Functions and graphs: Relations and functions
Example 3: Colour models
Also in computer science applications you may encounter many mathematical relation between quantities. The following example of a linear relation between four variables originates from conversion of colour models.
The relation between the gamma-corrected Luma signal \(Y'\) (perceived brightness) for HDTV and the gamma-corrected RGB signals \(R\,',G\,',B\,'\) is according to the BT.709 standard equal to
\(Y'=0.2125R\,'+0.7154G\,'+0.0721B\,'\)
In the above specific formula we call \(R'\), \(G'\) and \(B'\) independent variables, because each is a variable whose value can be freely chosen. The signal \(Y'\) is the dependent variable, because its value depends on the values of the independent variables. The Calculus module is limited to functions of one variable; functions of two or more variables are discussed in the Advanced Calculus module
