Note that:
- N
- number of pixels in an image
- K
- number of classes
- k
- index for the current class
- i
- index for the current pixel
- xi
- data in the i'th sample. xi is usually a vector.
- k(i)
- class to which xi belongs
- Ik
- set of i's which belong to class k
- nk
- number of elements in Ik
- ck = Sigma(i in I) (xi)/nk
- the center of the K'th class
- c = Sigma(k) nk ck/N = Sigma(i) ck(i)/N
- the center of the entire data set
N = Sigma(k) nk
Notation taken from [1]