【作者】 王春梅；

【导师】 吴晓娟；

【作者基本信息】 山东大学 ， 信号与信息处理， 2008， 硕士

【摘要】 签名是一种使用广泛的用于鉴定身份的生物特征,是社会生活普遍接受的一种同意或授权的方式。在电子商务银行业务、处理单据、签订合同等领域有广泛的应用,并具有相应的法律效力。但由于它的简单、易模仿性,也成为了伪造的目标,此时手写签名鉴定就会发挥它的作用。如果鉴定正确率高,将会对社会各行业包括行政、金融、处理法律纠纷、安全领域等方面能起到关键作用,因此在国家的经济建设中发挥重要作用。签名鉴定也是目前计算机模式识别领域的前沿课题。鉴于签名鉴定具有良好的应用前景和巨大的商业价值,世界各国许多学者和研究机构都对其表现出了极大兴趣。因此对签名技术的深入研究,对于提高实际应用水平和有关学科的科技进步具有着重要的意义。本文针对脱机手写签名鉴定的实玑,首先介绍了脱机手写签名鉴定的发展现状及国内外研究动态,探讨了脱机中文签名鉴定实现的主要方法。然后深入分析和研究了脱机签名鉴定中的预处理技术、特征提取技术和鉴定技术,并进行了相关的实验。在原始特征的提取时,为了尽可能体现签名的个体特征,同时提取了静态形状特征和伪动态特征。其中静态特征提取了几何特征和基于Zemike矩的形状特征;伪动态特征方面,我们提取了高灰度特征HPF、骨架方向灰度特征和灰度重心特征等。由于书写风格不同,每个人的签名都有自己的特点,对于随意的模仿,使用形状特征进行鉴定就可以达到较高的正确鉴定率,但对精心模仿的签名就很难鉴别出真伪。因此本文提出了一种将静态特征与伪动态特征相融合的脱机中文签名鉴定系统。因为压力,速度等动态特征很难模仿,即使表面上可以以假乱真的签名其灰度还是有很大差别的。这种采用静态特征与灰度特征相结合进行辨识的技术,可提高系统鉴别真伪的能力。另外,本论文尝试用2-阶鉴定的方法来提高鉴定的速度。这个二阶系统由两个独立的签名验证系统所构成。其中,第一阶段使用签名样本的几何特征和伪动态特征来鉴定签名的真伪,第二阶段则利用具有旋转不变的Zernike矩特征来鉴定签名的真伪。参考样本建立之后,当一个测试样本进入系统时,先以第一阶段的验证系统检查它。如果不符合我们的要求则可以直接判断该签名为伪签名,而不必进行下一阶段的鉴定;若通过第一阶段,则进入第二阶段,以Zernike矩特征来检查它的真伪。从实验中我们也证明了这一点是可行的,可以缩短简单伪造签名的鉴别时间,在不降低鉴定率的情况下我们提高了鉴定的速度。更多还原

【Abstract】 Signature is one of the most common biological features used for identity verification.Because of the significant advantages of signature identification as a way of personal identification such as:universality uniqueness stability and so on, it has a wide perspective applications in electronic-bank,military affairs, electronic-business,communication,office automation engineering files and so on. The research on this topic is not only important for practical applications but also the development of science.First,the application background,the development history and the researches at home and abroad of handwritten signature identification techniques are briefly introduced.The difficulties and main research methods of the off-line Chinese signature identification problem are analyzed.Then,the key techniques including image preprocessing,feature extraction and identification of off-line signature have been studied deeply in this thesis.The main researches include:The signatures,static shape feature and pseudo dynamic features have been extracted in feature extraction.The emphasis of shape feature is the pseudo-Zernike moment with rotation,scale and translation invariance and anti-noise character.The pseudo dynamic features high gray feature(HPF),framework aspect gray feature, and gray barycenter feature.In this thesis an off-line Chinese signature identification system based on pseudo feature and shape feature extraction is built furthermore,we adopted 2-pass identification method.As the writing styles are different,The signatures of different people vary from each other.The optional copy is easily identified using shape features.But it is difficult to find the intentional copies only using shape features. Imitating the writing press,peed and other dynamic features is difficult leads to superficially similar signatures have much difference.So we combine shape features with pseudo features to verify the using the feature fusion technique By this way we improve the ability of the signature identifications system. We try to improve the speed by using 2-pass verifying.The identification of 2-pass system is composed of two independent signature identification system.The first phase uses simple geometric features and pseudo-dynamic features to identify the authenticity of signatures,while the second phase uses Zernike moment to make a confirmation After the establishment of reference samples,when one pattern enters, the first phase of the inspection system to verify it.If it does not meet our requirements,we can judge it is false;if it have adopted the first phase,we use the second phase,Zernike moment to examine the characteristics.It has been proved that the identification of 2-pass system can save a lot of time for identification with out descending the correct identification rate.更多还原