Counter-forensics of median filtering

Median filtering is a well-known non linear denoising filter often used as an harmless post-processing, sometimes also employed to affect the reliability of some forensic techniques. In this work, we present a novel counter-forensic method able to conceal the characteristic traces left by median filtering. By exploiting the knowledge of features used in existing median filtering detectors, we are able to remove the characteristic footprints via suitable random pixel modification, while keeping the quality of the counter-attacked image high. Experimental results show that the proposed method is very effective, computationally efficient and competitive with other state-of-the-art techniques.