An improved anti-forensic technique for JPEG compression

Abstract

The availability of numerous powerful image processing tools or software makes it easier to manipulate the digital information without the addition of any footprints. JPEG compression based tampering detectors are generally employed in digital image forensics. An efficient anti-forensic technique is required to measure the capability of JPEG forensic detectors. In this article, an efficient JPEG anti-forensic technique is presented to hide the JPEG compression artifacts in spatial as well as Discrete Cosine Transform (DCT) domain. We initially employ shifted block DCT approach on the considered JPEG compressed image to fill the gaps in the comb-like distribution of DCT coefficients. This shifted block DCT approach led to the addition of dithering noise itself without the need of any adaptive dithering model. Therefore, the computational cost to create a JPEG forgery reduces significantly. The result of this shifted block DCT approach is further processed in the second step by TV (Total variation)-based deblocking operation to remove the blocking artifacts left during the JPEG compression in the spatial domain. The experimental results illustrate that the presented approach has better performance in comparison to the existing techniques in terms of image visual quality and forensic undetectability with highly reduced computational cost.