what is class scatter matrix and within scatter matrix ?

to form a eigen analysis between this two matrix

[Image Analyst]

Can you explain further? Like do you have two classes and you want to indicate each class (cluster) on a scatterplot with a different color? Or you have a scatterplot and you want to know which data points are in each class by using k-means, or SVM or some other method to decide which point is in which class?