Edge-Based Sliding Windows for License Plate Detection
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Solution Overview
Problem
Conventional registration plate detection methods are either too fast and inaccurate due to ambient light variations or too slow due to complex calculations, making them unsuitable for practical applications like parking lot management.
Innovation Solution
A method and apparatus for registration plate detection that involves image processing to generate edge images through gradient calculations and iterative edge threshold estimation, using selective filters to quickly and accurately detect registration plates, suitable for applications like parking lot management, surveillance, and self-driving systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional registration plate detection methods are used to rapidly perform detection, then detection speed is improved, but detection accuracy deteriorates due to ambient light variations
Solution Approach 1:
The patent applies preliminary action by performing edge detection and threshold estimation before the actual registration plate detection. The edge image is generated in advance through gradient calculation and edge threshold estimation, preparing the image data in a transformed domain that is more robust to ambient light variations, thereby enabling both fast and accurate detection.
Solution Approach 2:
The patent uses an intermediary approach by introducing an edge image as a mediator between the original image and the detection process. The edge image, generated through gradient calculation and threshold estimation, serves as an intermediate representation that captures structural information while being less sensitive to lighting conditions, thus resolving the contradiction between speed and accuracy.
2Measurement precision
If conventional registration plate detection methods use complicated calculations to improve accuracy, then detection accuracy is improved, but detection speed deteriorates to extremely slow processing
Solution Approach 1:
The patent applies segmentation by dividing the image processing into distinct functional stages: gradient calculation, edge threshold estimation, edge image generation, and finally registration plate detection. Each stage processes specific aspects of the image data independently, allowing optimized processing at each step without requiring all calculations to be performed simultaneously, thus improving overall speed while maintaining accuracy.
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the edge threshold through iterative calculation based on gradient data. This adaptive thresholding allows the system to optimize detection parameters for each specific image without requiring complex manual tuning or extensive pre-processing, achieving both high accuracy and fast processing speeds.
Data Source
AI summary
A method for performing registration plate detection includes: performing image processing on image data of a predetermined region in an image to generate an edge image; and performing registration plate detection according to the edge image and the image data of the predetermined region to determine a location of a registration plate image within the predetermined region, for performing a post-processing corresponding to the registration plate image. The step of performing the image processing includes: performing gradient calculations on image data of the predetermined region to generate a gradient image, where the gradient image includes gradient data of the predetermined region; performing edge threshold estimation on the gradient data of the predetermined region, to update an edge threshold through a set of iterative calculations; and generating the edge image according to the edge threshold and according to selective gradient data of the predetermined region.