Adaptive contrast enhancement using modified histogram equalization

Adapted enhancement controlled contrast using adjusted histogram is developed to minimize the problems of over enhancement, saturation artifacts and change in mean brightness with conventional histogram equalization. The input image's histogram is first divided into four sub-histograms based on its median. A clipping process based on the input image mean is applied. Then each partitioned histogram is equalized independently. A contrast enhancement rate is devised in order to achieve the varying contrast for output images. The proposed algorithm is proved to produce better enhanced images than the contemporary techniques in terms of contrast per pixel and structural similarity index. (C) 2015 Elsevier GmbH. All rights reserved.