Abstract: Nowadays use of Contrast Enhancement in Digital Images is on the verge of rise and the issue of current research. Many techniques under Image contrast enhancement have come into existence in previous years, but there is need of some techniques which must be very efficient and removes the drawbacks of previously used methods. As digital images or photos have been widely used as evidence in investigation field, medical, historical records, reports of journalist etc. Also with this the availability of most powerful tools which are capable of easy modification, manipulation, forgeries to image becoming quite easier. This paper is based on the study of different contrast enhancement techniques used in previous years and the methods they used. Also it explains the proposed methodology which uses non linear pixel mapping that introduce artifacts into an image histogram, and then detecting locally applied contrast enhancement in image , detecting histogram equalization in image and one image security algorithm is also used to add more security.

Keywords: Contrast Enhancement, Histogram Equalization, Peak-gap, encryption.