“…In the early years, LIE was achieved by traditional image processing techniques, specifically value mapping methods, such as histogram equalization (HE) (Acharya & Ray, 2005;Kim, 1997;Pisano et al, 1998;Pizer et al, 1987;Reza, 2004;C.-C. Sun, Ruan, Shie, & Pai, 2005;Zuiderveld, 1994) and gamma correction (GC) (Guan, Jian, Hongda, Zhiguo, & Haibin, 2009;Huang, Cheng, & Chiu, 2012;Singh, Kumar, Balyan, & Singh, 2017;W. Wang, Sun, & Ng, 2019).…”