max. brightness lower than under windows

Asbestbrezel · 2015-09-24 17:13:29

Hello arch folks,

For example this test-picture for screen calibration:

http://www.henner.info/just.htm

With windows i see a clear difference between the Field with 10 and the Background, If i switch to Linux without changing the settings of the Flatscreen-TV i see no difference between the both fields any more.

To change some values in the files that are found in /sys/class/backlight/intel_backlight does not show any effect.

Any idea?

Greetings,
Marcel

gnox · 2015-09-25 04:44:39

Maybe with xbacklight / gbacklight gives you finer control of the brightness.

pacman -Ss xorg-xbacklight
yaourt -Ss gbacklight

kokoko3k · 2015-09-25 06:28:41

Since it is generally not possible for a PC to change the backlight control of an external monitor/tv, i suspect your issue is due to a different calibration between windows and linux.
Also, on my little use of the microsoft product, i've seen drivers to automatically enable "dynamic contrast" function by default (on intel).

Anyway, just use a tool to calibrate your display.
Simple tools like xgamma or monica could do the trick.
More advanced LUT calibration tools include caled-git (in aur)

(EDIT: on my hdmi-connected tv, the screen brightness is different if i switch resolution, maybe you could check if the resolution used by arch is the same used under win)

Last edited by kokoko3k (2015-09-25 06:38:15)

R00KIE · 2015-09-25 13:03:25

kokoko3k wrote:

(EDIT: on my hdmi-connected tv, the screen brightness is different if i switch resolution, maybe you could check if the resolution used by arch is the same used under win)

And on the same note, also check (and compare) the refresh rate.

Asbestbrezel · 2015-09-25 20:00:45

I tried xorg-backlight, no effect. Its the same resolution and refresh rate, like in windows.

The windows-intel-driver has this driver-option-tool, where you can raise the brightness much more than about the normal windows-setting. You can turn it so hight, the screen is almost white. But the Linux seem not to have this option or, like its said in the wiki, it should be adjustable about /sys/class/backlight/intel_backlight/brightness.

But changing the values there, does not show any effect.

I tried xgamma and monica, they directly switch to the value 1.0 if try to put it higher.

Last edited by Asbestbrezel (2015-09-25 20:05:11)

kokoko3k · 2015-09-25 20:58:03

https://aur.archlinux.org/packages/caled-git/

Asbestbrezel · 2015-09-28 20:28:35

That finally works. Nice application, you made there. Thank you!

But i'm still wondering, why manipulation of the intel_backlight files does not show an effect, like discribed in the wiki https://wiki.archlinux.org/index.php/Backlight#ACPI

kokoko3k · 2015-09-28 20:40:54

it is generally not possible for a PC to change the backlight control of an external monitor/tv

Arch Linux

#1 2015-09-24 17:13:29

max. brightness lower than under windows

#2 2015-09-25 04:44:39

Re: max. brightness lower than under windows

#3 2015-09-25 06:28:41

Re: max. brightness lower than under windows

#4 2015-09-25 13:03:25

Re: max. brightness lower than under windows

#5 2015-09-25 20:00:45

Re: max. brightness lower than under windows

#6 2015-09-25 20:58:03

Re: max. brightness lower than under windows

#7 2015-09-28 20:28:35

Re: max. brightness lower than under windows

#8 2015-09-28 20:40:54

Re: max. brightness lower than under windows

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