Comment on: "Image thresholding using type II fuzzy sets"

This short comment aims at providing connections between the algorithm for image thresholding using type II fuzzy sets, recently proposed by Tizhoosh in Ref. [1], and Atanassov’s intuitionistic fuzzy sets (A-IFSs), as well as pointing out some terminological issues. The idea of applying higher-order fuzzy sets for image thresholding discussed in Ref. [1] is interesting and promising; however, some clarifications have to be stressed out regarding the underlying theoretical treatment of the proposed approach. Before proceeding, the basic definitions and concepts used throughout this comment are briefly presented.