论签名笔迹的频谱分析方法

通过一种签名笔迹的频谱分析方法,并提取签名笔迹的压力、速度等动态特征数据,利用傅立叶变换原理,对特征数据进行频谱分析。实验研究发现,同一人的签名笔迹频谱图相似度高,且明显区别于他人的签名笔迹。签名笔迹的频谱分析方法可以直观、有效的鉴别签名笔迹。     

签名笔迹动态特征的理论研究

本文以签名笔迹为研究对象,提取书写过程中的动态特征,在此基础上,对签名笔迹动态特征的概念和属性进行了深入的探讨,构建了一套较为完整的签名笔迹动态特征的理论系统。     

中文签名笔迹动态特征研究

从物理学角度看,笔迹是书写工具在力的作用下在载体上形成的运动轨迹.作用力和速度的大小和变化构成了书写运动的动态特征.本文以签名笔迹为对象,研究签名笔迹的动态特征及其属性.实验结果表明动态特征能够作为认定书写人,鉴别摹仿签名的重要依据.     

中文签名笔迹动态特征研究

从物理学角度看,笔迹是书写工具在力的作用下在载体上形成的运动轨迹。作用力和速度的大小和变化构成了书写运动的动态特征。本文以签名笔迹为对象,研究签名笔迹的动态特征及其属性。实验结果表明：动态特征能够作为认定书写人,鉴别摹仿签名的重要依据。     

中文签名笔迹动态特征研究

从物理学角度看,笔迹是书写工具在力的作用下在载体上形成的运动轨迹.作用力和速度的大小和变化构成了书写运动的动态特征.本文以签名笔迹为对象,研究签名笔迹的动态特征及其属性.实验结果表明:动态特征能够作为认定书写人,鉴别摹仿签名的重要依据.     

中文签名笔迹动态特征研究

从物理学角度看,笔迹是书写工具在力的作用下在载体上形成的运动轨迹.作用力和速度的大小和变化构成了书写运动的动态特征.本文以签名笔迹为对象,研究签名笔迹的动态特征及其属性.实验结果表明:动态特征能够作为认定书写人,鉴别摹仿签名的重要依据.     

再看摹仿签名笔迹鉴定

由于签名笔迹字数少、可摹仿性强的特点,长期以来,摹仿签名笔迹鉴定始终是笔迹鉴定的难点。笔者从不同类型的摹仿方法出发,讨论不同方法下摹仿签名笔迹的特点,总结其特征规律。同时要重视笔迹鉴定过程中了解相关案情,为识别是否存在摹仿现象提供线索。在此基础之上,对比摹仿签名笔迹特征的变化规律,并从摹仿签名笔迹特征反映构成方面系统性地进行鉴定,鉴别是否存在摹仿签名的情况。通过撰写此文,以期对摹仿签名笔迹鉴定实务具有借鉴意义。     

浅谈对签名笔迹的检验

1 签名笔迹的特点 签名笔迹与其它笔迹相比较,有其独自的特点:1.签名笔迹的案由都是涉及到经济问题;2.签名笔迹字数少(两、三个字);3.签名笔迹的相同字、同名部首及同名笔画少;4.签名笔迹重复出现的笔迹特征少;5.签名笔迹可比性强的特征少。 2 对签名笔迹检验的方法 对签名笔迹检验的方法,是遵循同一认定的基本原理,对送检文字材料的笔迹特征同嫌疑人     

设计签名的特点和鉴定方法

设计签名作为特殊的签名种类有其特有的书写规范和特征．在设计签名笔迹鉴定中既要遵循一般的笔迹检验技术规范，又要重视和分析设计签名的特点，通过设计者、签名用途和书写条件等特征数量和质量的衡量标准，进而形成更加符合设计签名书写习惯的综合评断。     

浅析摹仿签名笔迹鉴定

摹仿签名笔迹检验是笔迹检验的难点,认定签名摹仿人更是难中之难;笔者通过正确确定签名笔迹的真伪,从签名笔迹的概貌特征和细节特征之中运用辩证的观点正确认定摹仿人。     

Forensic Analysis of Digital Dynamic Signatures: New Methods for Data Treatment and Feature Evaluation

