KMEANSK - mex implementation (compile by mex kmeansK.cpp
Also an equivalent MATLAB implementation is present in zip file

Performs K-means clustering given a list of feature vectors and k. The argument k indicates the number of clusters you want the data to be divided into. data_vecs (N*R) is the set of R dimensional feature vectors for N data points. Each row in data_vecs gives the R dimensional vector for a single data point. Each column in data_vecs refers to values for a particular feature vector for all the N data points. The output data_idxs is a N*1 vector of integers telling which cluster number a particular data point belongs to. It also outputs centroids which is a k*R matrix, where each rows gives the vector for the cluster center. If we want to segment a color image i into 5 clusters using spacial and color information, we can use this function as follows:

% r = i(:,:,1);
% g = i(:,:,2);
% b = i(:,:,3);
% [c r] = meshgrid(1:size(i,1), 1:size(i,2));
% data_vecs = [r(:) g(:) b(:) r(:) c(:)];
% [ data_idxs centroids ] = kmeansK( data_vecs, k );
% d = reshape(data_idxs, size(i,1), size(i,2));
% imagesc(d);