Countering anti-forensics to wavelet-based compression

Abstract

Wavelet-based compression is widely used to reduce image redundancy for efficiently storing and transmitting the data. Thus it is an important part in digital image forensics to trace the wavelet-based image compression history. The wavelet-based compression leaves comb-like quantization artifacts in the DWT (Discrete Wavelet Transform) histogram, which however can be disguised using a proper dithering operation. In this paper, standing on the forensic side, we study the joint histogram of DWT coefficients across different levels, whose pattern is robust across a wide range of natural uncompressed images but can be easily destroyed by the waveletbased compression or the dithering operation used for anti-forensic purposes. By applying the Hough transform to the joint DWT histogram, we derive a 12-dimensional feature vector and a merged discriminating feature. Experimental results demonstrate the effectiveness of the proposed method for differentiating uncompressed images from (anti-forensic) wavelet-based compressed images.

Digital Image Forensics and Counter Anti-forensics

“…Anti-forensics for JPEG compression is countered by the work in [24] which uses inter-and intra-block correlations. Anti-forensics developed for wavelet-based compression techniques is countered in [25] by analyzing relations between DWT coefficients across different levels.…”

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

“…The features are then used to train a SVM classifier. The results on benchmark databases showed that this scheme is capable of detecting JPEG measures grainy noise due to anti-forensic dither in DCT domain using TV, accuracy almost 100% over QF ∈ [30,84] Wang et al [126] 2014 quantisation UCID [78](1338 greyscale 512×384 images, compression rate from 0.5 to 8bpp, SVM, JPEG2000, SPIHT)…”

“…Wang et al [126] proposed an AAFT for wavelet-based compression. The fingerprints of counter-forensics wavelet-based compression were suppressed by analysing relationships of DWT coefficients across different decomposition levels.…”