車牌辨識系統的實作

Implementation of License Plate Recognition System

呂建德(Chien-Te Lu)

指導教授 ： 王永鐘

國立臺北科技大學/電資學院/電機工程系所/碩士(2009年)

摘要

本論文著重於將車牌辨識運用於室內停車場系統中，為了讓車主使用此系統時避免等待時間過久，提出快速車牌辨識的方法。車牌辨識步驟中車牌定位和字元切割最耗時間，因此本文提出快速車牌定位和字元切割方法。先將車牌影像縮小灰階化減少運算量，用底帽轉換的加強低頻影像，以找出可疑車牌位置，運用區域平均二值化將車牌字元和車牌背景分離。字元切割部分，利用垂直投影法將字元切割，切割後的影像使用字元特徵方式辨識。
為驗證系統的可行性，本論文將所提出快速車牌定位和字元切割方法實作於本校停車場的管理系統，實驗結果發現車牌辨識的處理時間低於500ms的商用車牌辨識系統規範，且辨識成功率維持90%。

關鍵字

車牌辨識 ； 車牌定位 ； 影像處理 ； 停車場系統

並列摘要

The purpose of this thesis is to explain how the indoor parking system uses the license plate recognition to shorten the user's waiting time. License plate locating and segmentation of the plate characters are quite time consuming in license plate recognition. So this thesis presents high-speed License plate locating and segmentation of the plate characters methods. First, decrease and gray the license plate image which will decrease the operational volume. Then use Bottom hat transform to indicate the bottom value of the original image and locate the license plate. Use local average threshold to separate the license plate characters and license plate back ground. In the segmentation of the plate characters use vertical projection method to divide characters, then use character features to recognize each character.
In order to verify the system feasibility. This thesis presents high-speed License plate locating and segmentation of the plate characters methods and implements the system at the NTUT underground parking system. The experimental results measuring up to less than the 500ms complete the license plate recognition norms of business, and the percentage of literacy rate is 90%.

並列關鍵字

License plate recognition ； License plate location ； Image processing ； Parking system

參考文獻

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