This study explored digital dynamic signatures containing quantifiable dynamic data. The change in data content and nature necessitates the development of new data treatment approaches. A SignPad Omega digitizing tablet was used to assess measurement reproducibility, as well as within‐writer variation and the occurrence of correctly simulated features. Measurement reproducibility was found to be high except for pressure information. Within‐writer variation was found to be higher between days than on a same day. Occurrence of correct simulation was low for features such as signature size, trajectory length, and total signature time. Feature discrimination factors combining within‐writer variability and the occurrence of correctly simulated features were computed and show that signature size, trajectory length, and signature time are the features that perform the best for discriminating genuine from simulated signatures. A final experiment indicates that dynamic information can be used to create connections between simulation cases.     

The dynamic character of disguise behavior for text-based, mixed, and stylized signatures

The aims of this study were to determine if dynamic parameters (duration, size, velocity, jerk, and pen pressure) differed for signing style (text-based, stylized, and mixed) and if signing style influences handwriting dynamics equally across three signature conditions (genuine, disguised, and auto-simulation). Ninety writers provided 10 genuine signatures, five disguised signatures, and five auto-simulated signatures. All 1800 signatures were collected using a digitizing tablet resulting in a database of each signature's dynamic characteristics. With genuine signatures, there were significant differences between styles for size, velocity, and pen pressure, and there were significant differences between genuine signatures and at least one of the un-natural signature conditions for all parameters. For velocity and size, these changes with condition were dependent on style. Changes with condition for the other parameters were similar for the three styles. This study shows that there are differences among natural signature styles and disguise behaviors that may be relevant in forensic signature examinations.     

Dynamic Characteristics of Signatures: Effects of Writer Style on Genuine and Simulated Signatures

The aims of this study were to determine if computer‐measured dynamic features (duration, size, velocity, jerk, and pen pressure) differ between genuine and simulated signatures. Sixty subjects (3 equal groups of 3 signature styles) each provided 10 naturally written (genuine) signatures. Each of these subjects then provided 15 simulations of each of three model signatures. The genuine (N = 600) and simulated (N = 2700) signatures were collected using a digitizing tablet. MovAlyzeR^® software was used to estimate kinematic parameters for each pen stroke. Stroke duration, velocity, and pen pressure were found to discriminate between genuine and simulated signatures regardless of the simulator's own style of signature or the style of signature being simulated. However, there was a significant interaction between style and condition for size and jerk (a measure of smoothness). The results of this study, based on quantitative analysis and dynamic handwriting features, indicate that the style of the simulator's own signature and the style of signature being simulated can impact the characteristics of handwriting movements for simulations. Writer style characteristics might therefore need to be taken into consideration as potentially significant when evaluating signature features with a view to forming opinions regarding authenticity.     

Automated comparisons of bullet striations based on 3D topography

A system capable of comparing the signatures on bullets in the field of firearms identification is presented. It is based on the recording of the topography of a bullet using laser profilometry. A procedure to derive a one-dimensional array of characteristics out of the recorded data is presented. These so-called feature vectors are compared with similar quantities from other bullets using a correlation technique. Good results were obtained for weapons leaving well-defined characteristics.     

A Prototype of Mathematical Treatment of Pen Pressure Data for Signature Verification

A prototype using simple mathematical treatment of the pen pressure data recorded by a digital pen movement recording device was derived. In this study, a total of 48 sets of signature and initial specimens were collected. Pearson's correlation coefficient was used to compare the data of the pen pressure patterns. From the 820 pair comparisons of the 48 sets of genuine signatures, a high degree of matching was found in which 95.4% (782 pairs) and 80% (656 pairs) had rPA > 0.7 and rPA > 0.8, respectively. In the comparison of the 23 forged signatures with their corresponding control signatures, 20 of them (89.2% of pairs) had rPA values < 0.6, showing a lower degree of matching when compared with the results of the genuine signatures. The prototype could be used as a complementary technique to improve the objectivity of signature examination and also has a good potential to be developed as a tool for automated signature identification.     

