Here's the thing: The profile describes the monitor in it calibrated state. That's the key to the whole thing.
Actually, the profile describes the monitor in its current state, whether calibrated or not. But since a profile is normally written by a calibrator, a calibration has usually preceded it.
The point is that a profile doesn't do anything. It's just a description of a color space, just like the Adobe RGB.icc profile is a description of the Adobe RGB color space. The profile doesn't adjust anything. The application's color management engine does that, based on the description. The profile is loaded by the application at startup.
The profile is very sophisticated. It accounts for irregularities in the tone response curve, and it describes the exact position of the three primaries. This is what determines how individual colors are reproduced - how saturated, how orangeish or magentaish a red color reproduces.
A calibration is a much simpler thing, not very sophisticated at all. It basically adjusts the white point, and then aligns R=G=B relative to that white point. If it's a good calibrator it can also define a black point. It also sets a general tone response curve (gamma) - but this will be remapped by the profile and "invisible" in a color managed environment, where the end result is always fully linear. Without color management, monitor gamma has to cancel out gamma encoding in the file.
In short - the profile has a much higher precision level than the calibration.
Since the profile has to reflect actual monitor behavior, that means any change in monitor response invalidates the profile, and you have to make a new one. That's why it's a good idea to have a calibrator. It's not a one-time thing, you need to do it again from time to time.
13
Replies
AdChoices