A Reversible Contrast Enhancement Using Digital Watermarking Based on Histogram Modification

Abstract

Recently, Wu et. al have proposed a reversible contrast enhancement using digital watermarking. By reversible processing, it is possible to restore the original image from the contrast enhanced image. However, there is a problem that visible noise occurs in the contrast enhanced image This noise is caused by the pre processing to avoid the overflow or underflow of the luminance value. In this study, we propose a method to improve the image quality of contrast enhanced images by improving pre processing In our method, two adjacent bins with low occurrence frequencies are combined to make empty bins around the range boundary .