Anti-forensics of chromatic aberration

Over the past decade, a number of information forensic techniques have been developed to identify digital image manipulation and falsifications. However, recent research has shown that an intelligent forger can use antiforensic countermeasures to disguise their forgeries. In this paper, an anti-forensic technique is proposed to falsify the lateral chromatic aberration present in a digital image. Lateral chromatic aberration corresponds to the relative contraction or expansion between an images color layers that occurs due to a lenss inability to focus all wavelengths of light on the same point. Previous work has used localized inconsistencies in an images chromatic aberration to expose cut-and-paste image forgeries. The anti-forensic technique presented in this paper operates by estimating the expected lateral chromatic aberration at an image location, then removing deviations from this estimate caused by tampering or falsification. Experimental results are presented that demonstrate that this anti-forensic technique can be used to effectively disguise evidence of an image forgery.