“…The approaches, including the traditional histogram equalization method (HE), 27 contrast limited adaptive histogram equalization method (CLAHE), 28 the image enhancement algorithm based on nonsubsampled shearlet transform and guided filtering (NSST-GF), 20 the edge-based texture histogram equalization method (ETHE), 29 the dominant orientation-based texture histogram equalization method (DOTHE), 29 the feature-linking model for image enhancement (FLM), 30 the linking synaptic computation network for image enhancement (LSCN), 31 are applied in this section as the comparison techniques. In this paper, the decomposition layer of NSST is 3, and the directions are 8, 16, 16 in scales from coarser to finer, respectively; the γ is set to 1.2 and the c is set to 0.5.…”