Every Shred Helps: Assembling Evidence from Orphaned JPEG Fragments

Emre Durmus, Paweł Korus and Nasir Memon

IEEE Transaction on Information Forensics and Security, Vol. 14, Issue, 2019

2019-tifs-carving.pdf (8 MB)



In this study, we address the problem of forensic photo carving, which serves as one of the key sources of digital evidence in modern law enforcement. We propose efficient algorithms for assembling meaningful photographs from orphaned photo fragments, carved without access to file headers, meta-data or compression settings. The addressed problem raises a novel variant of a jigsaw puzzle with unknown number of mixed images, missing pieces, and severe brightness and colorization artifacts. We construct an efficient compatibility metric for matching puzzle pieces, and a corresponding image stitching procedure which allow to mitigate these artifacts. To facilitate photo assembly, we perform forensic analysis of the fragments to provide clues about their location within the frame of the imaging sensor. The proposed algorithm formulates the assembly problem as finding non-overlapping sets in an interval graph spanned over the input fragments. The algorithm exhibits lower computational complexity compared with a popular puzzle solving approach based on minimal spanning trees.


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