08218822 is referenced by 23 patents and cites 81 patents.

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.

Title
Apparatus and method for recognizing the state of origin of a vehicle license plate
Application Number
12/120375
Publication Number
8218822 (B2)
Application Date
May 14, 2008
Publication Date
July 10, 2012
Inventor
Alan K Sefton
Knoxville
TN, US
Agent
Luedeka Neely Group P C
Assignee
Pips Technology
TN, US
IPC
G06K 9/00
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