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Universitas Hasanuddin
Research output:Contribution to journalArticlepeer-review

Improvement of Vehicle License Plate Detection and Recognition with the Addition of the CLAHE Method

Zulkarnain E.

Beyond Technology Summit on Informatics International Conference Bts I2c 2025

Published: 2025

Abstract

Automatic License Plate Recognition (ALPR) detection and recognition play an important role in modern traffic monitoring systems, especially in the implementation of Electronic Traffic Law Enforcement (ETLE). The main challenge of this system is the low image quality owing to uneven lighting and vehicle movement. This study proposes to improve the performance of the YOLOv11 model by adding a preprocessing stage using Contrast Limited Adaptive Histogram Equalization (CLAHE) and Unsharp Masking to improve contrast and image sharpness. The dataset was taken from ETLE CCTV footage on Jalan A.P. Pettarani, Makassar, under low-light conditions. The test results showed that the combination of CLAHE and Unsharp Masking gave the best performance with a Precision of 0.946, Recall of 0.977, mAP50 of 0.978, and mAP50–95 of 0.833. The evaluation of character recognition using EasyOCR also showed the lowest Character Error Rate (CER) value of 6.35%. Thus, this combined method has been shown to be effective in improving the detection and recognition accuracy of license plates and has the potential to be implemented in ETLE systems under real traffic conditions.

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Adaptive histogram equalizationSciences
Artificial intelligenceSciences
Computer scienceSciences
Computer visionSciences
LicenseSciences
PreprocessorSciences
Contrast (vision)Sciences
HistogramSciences
Unsharp maskingSciences
Noise (video)Sciences
Pattern recognition (psychology)Sciences
Traffic signSciences
Template matchingSciences
Image qualitySciences
Masking (illustration)Sciences
AlphanumericSciences
Histogram equalizationSciences
Character recognitionSciences
LegibilitySciences
EngineeringSciences
Matching (statistics)Sciences
Precision and recallSciences
Normalization (sociology)Sciences