set up linear equation from 4 data file

Hi, I am new to matlab. I have 4 data file, rgb value. 4 data file represent different direction. For instance, one of the file represent 0 degree and another one is 90 degree. how can I set up a linear equation so as to find the rgb value for other degree?

[John D'Errico]

Totally confusing. Please explain in more depth. Give an example of what you have, and probably the result you would hope to achieve for that example. If you want help, then you need to make it as easy as possible to get a useful answer.