Determination of a best offset to detect an embedded pattern
US6330673A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 14, 1998 |
| Grant date | Dec 11, 2001 |
| Priority date | — |
| Expiry date | Oct 14, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L19/018
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Watermark data is encoded in a digitized signal by forming a noise threshold spectrum which represents a maximum amount of imperceptible noise, spread-spectrum chipping the noise threshold spectrum with a relatively endless stream of pseudo-random bits to form a basis signal, dividing the basis signal into segments, and filtering the segments to smooth segment boundaries. The data encoded in the watermark signal is precoded to make the watermark data inversion robust and is convolutional encoded to further increase the likelihood that the watermark data will subsequently be retrievable notwithstanding lossy processing of the watermarked signal. A watermark alignment module determines which of a large number of offsets of the watermarked data is most likely to correspond to a recognizable watermark. The watermark alignment module uses a single basis signal to evaluate a number of offsets over a relatively narrow range of offsets. In addition, offsets which differ by an integer multiple of a spatial/temporal granularity of respective noise threshold spectra are recognized as corresponding to equivalent noise threshold spectra. Accordingly, a previously generated noise threshold spect…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.