Contrast enhancement using bi-histogram equalization via 2-D discrete wavelet transform

Abstract

The image enhancement process of a digital image is a part of digital signal processing which it plays an important role in some industrial segments, for instance, object classification or bio-identification, satellite exploration or aerial images, robot vision, cancer treatment, etc. These image applications are necessary to consume many resources in physical hardware and computer programming including the intelligent algorithm development of complexly advanced processing in order to enhance digital images – as well as be easy to analyse by humans. This research is aimed to present on Contrast Enhancement using Bi-Histogram Equalization via Two Dimensional Discrete Wavelet Transform (BHE2DWT) in order to compose the coefficient wavelet from other signals. At the end of the process, information on the approximation band from DWT will be divided into two sub-histograms, and then histograms will be independently equalized. After that resulting histograms will be decomposed by IDWT. Resulting images will be not only more displaying in high contrast than their original images, but also preserve the absolute mean brightness error (AMBE) to close their original images.