Digital Image Analysis for Evidence: A MATLAB toolbox

In the last decade, affordable digital camera technology has become widely available, resulting in the proliferation of digital images. The creation, modification and distribution of certain photographic materials is controlled by law in the UK and in many other countries. For example, the production and possession of pornographic images of under 18s is prohibited in the UK by the Protection of Children Act 1978. It is similarly an offense to produce, modify and distribute any image that would be considered useful to a person committing, or preparing to commit, an act of terrorism under the Counter-Terrorism Act 2008. Digital image forensics is the science of determining the source of digital images and detecting the presence of image tampering (e.g. photo forgery). The majority of research in this area has been conducted in the last decade by a small number of experts in the field of digital image processing. An understanding of these methods requires in-depth knowledge of image processing algorithms which most researchers and educators in the broader field of computer forensics do not possess. In this paper we describe our Digital Image Analysis for Evidence (DIAnE) toolbox, written in the MATLAB programming language. Our approach is to utilise the inherent imperfections in image sensors that have previously been shown to produce consistent and unique noise patterns. The toolbox contains code libraries for generating device ’fingerprints’ that enable evidential images to be matched to their source cameras and graphical plots to facilitate easy understanding of the resulting correlation data. We believe DIAnE to be the only available MATLAB toolbox that performs this role.