Techniques for detecting, analyzing, and using visible authentication patterns
US7937588B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 2005 |
| Grant date | May 3, 2011 |
| Priority date | — |
| Expiry date | Sep 9, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/3284
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Improved techniques for making copy detection patterns and using them to detect copying relationships between digital representations. The techniques include techniques for including a message in a copy detection pattern without altering the copy detection patterns entropy and reading the message, techniques for using a copy detection pattern on an analog form to determine whether the analog form is an original analog form without reference to a digital representation of the original of the analog form's copy detection pattern, techniques for increasing the sensitivity of copy detection using copy detection patterns by modifying one of two copy detection patterns that are being compared to take into account alterations resulting from the copying process, techniques for distributing a copy detection pattern across a document, and techniques for using the entropy of a copy detection pattern to locate the copy detection pattern. Also disclosed are applications of copy detection patterns with copying that involves transformations between the digital and analog forms and with digital-to-digital copying.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.