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fargred
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Joined: 19 Oct 2010
Posts: 29

PostPosted: Sun Jan 27, 2013 12:53 pm    Post subject: Change LCD brightness (and also contrast) Reply with quote

Hello there!

I am trying to find utility that could work with any LCD monitor and set its brightness and contrast. High brightness hurt my eyes after 15 minutes of reading internets, but watching movies and other stuff on low brightness LCD is now kinda degrading for me, so I wanted to set up a new alias for MPlayer so it will set high brightness before watching and usual when MPlayer exits.

Googling gave me these two string
Code:
/proc/acpi/
/sys/class/backlight

and I enabled
Code:
CONFIG_ACPI_VIDEO=y
CONFIG_BACKLIGHT_LCD_SUPPORT=y
CONFIG_BACKLIGHT_CLASS_DEVICE=y

But /proc/acpi is still empty and /sys/class/backlight appeared but is empty too. I’m not sure of does ‘backlight’ option even work on non-integrated displays, but ACPI thing should provide 7 levels of brightness on any monitor that conform ACPI 2.0 and can into EDID.
I used to run various X utils like xcalib or xbacklight, but they do not seem to be working.
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audiodef
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Joined: 06 Jul 2005
Posts: 5190

PostPosted: Sun Jan 27, 2013 5:02 pm    Post subject: Reply with quote

What video card do you have?

I have a Gentoo "television" machine with an Nvidia card. I use Nvidia-settings via simple scripts to set the brightness and screen resolution automatically depending on what program I'm starting (Smplayer or Hulu.com in Firefox, for example).

If you don't have an Nvidia card, there might be something similar for the card you do have.
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Ant P.
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Joined: 18 Apr 2009
Posts: 2204
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PostPosted: Sun Jan 27, 2013 5:48 pm    Post subject: Reply with quote

app-misc/ddccontrol will work if it supports EDID.
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BillWho
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Joined: 03 Mar 2012
Posts: 1600
Location: US

PostPosted: Mon Jan 28, 2013 3:58 am    Post subject: Reply with quote

fargred,

From what I can see the /sys/class/backlight userspace is setup when a laptop mode is selected in X86 Platform Specific Device Drivers.

Code:
/usr/src/linux/drivers/platform/x86/msi-laptop.c: * available to userspace under /sys/class/backlight/msi-laptop-bl/.
/usr/src/linux/drivers/platform/x86/compal-laptop.c: *   /sys/class/backlight/compal-laptop/
/usr/src/linux/drivers/platform/x86/fujitsu-laptop.c: * available to userspace under /sys/class/backlight/fujitsu-laptop/.

I'm not sure if you can enable any of these on a desktop.
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fargred
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Joined: 19 Oct 2010
Posts: 29

PostPosted: Mon Jan 28, 2013 10:00 am    Post subject: Reply with quote

audiodef wrote:
What video card do you have?

I have a Gentoo "television" machine with an Nvidia card. I use Nvidia-settings via simple scripts to set the brightness and screen resolution automatically depending on what program I'm starting (Smplayer or Hulu.com in Firefox, for example).

If you don't have an Nvidia card, there might be something similar for the card you do have.

The brightness that is set through nvidia-settings is not what I meant. It makes bright just the image itself. Here are three shots from my phone camera:

‘Internet’ preset
‘Movie’ preset
(you may not notice the actual difference between those two because camera’s white balance was automatically adapted to monitor brightness, but totally white screen on such brightness will starting to hurt your eyes in a minute)
…and ‘Internet’ preset with brightness and contrast in nvidia-settings set to values, similar to preset ‘Movie’.
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fargred
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Joined: 19 Oct 2010
Posts: 29

PostPosted: Mon Jan 28, 2013 10:05 am    Post subject: Reply with quote

Ant P. wrote:
app-misc/ddccontrol will work if it supports EDID.

ddccontrol cannot find my monitor.
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