The first thing is to install the gnome-color-manager applet, using, for e.g., sudo apt-get install gnome-color-manager. This is the piece of software that will let you load and use ICC profiles. An ICC profile is a file that describes the color rendering of a given display device (it also applies to input devices such as scanners, but here let us focus on the screen as an output device). The data contained in an ICC file allows the operating system/display manager to transform colors so that they appear exactly as they should, or at least as best as possible.
Let us take the example from a previous post. If I display a black and white image on my laptop, it ends up quite bluish; for some reason, gray isn’t gray but blue:
This, of course, prevents me from using this laptop to process photos, because if I adjust colors to compensate for the blue bias of the screen, the resulting pictures will probably show as yellowish on a normal screen; clearly an unwanted result.
If it’s a table-top LCD screen, there are a number of settings one can adjust and normally one arrives at a moderately good result without too much effort. That is, gray color appears as gray, good contrast, and full dynamic range. I’ve explained how to do this without the pain before.
If you have a laptop screen, well, you’re out of luck because you just don’t have the color settings available on the laptop itself. You have to proceed using software (as you should anyway, even if you have an adjustable table-top LCD), and that software is your display manager’s color manager (Gnome in this post, but there are similar tools for OS X and Windows). But the color manager in Gnome is rather crude; it doesn’t let you edit color profiles yourself, only load existing profiles.
Profiles can be found with Google. You just have to look for your specific screen model and you’re likely to find (after some effort) the manufacturer’s ICC profile for your device. While technically, the ICC profile for your generic screen model is likely to be suboptimal as it was not produce from your specific screen, it will likely be much better than tweakin’ all those settings by hand. If you’re lucky, the ICC profile is on the CD (you know, that useless CD with drivers nobody uses) or in the operating system somewhere. Apple laptops are calibrated by the manufacturer and the ICC profile is found in the /Library/ColorSync/Profiles folder. Just copy the ICC profile from the OS X partition to somewhere on your Linux partition and voilà, instant calibration, gracieuseté of Apple.
After you load the right color profile, the bluish tint (or whatever your screen does) is rectified and the picture is displayed correctly: