Image contrast enhancement using unsharp masking and histogram equalization

Contrast enhancement and Mean brightness conservation are two important parameters of image enhancement. A high contrast image is good in subjective quality assessment but also high contrast may cause over or under enhancement in the enhanced image. In this paper a new unsharp mask filtering technique with the combination of histogram equalization is used for the general-purpose images which maximizes the entropy of the image as well as controls the over and under enhancement by clipping the histogram of the image. After rigorous experimentation on standard data-set, it is observed that the information present in the image is highest in the proposed method i.e. the entropy value is highest and the mean brightness is also comparable with the other histogram based image enhancement methods. Mean opinion score(MOS) result shows that visual quality of the image is also better than existing methods.