Contrast enhancement using adaptively modified histogram equalization

A new contrast enhancement method called adaptively modified histogram equalization (AMHE) is proposed as an extension of typical histogram equalization. To prevent any significant change of gray levels between the original image and the histogram equalized image, the AMHE scales the magnitudes of the probability density function of the original image before equalization. The scale factor is determined adaptively based on the mean brightness of the original image. The experimental results indicate that the proposed method not only enhances contrast effectively, but also keeps the tone of the original image.