Watermark embedder and reader
AssigneeDigimarc Corporation
InventorsGeoffrey B. Rhoads, Ammon E. Gustafson
Life of this patent
Estimating the term…
Abstract
A watermark system includes an embedder, detector, and reader. The watermark embedder encodes a watermark signal in a host signal to create a combined signal. The detector looks for the watermark signal in a potentially corrupted version of the combined signal, and computes its orientation. Finally, a reader extracts a message in the watermark signal from the combined signal using the orientation to approximate the original state of the combined signal. While adapted for images, video and audio, the watermark system applies to other electronic and physical media. For example, it can be applied to mark graphical models, blank paper, film and other substrates, texturing objects for ID purposes, etc.
Claims18
A method of detecting a watermark in a multidimensional signal, the method comprising:
- estimating an initial orientation of a watermark signal in the multidimensional signal without reference to an original, un-watermarked version of the multidimensional signal;
- and
- refining the initial orientation to compute a refined orientation, including computing at least one orientation parameter that:
- increases correlation between the watermark signal or watermark signal attribute and the multidimensional signal, or
- improves recovery of known watermark message bits from the watermark signal, when the watermark or multidimensional signal are adjusted with the refined orientation.
A method of detecting a watermark in a target signal, the method comprising:
- computing orientation parameter candidates of a watermark signal in different portions of the target signal;
- comparing similarity of orientation parameter candidates from the different portions of the target signal;
- based at least in part on comparing the similarity of the orientation parameter candidates, determining an orientation of the watermark in the target signal.
A method of detecting a watermark in a target signal:
- estimating orientation of the watermark in the target signal;
- using the orientation to extract a measure of the watermark in the target;
- and
- using the measure to assess merits of the estimated orientation.
A watermark detector comprising:
- means for computing orientation of a watermark signal in a target signal without reference to an original, un-watermarked version of the target signal;
- means for adjusting at least portions of the target signal based on the orientation;
- and
- means for reading a message encoded in the watermark signal from the adjusted target signal portions.
Dependencies are inferred from the claim text.