Our paper, “Camcording-resistant Forensic Watermarking Fallback System using Secondary Watermark Signal,” was accepted for publication in IEEE Transactions on Circuits and Systems for Video Technology (TCSVT). Public full-text on ResearchGate.
To protect movies from digital piracy, forensic watermarking is used to track down pirates when they illegally leak copyright-protected videos. That is, each legitimate user gets a unique version of the video that contains a hidden watermark. If a pirate leaks his or her watermarked version, he or she is identified by the watermark.
Unfortunately, forensic watermarking does not always work in practice. Smart pirates can delete the watermark before leaking the video (even though this is not always easy). In that case, existing watermarking techniques fail: the “primary” watermark cannot be detected anymore.
Although the primary watermark is deleted, our proposed fallback system can still detect a “secondary” watermark. As such, we can still trace these smart pirates!
The secondary watermark is automatically created by a video encoder that compresses the video. During compression, the video encoder reduces the file size at the cost of slightly reducing the quality: they create (imperceptible) compression artifacts. What is most important for this paper, is that the primary watermark has an influence on the compression artifacts. A different primary watermark results in different compression artifacts. As such, the compression artifacts are the secondary watermark.
Most importantly, the secondary watermark survives (targeted) attacks better than the primary watermark. For example, in the experiments, it increased the robustness against recompression attacks, camcording attacks, and attacks targeted towards the specific watermarking methods.
In conclusion, the fallback system can be used when existing techniques fail. Even when all primary watermarking information is deleted, the secondary watermark can still be detected!
This work was done in collaboration with the Imaging research group at UNSW Canberra.
Also read / watch: Traitor Tracing After Visible Watermark Removal