License Plate Recognition via Intermediate Feature Verification

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Solution Overview

Problem

Conventional license plate number recognition systems have high error rates due to the accumulation of errors in multiple independent steps and strict requirements for input images, making them sensitive to weather and lighting conditions, and lacking verification mechanisms, resulting in the need for manual verification.

Innovation Solution

A license plate number recognition method using a pre-trained convolutional neural network that extracts features, includes verification features, and verifies the license plate number through intermediate convolution results, reducing errors by outputting results only when verification is passed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional multi-step independent processing is used for license plate recognition, then the recognition process can be implemented, but error rates accumulate across steps and reliability deteriorates

Engineering Contradiction:
Improverecognition accuracyVSAvoidprocessing steps
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple independent processing steps (image normalization, pre-processing, character segmentation, character recognition) into a unified deep learning model. The convolutional neural network performs feature extraction, segmentation, and recognition in an integrated manner, eliminating error accumulation between separate steps while maintaining comprehensive processing functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a verification mechanism that extracts intermediate convolution results during feature extraction and uses them to verify the final license plate recognition results. This feedback loop checks whether extracted features meet expected characteristics, allowing the system to identify and correct potential errors before final output, thereby improving reliability.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If strict requirements are imposed on input images regarding angles and definitions, then recognition precision can be maintained, but adaptability to various monitoring scenes deteriorates

Engineering Contradiction:
Improverecognition precisionVSAvoidscene adaptability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent employs a deep learning model that automatically adapts to varying image parameters including different angles, resolutions, lighting conditions, and weather scenarios. The convolutional neural network learns optimal feature representations across diverse parameter variations during training, enabling high recognition precision without imposing strict input requirements while maintaining broad scene adaptability.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If conventional recognition methods are used without verification mechanisms, then processing speed is maintained, but output error rate increases requiring manual verification

Engineering Contradiction:
Improveprocessing efficiencyVSAvoidoutput accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements a verification mechanism that extracts intermediate convolution results during feature extraction and uses them to verify the final license plate recognition results. This feedback loop checks whether extracted features meet expected characteristics, allowing the system to identify and correct potential errors before final output, thereby improving reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs verification checks on intermediate convolution results before final recognition output is generated. By conducting preliminary verification on extracted features against expected characteristics, the system prevents erroneous results from being output, reducing the need for manual verification while maintaining processing efficiency.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS11645857B2License plate number recognition method and device, electronic device and storage medium
Publication Date: 2023.05.09 SHENZHEN INTELLIFUSION TECHNOLOGIES CO LTD
  • US11645857B2 patent drawing
  • US11645857B2 patent drawing
  • US11645857B2 patent drawing

AI summary

A license plate number recognition method includes: extracting license plate number features of an image to be recognized including a license plate number, through a pre-trained convolutional neural network; extracting an intermediate convolution result during extracting the license plate number features, and extracting a first verification feature and/or a second verification feature according to the intermediate convolution result; verifying whether the license plate number features are correct according to the first and/or second verification features; if correct, outputting a predicted license plate number result according to the license plate number features. During the feature extraction process of the license plate number features, an intermediate feature is extracted as a verification feature to verify whether the extracted license plate number features are correct, and only when the verification is passed, outputting the license plate number result, which reduces the output error rate of the license plate number recognition result.