JPEG compression anti-forensics based on first significant digit distribution

Traces left by lossy compression processes have been widely studied in digital image forensics. In particular, the artifacts produced by JPEG compression have been characterized and exploited both in forensic methods and counter-forensic attacks. In this paper, we propose a novel anti-forensic procedure, aimed at concealing the traces of single JPEG compression by recovering the original distribution of first significant digits (FSD) of the DCT coefficients. We analyze the performance of our method and compare it with anti-forensic attacks reported in the literature in terms of quality of the resulting image. In addition, we prove the effectiveness of our approach as counter-forensic processing by measuring its impact on the performance of two different forensic tools, applied after the anti-forensic action.