Efficient and fault tolerant license plate matching method
View Patent ↗A method and system for identifying a matching license plate. A pair of full or partial plate numbers to be matched can be received. The pair includes a target plate made up of a first set of characters and a suspect plate made up of a second set of characters. A set of number-order preserved sub-plates can be generated by adding and subtracting a single character from the second set of characters. Utilizing a site specific license plate matching table (P-table), a matching score between each of the sub-plates and the target plate may be calculated as part of a string correlation calculation. A maximum value for each of the sub-plate matching scores can then be calculated. The maximum value can be normalized to a 0˜100 scale and used as a final matching score. When the final matching score exceeds a predetermined threshold, an alert may be issued.
1. A method for identifying a matching license plate, said method comprising:
identifying a target plate comprising a first set of characters and a candidate plate comprising a second set of characters;
generating a set of sub-plates by adding or subtracting at least one character from the second set of characters;
computing a matching score between said candidate plate and said target plate;
computing a matching score between each of said sub-plates and said target plate; and
computing a maximum for each of said matching scores in order to thereafter normalize said maximum to obtain a final matching score for each of said matching scores.
2. The method of claim 1 further comprising issuing an alert if said final matching score exceeds a predetermined threshold.
3. The method of claim 1 further comprising calculating said matching score from a license-plate match table.
4. The method of claim 1 wherein a number order is preserved in each of said sub-plates.
5. The method of claim 1 further comprising computing said matching score utilizing a string convolution.
6. The method of claim 3 wherein said license-plate match table is specific to a site in which an image capture device is located.
7. The method of claim 6 wherein said license-plate match table is generated from heuristic rules regarding image similarity, site-specific mistakes in character recognition, and a plate simulation module.
8. A non-transitory computer-readable medium having computer-executable instructions for performing steps, said steps comprising:
identifying a target plate comprising a first set of characters and a candidate plate comprising a second set of characters;
generating a set of sub-plates by adding or subtracting at least one character from the second set of characters;
computing a matching score between said candidate plate and said target plate;
computing a matching score between each of said sub-plates and said target plate; and
computing a maximum for each of said matching scores in order to thereafter normalize said maximum to obtain a final matching score for each of said matching scores.
9. The non-transitory computer-readable medium of claim 8 wherein said steps further comprise issuing an alert if said final matching score exceeds a predetermined threshold.
10. The non-transitory computer-readable medium of claim 8 wherein said steps further comprise calculating said matching score from a license-plate match table.
11. The non-transitory computer-readable medium of claim 8 wherein a number order is preserved in each of said sub-plates.
12. The non-transitory computer-readable medium of claim 8 wherein said steps further comprise computing said matching score utilizing a string convolution.
13. The non-transitory computer-readable medium of claim 8 wherein said license-plate match table is specific to a site in which an image capture device is located.
14. The non-transitory computer-readable medium of claim 13 wherein said license-plate match table is generated from heuristic rules regarding at least one of image similarity, site-specific mistakes in character recognition, and a plate simulation module.
15. A system for identifying a matching license plate, said system comprising:
an image capture device;
a central processing unit operably connected to a database; and
a non-transitory computer-usable medium embodying computer code, said non-transitory computer-usable medium being coupled to said data bus, said computer program code comprising instructions executable by said processor and configured for:
identifying a target plate comprising a first set of characters and a candidate plate comprising a second set of characters;
generating a set of sub-plates by adding or subtracting at least one character from the second set of characters;
computing a matching score between said candidate plate and said target plate;
computing a matching score between each of said sub-plates and said target plate; and
computing a maximum for each of said matching scores in order to thereafter normalize said maximum to obtain a final matching score for each of said matching.
16. The system of claim 15 further comprising issuing an alert if said final matching score exceeds a predetermined threshold.
17. The system of claim 15 wherein said instructions are further configured for calculating said matching score from a license-plate match table.
18. The system of claim 15 wherein said instructions are further configured to preserve a number order in each of said sub-plates.
19. The system of claim 17 wherein said license-plate match table is specific to a site in which the image capture device is located.
20. The system of claim 19 wherein said license-plate match table is generated from heuristic rules regarding at least one of image similarity, site-specific mistakes in character recognition, and a plate simulation module.