > 
> > What sw manages the KDE system settings for Displays?  KDE? X?
> > 
> > Is there a way to turn down the brightness using some X config?
> > 
> > Is there a GUI for doing X configuration settings?
> 
> Why do you think you can change the brightness via software? It is very
> unsual for separate monitors to support this. Isn't there some buttons
> on the monitor to do that?!
> 
> Anyway, if you really want to do this by software:
>  * DDC/CI is the key. Try using ddccontrol. But your graphic card must
> support it, and your monitor too. In practice, it's unlikely to work.

Well, it works quite well on my Dell 24" (radeon driver), even if it has
front controls.
I think more monitors support this than you think. The problems are:
- KMS/Xorg don't support it, so you have to be root for ddccontrol to
work.
- Controls aren't standardized, so you have to play with the 255
possible controls to find the useful ones (e.g. brightness and color
temp).

	Xav