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