摘要 |
Directional albedo of a particular article, such as an identity card, is measured and stored. When the article is later presented, it can be confirmed to be the same particular article by re-measuring the albedo function, and checking for correspondence against the earlier-stored data. The re-measuring can be performed through us of a handheld optical device, such as a camera-equipped cell phone. The albedo function can serve as random key data in a variety of cryptographic applications. The function can be changed during the life of the article. A variety of other features are also detailed. |
申请人 |
DIGIMARC CORPORATION;RHOADS, GEOFFREY, B.;RODRIGUEZ, TONY, F;BRADLEY, BRETT, A. |
发明人 |
RHOADS, GEOFFREY, B.;RODRIGUEZ, TONY, F;BRADLEY, BRETT, A. |