Multi-modal Images Contrast Enhancement Using Histogram Specification with Gamma Distribution

Contrast enhancement occupies an important part of image enhancement area [1]. This paper proposed a contrast enhancement method which is based on the modification of image’s histogram using histogram specification (HS) and Gamma distribution. In fact, this work aims to complete the work of Al-Manea and El-Zaart [2] to include multi-modal images since their work can deal only with bi-modal images. The proposed method in this paper begins by reading the image and getting the statistical information of the original histogram using maximum likelihood Gamma distribution (MLGD). Then, it generates the desired histogram by separating image modes using several shifting processes applied on each two successive modes. At the end, it generates the enhanced image using HS. Finally, the proposed method has been implemented and tested using various multi-modal gray-level images where experimental results showed an improvement in the contrast of these images.