Apparatus and method for recognizing the state of origin of a vehicle license plate
US8218822B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | May 14, 2008 |
| Grant date | Jul 10, 2012 |
| Priority date | — |
| Expiry date | Sep 21, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V20/625
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system analyzes various design characteristics of a vehicle license plate, including character size, placement and color, to identify the state of issuance of the plate. In some embodiments, the system uses spectral properties of light reflected from a vehicle license plate to determine spectral frequency bands having the best contrast between characters on the plate and the background of the plate. For example, red characters against a white background exhibit high contrast levels at wavelengths of about 420 nm to about 595 nm. Green characters against a white background exhibit high contrast levels at wavelengths of about 600 nm to about 750 nm. Blue characters against a white background exhibit high contrast levels at wavelengths of about 550 nm to about 750 nm. Thus, spectral characteristics in combination with other design-related characteristics of a license plate may be used to identify the state of origin of the plate. Once the state of origin is identified, origin-specific syntax matching may be used to enhance optical character recognition routines.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.