Segment the Nuclei into a Separate Image
% Notice that there are dark and light blue objects in one of the clusters.
% You can separate dark blue from light blue using the 'L*' layer in the
% L*a*b* color space. The cell nuclei are dark blue.
%
% Recall that the 'L*' layer contains the brightness values of each color.
% Find the cluster that contains the blue objects. Extract the brightness
% values of the pixels in this cluster and threshold them using |im2bw|.
%
% You must programmatically determine the index of the cluster containing
% the blue objects because |kmeans| will not return the same |cluster_idx|
% value every time. You can do this using the |cluster_center| value,
% which contains the mean 'a*' and 'b*' value for each cluster. The blue
% cluster has the smallest cluster_center value (determined
% experimentally).
% Use the mask |is_light_blue| to label which pixels belong to the blue
% nuclei. Then display the blue nuclei in a separate image.