Can we trust digital image forensics?

Abstract

Compared to the prominent role digital images play in nowadays multimedia society, research in the field of image authenticity is still in its infancy. Only recently, research on digital image forensics has gained attention by addressing tamper detection and image source identification. However, most publications in this emerging field still lack rigorous discussions of robustness against strategic counterfeiters, who anticipate the existence of forensic techniques. As a result, the question of trustworthiness of digital image forensics arises. This work will take a closer look at two state-of-theart forensic methods and proposes two counter-techniques; one to perform resampling operations undetectably and another one to forge traces of image origin. Implications for future image forensic systems will be discussed.

Source Camera Identification Using Non-decimated Wavelet Transform

“…The identification of a source device using SPN can be formulated as the following binary hypothesis testing: H 0 = Image was not created by camera H 1 = Image was created by camera (2) where H 0 is the null hypothesis and H 1 is the alternative hypothesis. The correlation match is performed between the camera reference SPN and each individual image SPN in the dataset.…”

“…Within the digital camera image creation pipeline, described in [1], artifacts are left in the created image at each processing stage. These artifacts can be from processing inside the device or characteristics of the device itself [2] and can be extracted as features from images in order to link to the source imaging device. Some of the artifacts from the camera pipeline that can be used for source device identification are demosaicing algorithm of Color Filter Array (CFA), quantization tables for JPEG image compression, EXIF header of JPEG image, lens aberration and sensor noise.…”

Mobile Camera Source Identification with SVD

“…The artefacts left behind in the digital image by the camera can be from the characteristics of the imaging device itself or the processing inside the device [6]. In general, forensic investigators do not have any previous knowledge about the source of the images they recover and digital image forensics usually works as a 'blind' approach without needing à priori knowledge about the images.…”

Digital image forensics: a booklet for beginners

“…The first attempt at fooling source device identification techniques was proposed by Gloe and others in [39]. The study proposes an attack to the identification method [65], which is based on the extraction and the analysis of the camera pattern noise (cfr.…”