Document alteration indicating system and method
US6748102B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 24, 2001 |
| Grant date | Jun 8, 2004 |
| Priority date | — |
| Expiry date | Dec 12, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07D7/20
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A system and method for detecting alteration of a document. The invention evaluates markings in half-tone fields by ascertaining a first dot count of dots isolated from the marking in the half-tone field of the document; forming an image of the marking; superimposing the image on a blank half-tone field having the same predetermined pattern as the half-tone field of the document; ascertaining a second dot count of dots isolated from the image superimposed on the blank half-tone field; and determining whether the marking has been altered by comparing the first dot count to the second dot count. An alteration is indicated where the first dot count and second clot count are different.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.