Generic License Plate Detection via Multi-Region CNN Training

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Solution Overview

Problem

Existing license plate detection systems face challenges in complex scenarios such as shadows, noise, dust, partial overlap with other objects, low contrast, and varying license plate standards, leading to reduced accuracy, especially when operating on edge devices without GPU capabilities.

Innovation Solution

A system utilizing a Convolutional Neural Network (CNN) based approach for license plate detection, which includes a generic license plate detector module that can be trained with data from multiple countries, enabling detection across different regions with customized license plate standards, and operates efficiently on devices with limited CPU capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If computer vision-based techniques are used for license plate detection, then the system can operate in simple situations, but the accuracy is compromised in complex situations such as shadows, noise, dust, and partial overlap

Engineering Contradiction:
Improvedetection accuracyVSAvoidperformance in complex situations
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the license plate detection task into multiple specialized sub-models, each trained to handle specific complex situations (e.g., one model for shadows, another for dust, another for partial overlaps). This segmentation allows each model to specialize in particular challenging conditions, thereby improving overall detection accuracy across diverse complex scenarios while maintaining operational reliability.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If multiple specialized detectors are trained for different regions and license plate standards, then the detection accuracy improves, but the time to prepare ground-truth data increases

Engineering Contradiction:
Improvedetection accuracyVSAvoidground-truth preparation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements preliminary action by creating a generic license plate detector that is pre-trained on diverse multi-region data before being specialized into region-specific detectors. This preliminary training establishes a strong foundational model that accelerates the subsequent specialization process, reducing the ground-truth preparation time required for multiple specialized detectors while maintaining high detection accuracy across different regions and license plate standards.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If a generic license plate detector is trained with multi-region data, then the ground-truth preparation speed improves, but the model complexity increases

Engineering Contradiction:
Improveground-truth preparation speedVSAvoidmodel complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a generic license plate detector with multi-functionality that can handle multiple regions and license plate standards simultaneously. This universal model serves as a foundation that can be efficiently adapted to specific regions through transfer learning, thereby accelerating ground-truth preparation across multiple regions without proportionally increasing model complexity. The single generic model performs multiple detection functions that would otherwise require separate specialized models.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS11164028B2License plate detection system
Publication Date: 2021.11.02 NICE NORTH AMERICA LLC
  • US11164028B2 patent drawing
  • US11164028B2 patent drawing
  • US11164028B2 patent drawing

AI summary

A system for detecting license plates is described. The system receives raw data comprising images of license plates. A base version of a ground truth is prepared based on the raw data, using a generic license plate detection (LPD). The system prepares input data for training a deep learning network. The deep learning network is trained with the prepared input data. A newly trained generic (LPD) is formed using data generated by the existing generic (LPD).