Cocaine profiling for strategic intelligence, a cross-border project between France and Switzerland: part II. Validation of the statistical methodology for the profiling of cocaine

Harmonisation and optimization of analytical and statistical methodologies were carried out between two forensic laboratories (Lausanne, Switzerland and Lyon, France) in order to provide drug intelligence for cross-border cocaine seizures. Part I dealt with the optimization of the analytical method and its robustness. This second part investigates statistical methodologies that will provide reliable comparison of cocaine seizures analysed on two different gas chromatographs interfaced with a flame ionisation detectors (GC-FIDs) in two distinct laboratories. Sixty-six statistical combinations (ten data pre-treatments followed by six different distance measurements and correlation coefficients) were applied. One pre-treatment (N+S: area of each peak is divided by its standard deviation calculated from the whole data set) followed by the Cosine or Pearson correlation coefficients were found to be the best statistical compromise for optimal discrimination of linked and non-linked samples. The centralisation of the analyses in one single laboratory is not a required condition anymore to compare samples seized in different countries. This allows collaboration, but also, jurisdictional control over data.     

Signature authentication by forensic document examiners.

We report on the first controlled study comparing the abilities of forensic document examiners (FDEs) and laypersons in the area of signature examination. Laypersons and professional FDEs were given the same signature-authentication/simulation-detection task. They compared six known signatures generated by the same person with six unknown signatures. No a priori knowledge of the distribution of genuine and nongenuine signatures in the unknown signature set was available to test-takers. Three different monetary incentive schemes were implemented to motivate the laypersons. We provide two major findings: (i) the data provided by FDEs and by laypersons in our tests were significantly different (namely, the hypothesis that there is no difference between the assessments provided by FDEs and laypersons about genuineness and nongenuineness of signatures was rejected); and (ii) the error rates exhibited by the FDEs were much smaller than those of the laypersons. In addition, we found no statistically significant differences between the data sets obtained from laypersons who received different monetary incentives. The most pronounced differences in error rates appeared when nongenuine signatures were declared authentic (Type I error) and when authentic signatures were declared nongenuine (Type II error). Type I error was made by FDEs in 0.49% of the cases, but laypersons made it in 6.47% of the cases. Type II error was made by FDEs in 7.05% of the cases, but laypersons made it in 26.1% of the cases.     

Stature Estimation from Hand Dimensions in a Han Population of Southern China*

Abstract: To analyze the relationship between stature and hand dimensions for forensic applications, the stature and hand dimensions of 400 healthy adults aged between 20 and 25 years were measured in a Han population of Southern China. The mean values of the stature are 170.49 and 159.72 cm in the men and the women, respectively. The statistically significant differences between the right‐ and the left‐hand dimensions were not observed in the men, whereas the bilateral differences are statistically significant in female hand dimensions. The correlation coefficients were found to be statistically significant for the hand dimensions in both the sexes. The hand length showed higher correlation coefficients than the hand breadth in both sexes. Linear and multiple regressions were developed in this study; multiple regressions showed higher correlation coefficients than linear regressions. Two regression models could be used to estimate the stature from the hand dimensions in this population.     

Forensic handwriting examiners' expertise for signature comparison

This paper reports on the performance of forensic document examiners (FDEs) in a signature comparison task that was designed to address the issue of expertise. The opinions of FDEs regarding 150 genuine and simulated questioned signatures were compared with a control group of non-examiners' opinions. On the question of expertise, results showed that FDEs were statistically better than the control group at accurately determining the genuineness or non-genuineness of questioned signatures. The FDE group made errors (by calling a genuine signature simulated or by calling a simulated signature genuine) in 3.4% of their opinions while 19.3% of the control group's opinions were erroneous. The FDE group gave significantly more inconclusive opinions than the control group. Analysis of FDEs' responses showed that more correct opinions were expressed regarding simulated signatures and more inconclusive opinions were made on genuine signatures. Further, when the complexity of a signature was taken into account, FDEs made more correct opinions on high complexity signatures than on signatures of lower complexity. There was a wide range of skill amongst FDEs and no significant relationship was found between the number of years FDEs had been practicing and their correct, inconclusive and error rates.