METHOD AND SYSTEM FOR ROBUST TILT ADJUSTMENT AND CROPPING OF LICENSE PLATE IMAGES
First Claim
1. A method for tilt adjustment and cropping of license plate images, the method comprising:
- converting an image of a vehicle into a binary image, said image of said vehicle including data indicative of a license plate of said vehicle and license plate characters thereof;
removing a long run within a binary image and applying a morphological filtering to break an unwanted connection between said license plate characters due to a license plate frame and an image noise;
identifying and screening a connected component within said binary image based on a plurality of key metrics to remove all but the most likely candidate character connected components from said binary image; and
performing a line-fit based iterative search for a tilt removal and a vertical cropping of said binary image to obtain a tight bounding box with respect to said license plate characters if a sufficient candidate character remains after performing said line-fit based iterative search, thereby removing any inherent tilt and obtaining a vertically cropped license plate image based on said image of said vehicle.
1 Assignment
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Accused Products
Abstract
Methods, systems and processor-readable media for robust tilt adjustment and cropping of a license plate image. A vehicle image can be captured by an image-capturing unit and converted to a binary image utilizing a binarization approach. A long run within the binary image can then be removed and a morphological filtering can be applied to break an unwanted connection between characters due to a license plate frame and an image noise. A connected component (CC) within the image can be identified and screened based on a number of key metrics to remove a most likely candidate character connected component. A line-fit based iterative search process can then be performed for robust tilt removal and vertical cropping of the license plate image to obtain a tight bounding box on the license plate characters if sufficient candidate characters remain after the search process. Otherwise, the region of interest can be rejected.
51 Citations
20 Claims
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1. A method for tilt adjustment and cropping of license plate images, the method comprising:
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converting an image of a vehicle into a binary image, said image of said vehicle including data indicative of a license plate of said vehicle and license plate characters thereof; removing a long run within a binary image and applying a morphological filtering to break an unwanted connection between said license plate characters due to a license plate frame and an image noise; identifying and screening a connected component within said binary image based on a plurality of key metrics to remove all but the most likely candidate character connected components from said binary image; and performing a line-fit based iterative search for a tilt removal and a vertical cropping of said binary image to obtain a tight bounding box with respect to said license plate characters if a sufficient candidate character remains after performing said line-fit based iterative search, thereby removing any inherent tilt and obtaining a vertically cropped license plate image based on said image of said vehicle. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for tilt adjustment and cropping of license plate images, said system comprising:
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a processor; a data bus coupled to said processor; and a computer-usable medium embodying computer program code, said computer-usable medium being coupled to said data bus, said computer program code comprising instructions executable by said processor and configured for; converting an image of a vehicle into a binary image, said image of said vehicle including data indicative of a license plate of said vehicle and license plate characters thereof; removing a long run within a binary image and applying a morphological filtering to break an unwanted connection between said license plate characters due to a license plate frame and an image noise; identifying and screening a connected component within said binary image based on a plurality of key metrics to remove all but the most likely candidate character connected components from said binary image; and performing a line-fit based iterative search for a tilt removal and a vertical cropping of said binary image to obtain a tight bounding box with respect to said license plate characters if a sufficient candidate character remains after performing said line-fit based iterative search, thereby removing any inherent tilt and obtaining a vertically cropped license plate image based on said image of said vehicle. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A processor-readable medium storing code representing instructions to cause a process to perform a process for tilt adjustment and cropping of license plate images, said code comprising code to:
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convert an image of a vehicle into a binary image, said image of said vehicle including data indicative of a license plate of said vehicle and license plate characters thereof; remove a long run within a binary image and apply a morphological filtering to break an unwanted connection between said license plate characters due to a license plate frame and an image noise; identify and screen a connected component within said binary image based on a plurality of key metrics to remove all but the most likely candidate character connected components from said binary image; and perform a line-fit based iterative search for a tilt removal and a vertical cropping of said binary image to obtain a tight bounding box with respect to said license plate characters if a sufficient candidate character remains after performing said line-fit based iterative search, thereby removing any inherent tilt and obtaining a vertically cropped license plate image based on said image of said vehicle. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification