Splicing forgeries localization through the use of first digit features

One of the principal problems in image forensics is determining if a particular image is authentic or not and, if manipulated, to localize which parts have been altered. In fact, localization is basic within the process of image examination because it permits to link the modified zone with the corresponding image area and, above all, with the meaning of it. Forensic instruments dealing with copy-move manipulation quite always provides a localization map, but, on the contrary, only a few tools, devised to detect a splicing operation, are able to give information about localization too. In this paper, a method to distinguish and then localize a single and a double JPEG compression in portions of an image through the use of the DCT coefficients first digit features and employing a Support Vector Machine (SVM) classifier is proposed. Experimental results and a comparison with a state-of-the-art technique are provided to witness the performances offered by the proposed method in terms of forgery localization.