On the effectiveness of local warping against SIFT-based copy-move detection

One of the simpler and most used method to alter the content of a digital image is to copy-move a portion of it onto another area with the intent, usually, to hide something awkward. In image forensics scientific community, this kind of modification is generally detected by resorting at techniques based on SIFT features that provide a local description which is robust to global geometric transformations the image may undergo. On such a basis, this paper investigates the effectiveness of some methodologies which introduce a local warping onto the copy-pasted patches in order to reduce the detection capability of SIFT-based approaches. This analysis is particularly interesting in a real scenario of forensic security. Four diverse local warping techniques have been taken into account and experimental results with respect to final perceptual quality of the forged image are presented