METHOD FOR AUTOMATIC LICENSE PLATE RECOGNITION USING ADAPTIVE FEATURE SET

• US 20120155712A1
• Filed: 12/17/2010
• Published: 06/21/2012
• Est. Priority Date: 12/17/2010
• Status: Active Grant

• Current Assignee: Conduent Business Services, LLC (Conduent, Inc.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Paul, Peter, Burry, Aaron Michael, Hannaway, William J., Fillion, Claude S.
• Granted Patent: US 8,447,112 B2
• Time in Patent Office: Days
• US Class Current: 382/105
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06V 20/625 License plates

Abstract

A method for determining a confidence level to be used in identifying a vehicle. The method includes receiving a vehicle image, extracting a license plate image from the at least one vehicle image, determining a license plate number and associated confidence level based upon the license plate image, and comparing the associated confidence level against a confidence threshold. If the associated confidence level is below the confidence threshold, the method further includes extracting auxiliary data from the at least one vehicle image, corresponding the extracted auxiliary data and a set of stored auxiliary data, and updating the associated confidence level to produce an updated confidence level based upon the correspondence of the extracted auxiliary data and the set of stored auxiliary data.

Claims

1. A method for determining a confidence level to be used in identifying a vehicle comprising:

receiving, by a processing device, at least one vehicle image;

determining, by the processing device, a license plate number and associated confidence level based upon the at least one vehicle image;

extracting, by the processing device, auxiliary data from the at least one vehicle image;

corresponding, by the processing device, the extracted auxiliary data and a set of stored auxiliary data; and

updating, by the processing device, the associated confidence level to produce an updated confidence level based upon the correspondence of the extracted auxiliary data and the set of stored auxiliary data.

2. The method of claim 1, wherein the determining a license plate number and associated confidence level further comprises performing an optical character recognition (OCR) identification algorithm on the at least one vehicle image.

3. The method of claim 2, wherein performing the OCR identification algorithm comprises:

extracting a license plate image from the vehicle image, wherein the license plate image comprises one or more characters;

segmenting each of the one or more characters in the license plate image; and

comparing each of the segmented characters against a set of standard character images.

4. The method of claim 1, wherein the auxiliary data comprises at least one of vehicle color, vehicle shape, vehicle design elements near the license plate, distinguishing marks, physical attributes, customized features, vehicle make, vehicle model, and model badges and emblems.

5. The method of claim 1, wherein the auxiliary data comprises at least one of time of day, day of the week, and location.

6. The method of claim 1, further comprising updating the set of stored auxiliary data upon updating the confidence level.

7. The method of claim 1, further comprising comparing the updated confidence level against a confidence threshold.

8. The method of claim 7, further comprising:

reporting the license plate number if the updated confidence level is higher than the confidence threshold; and

obtaining human interpretation if the updated confidence level is lower than the confidence threshold.

9. The method of claim 1, wherein the set of stored auxiliary data is stored on a processor readable storage medium operably connected to the processing device.

10. A method for determining a confidence level to be used in identifying a vehicle comprising:

receiving, by a processing device, at least one vehicle image;

extracting, by the processing device, a license plate image from the at least one vehicle image;

determining, by the processing device, a license plate number and associated confidence level based upon the license plate image;

extracting, by the processing device, auxiliary data from the at least one vehicle image;

corresponding, by the processing device, the extracted auxiliary data and a set of stored auxiliary data;

updating, by the processing device, the associated confidence level to produce an updated confidence level based upon the correspondence of the extracted auxiliary data and the set of stored auxiliary data; and

comparing, by the processing device, the updated confidence level against a confidence threshold.

11. The method of claim 10, wherein the determining a license plate number and associated confidence level further comprises performing an optical character recognition (OCR) identification algorithm on the license plate image.

12. The method of claim 11, wherein performing the OCR identification algorithm comprises:

identifying one or more characters in the license plate image;

segmenting each of the one or more characters in the license plate image; and

comparing each of the segmented characters against a set of standard character images.

13. The method of claim 10, wherein the auxiliary data comprises at least one of vehicle color, vehicle shape, vehicle design elements near the license plate, distinguishing marks, physical attributes, customized features, vehicle make, vehicle model, and model badges and emblems.

14. The method of claim 10, wherein the auxiliary data comprises at least one of time of day, day of the week, and location.

15. The method of claim 10, further comprising:

reporting the license plate number if the updated confidence level is higher than the confidence threshold; and

obtaining human interpretation if the updated confidence level is lower than the confidence threshold.

16. A method for determining a confidence level to be used in identifying a vehicle comprising:

receiving, by a processing device, a vehicle image;

extracting, by the processing device, a license plate image from the at least one vehicle image;

determining, by the processing device, a license plate number and associated confidence level based upon the license plate image;

comparing the associated confidence level against a confidence threshold; and

if the associated confidence level is below the confidence threshold;

extracting, by the processing device, auxiliary data from the at least one vehicle image,

corresponding, by the processing device, the extracted auxiliary data and a set of stored auxiliary data, and

updating, by the processing device, the associated confidence level to produce an updated confidence level based upon the correspondence of the extracted auxiliary data and the set of stored auxiliary data.

17. The method of claim 16, wherein the determining a license plate number and associated confidence level further comprises performing an object character recognition (OCR) identification algorithm on the license plate image.

18. The method of claim 17, wherein performing the OCR identification algorithm comprises:

identifying one or more characters in the license plate image;

segmenting each of the one or more characters in the license plate image; and

comparing each of the segmented characters against a set of standard character images.

19. The method of claim 16, further comprising:

reporting the license plate number if the updated confidence level is higher than the confidence threshold; and

obtaining human interpretation if the updated confidence level is lower than the confidence threshold.