隨著電子化時代的來臨，人類的各種行為不可避免的將與資訊科技相結合。在此潮流之下，傳統的保密與認證方式如識別碼，已難以應付日益龐雜的電子交易與資訊保密措施等的需求。基於生物特徵難以複製或遭竊的特性，發展以個體在生物特徵上的辨識方法，將是補強這個缺口的最佳方法之一。 可供做個人身分確認的生物特徵有許多種，大致可分為兩類。一是行為上的特徵，例如：簽名、聲音，另一種則是生理學上的特徵，例如：掌紋、指紋、掌型、臉型、虹膜…等。隨著信用卡消費方式的普及，以個人簽名作為身分確認的方式亦廣為被大眾接受。本論文將以簽名辨識為對象，尤其將針對簽名時筆劃與筆劃間提筆的軌跡（虛筆）。以簽名的筆劃外型（實筆）作為辨識對象時，難以分辨出模仿技巧高超的仿冒簽名，但虛筆的軌跡對人眼來說幾乎是不可見的，更遑論模仿，卻可利用電子設備將虛筆軌跡紀錄下來。並以簽名的外形作為主要的辨識依據，將一維的簽名點資料轉換成二維的簽名影像，利用以離線簽名確認為主的技術做處理以及辨識。以此發展識別系統，將可杜絕相當程度的仿冒簽名。 The information technologies are now more and more blended into our daily life as the coming of electronic era. Traditional security ways, such as PIN code, are no longer reliable and difficult to satisfy the complex behaviors of e-commerce and information security. Unlike PIN code or passwords, biometrics can not be easily duplicated or stolen. Hence, they are more trustworthy and secure for identity verification. There are various kinds of biometrics that can be utilized for personal identification. With the popularity of credit cards, signature plays a very important role in authenticity and authorization. People are getting more familiar with the process of handwritten signature verification. Most of the researches on signature verification are based on the real-stroke, or the trajectories that users write on a digitizer surface. However, forgery signatures written by skilled imitators usually challenge the performance of real-stroke-based verification systems. In this thesis, both feature extraction and verification methods are focus on the virtual-strokes. The virtual-strokes are the trajectories between each real-stroke in a signature. They are hard to be seen by naked eyes, but can be recorded by electronic devices. Due to this special characteristic of virtual-strokes, most of the forgery signatures can be easily identified. After the signature data has been acquired, each set of the one-dimensional signature data is converted into a two-dimensional signature image. Then, off-line signature verification methods are employed to accomplish the signature verification task. The developed system can prevent the occurring of forgery signatures to certain extend.
