非接觸式指紋取像裝置與辨識系統

在現今的社會中，有許多不同種類的門禁，從傳統鎖匙到先進的生物特徵辨識，其目的皆為追求便利安全的門禁，所以本論文就針對生物特徵領域中的指紋辨識部分做相關研究。一般指紋取像裝置通常為指腹接觸式，因常會有沾污、故障等情況發生，所以必須經常委派專人做清潔維修的動作，為了避免此情況而影響到使用者操作，故本研究採取非接觸式指紋取像裝置(Touchless Fingerprint Sensor)。首先本研究會使用影像感測器(CMOS Sensor)與改良式短焦鏡頭(Lens)等裝置來擷取人類的指紋，在擷取的指紋影像中，可以明顯看到手指指腹的皮膚有高低起伏的紋路，且每個人的紋路都有差異，因此我們可以將此差異作為每個人的身份識別碼，以判定是何人；接著將取得的指紋運用影像分割(Image Segmentation)、指紋流向偵測(Ridge Direction)、影像增強、二值化處理等技術，將指紋紋路從背景分離出來，而後將單獨被分離的指紋做特徵擷取；依據不同的手指，會有不同的紋路特徵及其分岔位置，而不同的特徵組合，也就可以代表一個人的身份。在指紋特徵點(Minutiae)的比對部分，採取特徵點的角度、距離、方向作為依據，運用旋轉比對的技術，針對旋轉的指紋作處理。在指紋辨識系統的可攜式方面，採用目前最常見的嵌入式系統，並搭配FPGA來完成硬體實作。本研究測試所使用的指紋資料庫有(1)Touchless Fingerprint Sensor所即時擷取的指紋影像；(2) FVC2002主辦單位提供的指紋測試資料庫；(3)Biometric System Lab.實驗用的各類指紋影像；經由實驗的結果，指紋辨識系統可以達到的辨識率從71.43%到92.86%。在辨識的準確度方面，因某些指紋影像有清晰度的問題，所以影響到系統的辨識率。故我們可以運用非接觸式指紋取像裝置，來避免污損等情況所影響的辨識率。

關鍵字

指紋辨識；特徵比對；門禁；影像增強；指紋流向；影像感測器

並列摘要

Nowadays, there are many kinds of Entrance Guard System. From old simple key to advanced biometrics identification technologies, their main purposes are to provide convenience and security. This paper aims at fingerprint recognition biometrics technology. The traditional Fingerprint Recognition System is usually contact-type. The drawback of contact-type is that it is easy to make dirty, so we have to maintain and clean it often. We apply Touchless Fingerprint Sensor in order to avoid this kind of situation. First, we use CMOS Sensor with improved Short Focus Lens to get fingerprints. Because the fingerprint of each human being is unique, we can exploit this unique characteristic to do identification and to know who owns this fingerprint. Then, Scanned the fingerprint image is processed by various technologies such as Image Segmentation, Ridge Direction, Image Enhancement, and Binarization to produce a lot of information we need. Afterwards, we can utilize this information for identification. To compare Minutia, we focus on the angle, distance, and direction of Minutiae. We use the rotation technology to process rotated fingerprints. To develop small-sized Fingerprint Recognition System, we use the FPGA-based embedded system to implement this system. The FPGA is used to accelerate the fingerprint to identification algorithm. The fingerprint databases in this paper are from three sources. First is taken from Touchless Fingerprint Sensor that is instant fingerprint image. Second is an FVC2002 sponsor offer the testing database. Third source is Biometric System Lab. experimental image. Experiments show that our Touchless Fingerprint Recognition System can reach recognition rate from 71.43% to 92.86%. On the precision of recognition, some images had the problem of clarity, influencing the system recognition rate. Thus we used Touchless Fingerprint Sensor to avoid possibility that the dust could affect the recognition rate.

並列關鍵字

Fingerprint Recognition ； Minutiae Matching ； Entrance Guard System ； Image Enhancement ； Ridge Direction ； CMOS Sensor

參考文獻

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非接觸式指紋取像裝置與辨識系統

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