|PCA (Pairwise Clustering Algorithm) – Hierarchical Agglomerative Method|
|1) Initially each color (data) is a cluster.|
|2) At each step we find the most similar pair of clusters. Merge these two clusters into one cluster.
The chosen pair is the one that corresponds to the minimal value achieved by the distance function. Its value has to be computed between all pairs.
|3) Stop when obtain the desired number of colors.|