“…Statistical estimators of all sorts, spatial adaptive filters, transform‐domain methods, splines [1–3], stochastic analysis, total variation (TV) methods [4, 5], and other approximation theory methods, morphological analysis, order statistics, and more are some of the many directions explored in studying this problem. Sparse and redundant representations based methods [6, 7], as well as non‐negative matrix factorisation technique [8], are very important progress in image denoising problem in the past decade and have been widely used [9–13]. Non‐local means (NLM) [14, 15] and block matching 3D (BM3D) algorithm [16, 17] use non‐local self‐similarity to separate image and noise.…”