Comments on “Hierarchical Suppression Method for Hyperspectral Target Detection”

The hierarchical constrained energy minimization (hCEM) algorithm, published in TGRS, has received more attentions in the field of hyperspectral target detection since publication. Using the classical CEM detector as the basic unit, it designs hierarchical structure to gradually suppress the background and to enhance the target detection performance. The authors claimed that the convergence of the hCEM algorithm can be theoretically guaranteed by analyzing the relationship between different layers of the hierarchical output. However, after some investigations, we found that the key formula presented in this letter is theoretically defective. This implies that the theoretical results do not hold and the convergence of the algorithm cannot be ensured.