Alternating Camera Parameters for License Plate and Vehicle Detection
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Solution Overview
Problem
Existing imaging systems struggle to simultaneously capture clear images of both license plates and entire vehicles using a single camera, due to the significant difference in specular and diffuse reflectivity properties between these objects, leading to underexposure or overexposure issues.
Innovation Solution
The system employs alternating camera parameters such as integration times, illumination pulse widths, and camera gain between subsequent video frames to optimize image capture for both retroreflective (license plates) and non-retroreflective (vehicles) objects, allowing for the capture of resolvable license plate images and properly exposed vehicle images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera uses fixed imaging parameters, then the structure is simple and operation is easy, but it cannot simultaneously capture both retroreflective (license plates) and non-retroreflective (vehicles) objects with proper exposure
Solution Approach 1:
The patent applies dynamics by making the camera parameters changeable over time. The system alternates between first imaging parameters (optimized for retroreflective objects like license plates) and second imaging parameters (optimized for non-retroreflective objects like vehicles) between sequential video frames. This dynamic parameter switching enables a single camera to capture both object types with proper exposure, resolving the contradiction between simple device structure and high measurement precision.
2Measurement precision
If separate cameras are used for license plates and vehicles, then image quality for both objects is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by enabling a single camera to perform multiple functions: capturing images of both retroreflective objects (license plates) and non-retroreflective objects (vehicles) with appropriate exposure. By implementing alternating imaging parameters between sequential frames, the camera becomes a multi-functional device that replaces what would traditionally require two separate cameras, thus reducing device complexity and cost while maintaining high measurement precision for both object types.
3Measurement precision
If imaging parameters are optimized for retroreflective objects, then license plate detection is improved, but non-retroreflective objects become underexposed
Solution Approach 1:
The patent applies periodic action by alternating between different imaging parameters in sequential video frames. In odd frames, the camera uses first imaging parameters optimized for retroreflective objects (license plates), and in even frames, it uses second imaging parameters optimized for non-retroreflective objects (vehicles). This periodic switching ensures that each object type receives appropriate exposure in its designated frames, resolving the contradiction between license plate detection quality and vehicle image exposure.
4Measurement precision
If imaging parameters are optimized for non-retroreflective objects, then vehicle detection is improved, but retroreflective objects become overexposed
Solution Approach 1:
The patent applies periodic action by alternating between different imaging parameters in sequential video frames. In odd frames, the camera uses first imaging parameters optimized for retroreflective objects, and in even frames, it uses second imaging parameters optimized for non-retroreflective objects. This periodic switching ensures that each object type receives appropriate exposure in its designated frames, resolving the contradiction between vehicle detection quality and license plate image exposure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the simultaneous detection and identification of license plates and vehicle features using a single camera, achieving cost savings by reducing the number of cameras required for traffic monitoring and surveillance applications.
Implementation Method 1
defining first and second camera parameters, respectively optimized for detecting a retroreflective and a non-retroreflective object
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2D
AI summary
First and second camera parameters are optimized (502) for detecting a respective retroreflective and non-retroreflective object. A sequential series of first and second video frames are captured (504) based on the first and second camera parameters, and the retroreflective and non-retroreflective object are detected (508) in a camera scene based on the respective first and second video frames of the series.