Method and apparatus for robust information coding
US5748783A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 8, 1995 |
| Grant date | May 5, 1998 |
| Priority date | — |
| Expiry date | May 8, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S283/901
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A digital signal is imperceptibly embedded into an input source signal, such as an image or video signal, to produce an encoded (sometimes termed "watermarked") signal. The principle of quasi-rotational symmetry is employed to facilitate detection of the embedded signal notwithstanding rotation of the encoded signal. Single or multiple degrees of symmetry can be employed. In another aspect, the digital signal is transformed to a frequency domain and phase-only filtered prior to its combination with the input source signal. In an illustrative embodiment, this filtering operation helps hide the digital signal within the source signal, and facilitates detection of the embedded digital signal even after the encoded signal has undergone various forms of corruption.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.