Manually Loading Profiles

Many Linux systems use the Color Daemon (colord) for managing color profiles. Some desktop environments offer GUI tools that act as an interface to colord, such as the Gnome Color Manager tool. The other option is to load the profile using a command-line tool such as xcalib:

xcalib profile_name.icc

xcalib is a "tiny monitor calibration tool" for X Window and MS Windows environments. The author describes the tool as "postcardware." (It has a GPL license, but the author requests you send him a postcard if you use it.)

See your local package manager for more on obtaining xcalib. With Arch Linux, the xcalib utility is contained in a separate package of the same name. You can also find the source code online [5]. The complete, not very meaningful documentation for the program is in a README file. xcalib requires profiles that contain the VCGT tag, which is always the case for the data generated with DisplayCAL.

If you have multiple screens, use the -s option to specify the number of the screen that will receive the profile. (Screen 0 is the default if you don't specify the -s option.)

The command from the first line of Listing 1 loads the specified profile for the display 1, an additionally connected monitor.

With xcalib, you can use the -a option to change loaded profiles during operation. The argument for one of the basic colors (-red, -blue, or -green) is three values: the gamma from 1 to 5, the brightness in percent, and the contrast in percent (Listing 1, second line). The adjustments remain active until they are switched off, unless you explicitly delete them using the -c option.

To automatically launch xcalib, use the bash configuration script .bashrc or call a script using the desktop's autostart mechanism.

If you have problems with xcalib, you can use the xicclu utility from the Argyll package [6]. xicclu is similar to xcalib but provides some different options. One disadvantage of xcalib is that it does not automatically detach itself from the terminal.

Conclusions

For users who are serious about editing images, it is definitely worth the time to create a profile of the monitor at least once. The result is always surprisingly positive, and the higher the monitor's quality, the more satisfying it is. Photos from the expensive SLR cameras finally look good, and shade and light have structure. Whether you want to go to the effort of checking the monitor regularly and possibly investing in a better colorimeter depends on your requirements. Normally, an annual recalibration run for a previously-profiled monitor is sufficient.