Counteracting geometric distortions for DCT based watermarking
US6108434A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 12, 1997 |
| Grant date | Aug 22, 2000 |
| Priority date | — |
| Expiry date | Sep 12, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2201/0061
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Detection of a watermark in blocks of video or image data which has been subjected to affine geometric distortion is accomplished by approximating the distortion by a spatially varying translation of the blocks. The watermark is extracted by spatial translations of the blocks based on an assumed affine geometric distortion. The extracted watermarks are correlated with possible watermarks and the maximum correlator output is tested for statistical significance in order to determine whether a watermark is present in the image or video frame. The data may be compressed or uncompressed data. If the affine geometric distortion is known, a search for the maximum correlator output over a space of possible distortions can be performed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.