Exposing digital forgeries in video by detecting double quantization
Weihong Wang, Hany Farid · 2009
We describe a technique for detecting double quantization in digital video that results from double MPEG compression or from combining two videos of different qualities (e.g., green-screening). We describe how double quantization can introduce statistical artifacts that while not visible, can be quantified, measured, and used to detect tampering. This technique can detect highly localized tampering in regions as small as 16 x 16 pixels.