A hybrid method for contrast enhancement

Abstract

One of the most important aspects of image quality is contrast and this paper presents a new hybrid method for contrast enhancement. The proposed method is a combination of two basic contrast enhancement methods i.e. transform and histogram. At first we apply Nonsubsampled Contourlet Transform (NSCT) on the source image, then NSCT coefficients are mapped to fuzzy domain and modified by a mapping function in fuzzy domain. After transforming the modified membership values from fuzzy domain into frequency domain, the enhanced image is reconstructed from the modified NSCT coefficients by inverse NSCT. Finally, histogram of the image is equalized by Contrast Limited Adaptive Histogram Equalization (CLAHE). The experimental results show that our method can achieve higher improvement than both Contourlet Transform (CT) and Histogram Equalization (HE) contrast enhancement methods.