2.2. Color Models

We are all accustomed to the use of \(RGB\) values to represent colors. But then you may ask “what is the relation of \(RGB\) values and the \(XYZ\) color representation?” Most often the honest answer is that it is unknown. Do you use a color management systems on your computer and in your software? What is the color profile that you use? Did you calibrate your display? Probably the answer is no to all three questions.

Try the following experiment: open up a browser at this page on several laptops and place all laptops next to eachother so you can compare the images. Is the red Ferrari the same red on all screens? Probably not!

In this section we look at different ways to represent colors. These differences (“your RGB is different from my RGB”) are often the cause for color differences.

2.2.1. RGB Color Model

Life would be easy if we all had chosen long time ago that digital images were to be encoded with XYZ values. XYZ are device independent color coordinates, the X,Y and Z values are related to the universal standard of color encoding.