How Monitor Profiles Work

15th September 2015 Colour Management & Lighting


We recommend that before reading this article, you have a look at our article on Calibration Versus Profiling so you have a stronger understanding of what is being discussed.

With monitor calibration, it can be hard to differentiate between the calibration part of the process and the profiling part of the process. Generally, when you're actually going through the software, it is more obvious. When you are calibrating your monitor, it asks you to make physical adjustments to the monitor's controls, and then when the colour patches flash up on screen and are measured, the device is building the monitor profile.

Colour management of a monitor is a complex mix of calibration curves and a set of translation tables.

At least, that is how it seems. In actual fact, the colour management of a monitor is a complex mix of calibration curves (stored either in the LUT (look up table) of the video card with traditional monitors, or in the LUT in the back of better monitors that offer direct hardware calibration) and a set of translation tables. For colour accuracy to work in full, the calibration curves must be installed in the video card/monitor LUT, and the operating system must supply the monitor profile to applications that request it so that image colours can be remapped to monitor colours using the translation tables. So a monitor profile actually stores both physical calibration curves (in the 'vcgt' tags) and the translation tables (ie the 'profile' part).

It is only this combination of events that results in a fully calibrated and profiled monitor. If either process fails, that is the LUTs are not correctly loaded, or the profile is not correctly returned to calling applications by the operating system, then you will not have a fully colour managed environment.