Photo forensics from JPEG dimples

Shruti Agarwal, Hany Farid
2017 2017 IEEE Workshop on Information Forensics and Security (WIFS)  
Previous forensic techniques have exploited various characteristics of JPEG compression to reveal traces of manipulation in digital images. We describe a JPEG artifact that can arise depending on the choice of the mathematical operator used to convert DCT coefficients from floating-point to integer values. We show that the more commonly used floor or ceiling operators (but not the round operator) introduce a periodic artifact in the form of a single darker or brighter pixel-which we term a
more » ... hich we term a dimple-in 8 × 8 pixel blocks. We describe the nature of this artifact, its prevalence in commercial cameras, and how this artifact can be quantified and used to detect a wide range of digital manipulations from content-aware fill to re-sampling, airbrushing, and compositing.
doi:10.1109/wifs.2017.8267641 dblp:conf/wifs/AgarwalF17 fatcat:67tgeh5gxnfkhdnbgwvsp27ipa