DCT and DWT Based Methods for Detecting Copy-Move Image Forgery: A Review

Abstract

Nowadays, as various image manipulation tools are available very easily. Any person having a little knowledge about these tools can doctor the available images. So digital images are no longer trusted. Computer graphics and digital photography have made the tampering over image easy to commit but hard to detect. Although various image forgery techniques are available but copy-move image forgery is one of the most hard to detect image forgery. In Copy-Move image forgery a segment from the original image is copied and after performing some manipulation over that, segment is pasted at some other location on the same image. This forgery is intended to hide noticeable information shown by the image or for adding information in original image to convey a wrong message. We cannot identify such forgery on the basis of incompatibilities present in an image because the copied segment is taken from the same image so the properties like noise, blur, texture, color palette remain similar to the original image. So, copy-move image forgery is a serious threat to Image forensic Investigators. Researchers have developed several methods for detecting such kind of forgery based on exhaustive search and block based methods. Block based method is more successful in detecting such kind of forgery due to its speed and less complexity. In this paper we discuss forgery detection techniques based on Discrete Cosine Transform and Discrete Wavelet Transform.