Eight-Scale Image Contrast Enhancement Based on Adaptive Inverse Hyperbolic Tangent Algorithm

• Published in: Algorithms Vol. 7; no. 4; pp. 597 - 607
• Main Authors: Yu, Cheng-Yi, Lin, Chi-Yuan, Yang, Sheng-Chih, Lin, Hsueh-Yi
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.12.2014
• Subjects: Adaptive algorithms; adaptive inverse hyperbolic tangent; Adjustment; Algorithms; Blurring; contrast enhancement; eight-scale; Extruding; Image contrast; Image enhancement; Inverse; sub-band; Tangents
• ISSN: 1999-4893; 1999-4893
• DOI: 10.3390/a7040597

The Eight-Scale parameter adjustment is a natural extension of Adaptive Inverse Hyperbolic Tangent (AIHT) algorithm. It has long been known that the Human Vision System (HVS) heavily depends on detail and edge in the understanding and perception of scenes. The main goal of this study is to produce a contrast enhancement technique to recover an image from blurring and darkness, and at the same time to improve visual quality. Eight-scale coefficient adjustments can provide a further local refinement in detail under the AIHT algorithm. The proposed Eight-Scale Adaptive Inverse Hyperbolic Tangent (8SAIHT) method uses the sub-band to calculate the local mean and local variance before the AIHT algorithm is applied. This study also shows that this approach is convenient and effective in the enhancement processes for various types of images. The 8SAIHT is also capable of adaptively enhancing the local contrast of the original image while simultaneously extruding more on object details.