Automatic adjustment of image watermark strength based on computed image texture
US6222932A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 1997 |
| Grant date | Apr 24, 2001 |
| Priority date | — |
| Expiry date | Nov 26, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2201/0202
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system and method of automatically adjusts watermark strength of a watermarked image based on the content of the image. The described system includes a process by which the correct watermark strength is estimated with a model of preferred watermark strength based upon human perception as measured with a test group. Preferred watermark strength of a watermark within a watermarked reference image is determined and parameter constants associated with measured image texture values for the reference image are then determined. Image texture values are measured for a particular image to be watermarked, and these determined parameter constants are used to predict the strength of the watermark for the particular image. Images are watermarked by modifying the luminance of those pixels that fall within a mask specifying the watermark design. In this way, the chromaticity of the pixel remains constant but the luminance changes. The amount by which the luminance is changed is dependent on the desired strength of the watermark: a stronger watermark demands a larger change in the luminance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.