Histogram equalization is a well-known effective technique for improving the contrast of the images. However, the traditional histogram equalization (HE) method usually results in extreme contrast enhancement, which causes the unnatural look and visual artifacts of the processed image. In this paper, we propose a novel histogram equalization method, which is composed of an automatic histogram separation module and intensity transformation module. Experimental results show that the proposed method not only keeps the shape features of the original histogram but also enhances the contrast effectively.