A Tailored Anti-forensic Technique for Digital Image Applications

Abstract

The influence of digital images on modern society is incredible, image processing has now become a significant component in almost all the areas. But storing images in a safe and sound way has become very complicated. Sometimes, for processing we can only use raster bitmap format. Therefore processing of such images should be carried out without knowledge of past processing on that image. Even though many image tampering detection techniques are available, the number of image forgeries is increasing. Therefore it is important to find the weaknesses of offered detection methods to prevent further forgeries. In this paper, a new approach is designed to prevent the bitmap compression history. Then it also explains how this can be used to perform unnoticeable forgeries on the bitmap images. It can be done by the estimation, examination and alteration in the transform coefficients of image. The existing methods for identification of bitmap compression history are JPEG detection and Quantizer estimation. The JPEG detection is used to find whether the image has been previously compressed. But the proposed method indicates that proper addition of noise to an image's transform coefficients can adequately eliminate quantization artifacts which act as indicators of JPEG compression. Using the proposed technique the modified image will appear to have never been compressed. Therefore this technique can be used to cover the history of operations performed on the image in the past and there by rendering several forms of image tampering.

Bibliography of digital image anti‐forensics and anti‐anti‐forensics techniques

“…The technique resulted in degradation of image quality. The work proposed in [98] is an extension of JPEG compression anti-forensic technique presented in [77,80] using a bitmap image as the test image. Noise is added to the DCT coefficients based on the assumption that pixel differences within and across blocks are almost the same if no compression is done.…”

Digital Image Forensics and Counter Anti-forensics

“…Targeted and post-processing counter forensic techniques have been focused on much of the published works. Image compression has been widely explored for anti-forensics [15][16][17][18][19]. Targeting to fool DCT quantization artifacts-based classifier, [16] proposed addition of noise to the DCT coefficients to hide the JPEG compression history of a digital image.…”