Fragile watermarks for detecting tampering in images
US6064764A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 1998 |
| Grant date | May 16, 2000 |
| Priority date | — |
| Expiry date | Mar 30, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/3281
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A watermarking scheme for images which includes techniques for inserting and extracting fragile watermarks in the frequency domain and for determining whether an image so watermarked has been tampered with. Watermark insertion is accomplished by embedding the bits of a digital signature of a hash function of the image in the frequency coefficients of the image. Tamper detection is accomplished generally as follows: the fragile watermark which was embedded during the watermark insertion process is extracted from the image; the hash function of the image is computed as in the insertion process; it is verified using a public key whether the extracted watermark is a valid signature of the hash value. If so, then there is assurance that the image has not been tampered with. Otherwise, there is reason to conclude that the image has been tampered with.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.