Method for generating a digital record and roadside unit of a road toll system implementing the method

• US 10,255,804 B2
• Filed: 01/27/2016
• Issued: 04/09/2019
• Est. Priority Date: 03/20/2015
• Status: Active Grant

• Current Assignee: Kapsch TrafficCom AG (Datax Handelsgmbh)
• Original Assignee: Kapsch TrafficCom AG (Datax Handelsgmbh)
• Inventors: Gartner, Andreas, Nagy, Oliver, Ohreneder, Christian
• Primary Examiner(s): Gilliard, Delomia L
• Application Number:
  US15/559,766
• Publication Number:
  US 20180158327A1
• Time in Patent Office: 1,168 Days
• Field of Search: None
• CPC Class Codes: G06V 20/625 License plates
• CPC Class Codes: G06V 20/64 Three-dimensional objects
• CPC Class Codes: G07B 15/06 Arrangements for road pricing or congestion charging of vehicles or vehicle users, e.g. automatic toll systems
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors

Abstract

The present subject matter relates to a method and a roadside unit for generating a digital record of a vehicle in a road toll system, comprising: capturing an image of the vehicle on a roadway; data-compressing the image depending on at least one of a confidence level obtained from the image for one or more characters therein by means of OCR, and a contrast parameter obtained from the image or a region of interest therein or a section of the latter, to generate the digital record; and sending the digital record from the roadside unit to a data center of the road toll system.

Claims

1. A method for generating a digital record of a vehicle in a road toll system, comprising, in a roadside unit of the road toll system:

capturing an image of the vehicle on a roadway by means of a camera of the roadside unit;

data-compressing the image at a compression ratio depending on at least a confidence level obtained from the image for one or more characters therein by means of OCR to generate the digital record; and

sending the digital record from the roadside unit to a data center of the road toll system.

2. The method according to claim 1, wherein the image is data-compressed depending on the smallest of one or more confidence levels obtained by means of OCR.

3. The method according to claim 1, wherein in the step of data-compressing, the whole image is data-compressed at one and the same compression ratio.

4. The method according to claim 1, further comprising:

between said steps of capturing and data-compressing, finding, in the image, at least one region of interest containing said one or more characters and obtaining said one or more characters from said region of interest by means of OCR together with a confidence level of the OCR for each character, defining one or more sections in said region of interest, each section containing a character, and calculating a first compression ratio for each section depending at least on the confidence level of the character contained therein;

in said step of data-compressing, data-compressing the one or more sections, each at its first compression ratio to obtain one or more compressed sections, and data-compressing at least the remainder of the image at a predetermined second compression ratio to obtain a compressed image, wherein each first compression ratio is lower than said second compression ratio; and

in said step of sending, sending the compressed image together with the one or more compressed sections as the digital record from the roadside unit to the data center.

5. The method according to claim 4, wherein, in the digital record, the compressed image and the one or more compressed sections are merged.

6. The method according to claim 4, wherein the first compression ratio for at least one of the sections is determined also depending on at least the confidence level of a character contained in another section.

7. The method according to claim 4, wherein the region of interest covers, in the image, a license plate of the vehicle and an area which is separate from the license plate and contains one or more characters.

8. The method according to claim 6, wherein the first compression ratio for at least one of the sections of the license plate is determined also depending on at least the confidence level of a character contained in said other area.

9. The method according to claim 4, wherein the first compression ratio for each section is determined also depending on a contrast parameter of the image, of the region of interest, or of the respective section thereof.

10. The method according to claim 4, wherein, in the step of data-compressing, the complete image is data-compressed to obtain the compressed image.

11. The method according to claim 1, wherein the digital record further comprises the characters obtained by OCR.

12. The method according to claim 1, wherein the digital record further comprises the confidence level of at least one character.

13. The method according to claim 4, wherein the digital record further comprises the first compression ratio for each section.

18. The method according to claim 1, wherein the compression ratio further depends on a contrast parameter obtained from the image or a region of interest therein or a section of the region of interest.

19. The method according to claim 4, wherein the first compression ratio for at least one of the sections is determined also depending on the confidence levels of all characters in the region of interest.

14. A roadside unit for generating a digital record for a vehicle in a road toll system, comprising:

a roadside camera for capturing an image of the vehicle on a roadway;

a data-compression unit configured to data-compress the image at a compression ratio depending on at least a confidence level obtained from the image for one or more characters therein by means of OCR to generate the digital record; and

a transmitter connected to the data-compression unit and configured to send the digital record from the roadside unit to a data center of the road toll system.

15. The roadside unit according to claim 14, further comprising:

a selecting unit connected to the camera and configured to find, in the image, at least one region of interest containing one or more characters;

an OCR unit connected to the selecting unit and configured to obtain the one or more characters from the region of interest by means of OCR together with a confidence level of the OCR for each character;

a calculation unit connected to the OCR unit and configured to calculate a first compression ratio for each of one or more sections in said region of interest depending at least on the confidence level of the character contained in the respective section;

the data-compression unit being connected to the calculation unit, the selecting unit and the camera and configured to data-compress the one or more sections, each at its first compression ratio, to obtain one or more compressed sections, and to data-compress at least the remainder of the image at a predetermined second compression ratio to obtain a compressed image, wherein each first compression ratio is lower than said second compression ratio; and

the transmitter being configured to send, as the digital record, the compressed image together with the one or more compressed sections to the data center of the road toll system.

16. The roadside unit according to claim 15, wherein the selecting unit is configured to determine a contrast parameter of the image, the region of interest or a respective section thereof, and that the calculation unit is also connected to the selecting unit and is configured to calculate the first compression ratio for each section also depending on the contrast parameter.

17. The roadside unit according to claim 15, characterized in that the transmitter is also connected to the OCR unit and configured to include the characters obtained by OCR into the digital record for sending.

20. The roadside unit according to claim 14, wherein the compression ratio, which the data-compression unit is configured to data-compress the image at, further depends on a contrast parameter obtained from the image or a region of interest therein or a section of the region of interest.