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Ingemar J. Cox (NEC Research Institute):
"Applying Informed Coding and Embedding to Design a Robust, High Capacity Watermark"

Tuesday, June 11, 2002, 4:00 PM EST (refreshments); 4:30 PM (lecture)

high bandwidth (320x240) || low bandwidth (160x120)

Bartos Theatre, MIT Media Lab (E15)

Electronic Publishing group

We describe a new watermarking system based on the principles of informed coding and informed embedding. This system is capable of embedding 1380 bits of information in images with dimensions of 240 x 368 pixels. Experiments on 2000 images indicate the watermarks are robust to significant valumetric distortions, including additive noise, low pass filtering, changes in contrast, and lossy compression.

Our system encodes watermark messages with a modified trellis code in which a given message may be represented by a variety of different signals, with the embedded signal selected according to the cover image. The signal is embedded by an iterative method that seeks to ensure the message will not be confused with other messages, even after addition of noise. Fidelity is improved by the incorporation of perceptual shaping into the embedding process. We show that each of these three components improves performance substantially.

Ingemar J. Cox holds a BSc from University College London and a PhD from Oxford University. He worked at AT&T Bell Labs from 1984 until 1989, and in 1989 joined the NEC Research Institute as a senior research scientist. From 1997 to 1999, he served as CTO of Signafy, an NEC subsidiary responsible for commercialization of watermarking. In 1999, he returned to the NEC Research Institute as a research fellow.

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