Method of embedding digital watermark, storage medium in which the method is stored, method of identifying embedded digital watermark, and apparatus for embedding digital watermark
US6983058B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 8, 1999 |
| Grant date | Jan 3, 2006 |
| Priority date | — |
| Expiry date | Sep 8, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2201/0063
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The procedure of the present invention specifies predetermined elements included in a matrix F which is obtained by Fourier transform of master image data P0 (step S122), and adds a minute variation ΔF of a predetermined magnitude to either a real number array FR or an imaginary number array FI of the predetermined elements (step S124 and S126). Here note that the minute variation ΔF should be subtracted from corresponding elements, in order to keep the symmetry of the Fourier spectrum. A resulting image obtained by an inverse transform of the matrix with the minute variation ΔF added thereto includes a phase difference pattern W01 that is embedded therein and corresponds to the minute variation ΔF. As long as a master image is closed to the public, this embedded pattern can not be taken out of the resulting image nor be deleted by overwriting attacks. Even if the processed data with the digital watermark embedded therein is exposed to overwriting attacks of different pieces of watermark information by the similar algorithm, the arrangement of the information enables the digital watermark embedded in the master data to be taken out accurately. The similar series of processing may b…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.