Modify the default monitor brightness in the X server configuration (xorg.conf)

This document (7004105) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Desktop 11 (SLED 11)
SUSE Linux Enterprise Server 11 (SLES 11)
openSUSE 11.1

Situation

Default monitor brightness is not optimal.  This situation has come up when the monitor has minimal manual configuration settings or is difficult to access.

Resolution

The gamma settings for red, green, and blue can be increased or decreased in the X server's configuration file which is "/etc/X11/xorg.conf".

One important note to remember is that any direct modification to the xorg.conf file can be overwritten if the sax2 configuration utility is run.  Be sure to keep a backup of your modified xorg.conf file or at least keep good track of any changes made to the file so you can recreate the changes if needed.

The first step is to determine what setting will be best.  There is a command line tool that can be used to modify the gamma settings while you are logged into your graphic desktop so you can see the results immediately.  It is xgamma.  Here's an example:

xgamma -gamma 0.8

The default gamma setting is 1.0 so 0.8 would reduce the brightness a bit.  Valid settings are from 0.1 to 10.0.  Results and ability to use the settings are totally dependent on the graphics driver so some experimentation will be necessary to get the best results.

After finding the best setting it can then be placed in the xorg.conf.  While logged in as the root user, use your favorite editor to edit "/etc/X11/xorg.conf".  Locate the "Monitor" section and add the following line to the bottom of the section:

gamma 0.8 0.8 0.8

Of course, change the "0.8" to the setting that was discovered to be optimal for the monitor being used.

The setting is entered three times and corresponds to the gamma setting for the primary colors red, green, and blue.

A restart of the X server (init 3 then init 5) or a reboot will be required for the setting to take effect.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7004105
  • Creation Date: 05-Aug-2009
  • Modified Date:03-Mar-2020
    • SUSE Linux Enterprise Desktop
    • SUSE Linux Enterprise Server

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