Watermark detection utilizing regions with higher probability of success
US6442284B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1999 |
| Grant date | Aug 27, 2002 |
| Priority date | — |
| Expiry date | Apr 30, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T1/0078
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The present invention detects the presence of a watermark in-an image by using a multi-step process. First, the image is examined to determine which regions of the image have characteristics such that there is a high probability that a watermark signal can be detected in that region of the image. Next the regions that have a high probability that a watermark can be detected (in contrast to all regions of the image) are examined to find watermark data. In order to determine the probability of finding watermark data in a particular region of an image, the amount of “variance” in the intensity of the pixels in the region is first examined. For example a region that is entirely white or entirely black has zero variance in luminance. Such a region can not carry watermark data, hence regions with zero or low variance can be eliminated from further processing. Furthermore, if a high variance in a region is a result of the fact that the region has an abrupt border or edge between two highly contrasting regions, the high variance does not indicate a high probability that a watermark signal will be detected in the region. Therefore, after regions with high variance are located, t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.