| Contrast enhancement is one of the most important issues in image processing, pattern recognition, and computer vision. The methods of contrast enhancement are mainly divided into two categories: indirect methods and direct methods. Indirect approaches of contrast enhancement largely map the original intensity values to new values based on histogram, and they just use global information generally. The direct approaches of contrast enhancement methods enhance the image by defining contrast and enhancing the contrast, utilizing both global and local information.; Wavelet transform is a popular tool in multi-resolution manner for signal analysis. In this paper, we propose a novel contrast enhancement approach based on wavelet transform. The proposed approach utilizes wavelet transform to decompose the image, and then, modifies the coefficients to achieve contrast enhancement. The experimental results demonstrate that the method is very effective and efficient in contrast enhancement without under-enhancement and over-enhancement. |
