Hidden digital watermarks in images
US6700991B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 2000 |
| Grant date | Mar 2, 2004 |
| Priority date | — |
| Expiry date | Mar 7, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2201/0061
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An image authentication method by embedding digital watermarks into images, comprising: providing an original image and a watermark image; applying pseudo-random permutations to the watermark image for generating a dispersed watermark image; applying block-based permutations to the original image and the dispersed watermark image in order to form a plurality of original image blocks with each of the watermark blocks dispersed over the corresponding image block only; applying FDCT (Forward Discrete Cosine Transform) on each of the original image blocks independently so that each of the original image blocks is transformed into a DCT coefficient block that corresponds to different frequency ranges; embedding said watermark image blocks into said DCT coefficient blocks, in order to form a plurality of combined DCT coefficient blocks; applying IDCT (Inverse Discrete Cosine Transform) to the combined DCT coefficient blocks to form an embedded watermark image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.