Multi-bit watermarking robust to Stirmark
- When?
- Monday 22 November 2010, 13:30 to 14:30
- Where?
- 39BB02 - all welcome
- Open to:
- Staff, Students
- Speaker:
- Dr Steve Wesemeyer
Substantial interest in digital watermarking over the last 15 years resulted in a considerable number of different watermarking systems that have been proposed. However, despite this extensive literature on watermarking, not much progress has been made in tackling one of the most devastating attacks on these systems:
the original Stirmark attack introduced by Peticolas et al.
The attack has been described as the software equivalent of a high resolution print-scan attack which is part of a much larger class of random bending attacks (RBAs).
We introduce a novel robust, multi-bit, blind watermarking system which is robust against the (in)famous Stirmark local random bending attack (as well as a number of other common attacks). It uses a property of distortion compensated quantization index modulation~(DC-QIM) which allows the embedder to vary the embedding strength while the detector only needs to know the quantization step size This is coupled with a simple heuristic human-vision system~(HVS) measure that quantifies how smooth or textured the area around a pixel is Finally, the detector uses a soft-decision metric to associate probabilities with each extracted bit of the attacked watermark enabling the use of soft-decision error correction codes.
