Vehicle identification method and device

• US 20050179776A1
• Filed: 04/18/2005
• Published: 08/18/2005
• Est. Priority Date: 03/17/2003
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ikeda, Osamu, Nakashima, Hiroyuki, Hidaka, Shinji, Sasaki, Nobumasa, Natori, Hiroaki, Murakumo, Masashi, Amamoto, Tamotsu, Ikeda, Kunihiro, Maruta, Yutaka
• Granted Patent: US 7,302,085 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: G06V 20/625 License plates
• CPC Class Codes: G06V 20/63 Scene text, e.g. street names

Abstract

In order to improve an identification accuracy of a backlit number plate in a vehicle identification method and device which recognize a vehicle number from a number plate of a vehicle whose image is taken, an image frame of a vehicle is taken by an interlace method, irradiation is performed in an odd field and an even field composing the image frame with light of light quantities different from each other, images of the odd field and the even field are captured, and character recognition processing, only when character recognition processing of a number plate area extracted from an image of one field has ended in failure, of a number plate area extracted from an image of the other field is performed. Also, character recognition processings of number plate areas extracted from the images of the odd field and the even field respectively are performed in parallel, and a result of character recognition processing, only when character recognition processing of a number plate area extracted from an image of one field has ended in failure, of a number plate area extracted from an image of the other field, is adopted as an identification result of the vehicle.

Claims

1. A vehicle identification method comprising the steps of:

taking an image frame of a vehicle by an interlace method;

performing irradiation in an odd field and an even field composing the image frame with light of light quantities different from each other;

capturing images of the odd field and the even field; and

performing character recognition processing, only when character recognition processing of a number plate area extracted from an image of one field has ended in failure, of a number plate area extracted from an image of the other field.

3. The vehicle identification method as claimed in claim 1, wherein at the step of performing the irradiation, the light quantity of the irradiation for either the odd field or the even field is null.

4. The vehicle identification method as claimed in claim 1, wherein at the step of performing the irradiation, the irradiation is performed in the odd field and the even field not with the light of the light quantities different from each other but with light of a same light quantity, and at the step of capturing images, the images of the odd field and the even field are captured at shutter speeds different from each other.

2. A vehicle identification method comprising the steps of:

taking an image frame of a vehicle by an interlace method;

performing irradiation in an odd field and an even field composing the image frame with light of light quantities different from each other;

capturing images of the odd field and the even field;

performing character recognition processings of number plate areas extracted from the images of the odd field and the even field respectively in parallel; and

adopting a result of character recognition processing, only when character recognition processing of a number plate area extracted from an image of one field has ended in failure, of a number plate area extracted from an image of the other field, as an identification result of the vehicle.

5. A vehicle identification device comprising:

an image-taking portion for taking an image frame of a vehicle by an interlace method;

an irradiating portion for performing irradiation in an odd field and an even field composing the image frame with light of light quantities different from each other; and

an image processor for capturing images of the odd field and the even field and for performing character recognition processing, only when character recognition processing of a number plate area extracted from an image of one field has ended in failure, of a number plate area extracted from an image of the other field.

6. A vehicle identification device comprising:

an image-taking portion for taking an image frame of a vehicle by an interlace method;

an irradiating portion for performing irradiation in an odd field and an even field composing the image frame with light of light quantities different from each other; and

an image processor for capturing images of the odd field and the even field, for performing character recognition processings of number plate areas extracted from the images of the odd field and the even field respectively in parallel and for adopting a result of character recognition processing, only when character recognition processing of a number plate area extracted from an image of one field has ended in failure, of a number plate area extracted from an image of the other field, as an identification result of the vehicle.

7. The vehicle identification device as claimed in claim, wherein the irradiating portion makes the light quantity of the irradiation for either the odd field or the even field null.

8. The vehicle identification device as claimed in claim, wherein the irradiating portion performs the irradiation in the odd field and the even field not with the light of the light quantities different from each other but with light of a same light quantity, and the image processor captures the images of the odd field and the even field at shutter speeds different from each other.