利用ImageXpress系统灰度特征区分激光打印复印一体机的打印及复印文件初探

目的探索区分激光打印复印一体机的打印文件及复印文件的方法。方法利用ImageXpress系统对理光MP4000BSP激光打印复印一体机的打印文件和复印文件进行灰度特征值的测量。结果两种文件的灰度平均值的平均值和95%置信区间存有明显的差异,且这种差异较为稳定：打印件的平均值约为50,而复印件约为53;打印件的95%置信区间介于50和51.5之间,而复印件的置信区间介于52.5与54之间。结论本方法通过量化对激光打印复印一体机打印及复印文件进行区分是可行的。     

打印复印文件朱墨时序表观特征初探

本文详细介绍了一案例的检验过程,并通过简单实验对激光打印、静电复印形成文件的朱墨时序的表观特征进行了粗浅的探究。总体而言,两种时序在朱墨交叉点的表观特征上具有文字与印文均完整、肉眼感觉文字均压在印文之上的共同点;在两者本质的差异点上,先朱后墨表现为交叉点的墨粉与未交叉部位一致,先墨后朱表现为交叉点的墨粉光泽度增加、具有潮湿感、以及易出现水珠状的印油积聚现象。     

常用彩色激光打印机打印文件暗记特征的初步研究

目的收集当前我国常用不同品牌和型号的彩色激光打印机打印样本,研究打印文件上暗记特征的提取分析及其变化规律,探讨彩色激光打印文件暗记特征在鉴定实践中的应用及其在打印文件防伪措施中的价值。方法使用显微镜、文检仪及有关图像处理技术分别检验了彩色激光打印机的打印文件样本。结果彩色激光打印机打印文件上会出现暗记特征,且不同品牌的暗记特征出现规律、形态特征和点阵特征不同。结论暗记特征可作为初步鉴别彩色激光打印机品牌型号及打印时间的依据,具有防伪价值,但其在鉴定实践中还存在一定的局限性,有待进一步研究。     

利用彩色文件上的图文特征鉴别喷墨打印机品牌

目的通过彩色文件上的图文特征鉴别喷墨打印机的品牌。方法在体视显微镜下观察采用不同喷墨机理的惠普、佳能和爱普生三大品牌喷墨打印机打印的彩色图文。结果通过对彩色图文上六种墨迹形态特征的比较,发现三大品牌喷墨打印机打印的彩色图文存在明显差异。结论依据这六种特征对三大品牌的喷墨打印机进行鉴别。     

添加打印变造文件检验1例

1 案件简介某公安局经侦部门送来某公司股东会决议1张,要求鉴定检材上正文第三段可疑打印字迹与第一、二段字迹是否为一次打印形成.据报案人称检材上第三段字迹为后添加形成的.2 讨论检材为A4幅面,经检验检材上第三段可疑打印字迹由碳粉颗粒组成,面缘整齐,为激光打印机打印形成;其上第一段、第二段字迹经放大观察发现字迹也由碳粉颗粒组成,面缘整齐,反映出激光打印机打印文件的特点[1](见图1),故检材第一、二段与第三段均为激光打印机打印形成,显微观察墨粉分布形态未见差异.     

复印“露白”特征在文检中的运用

当前在文检界对复印文件的检验有待深入研究和探讨。在复印文件检验中,文检人员比较注重复印过程中形成的“疵点”和“划痕”,而对“露白”部分研究不够。实际上,“露白”特征在多次复印的文件检验过程中,对认定前后两次复印之间的关系具有重要作用。笔者结合近期侦破的一起案例,对“露白”特征在多次复印文件检验中的运用,作一报导,望能引起同行们的关注。１复印“露白”及其形成复印,是通过复印机对文件原件进行复制的过程。从理论上讲,复印应该是真实复制原件的过程。但实际情况并非如此。由于受设备零部件、粉末和纸张等条件的…     

利用感光鼓损伤印迹确定激光打印件的相对形成时间

目前，司法鉴定中各种有争议的文件物证，往往存在被伪造的可能，其中更换合同中的打印件，在各类民事诉讼案件中出现频率较高，检验难度较大。如何利用无损检验方法揭示文件有无伪造及如何伪造，是鉴定人员面临的问题。本文介绍了利用感光鼓损伤印迹确定激光打印件相对形成时间的一种无损检验的方法。     

多光谱成像技术检验富士施乐C4300彩色激光打印复印一体机形成文件

目的研究富士施乐C4300彩色激光打印复印一体机形成文件的跟踪暗码,对富士施乐C4300彩色激光打印复印一体机形成文件进行识别。方法使用多光谱成像仪对6台富士施乐C4300彩色激光打印复印一体机形成的文件进行观察。结果该6台机器形成文件的跟踪暗码存在特征差异。结论通过跟踪暗码的差异,能够对富士施乐C4300彩色激光打印复印一体机形成文件进行识别。     

三维立体显微镜在文件检验中的应用

目的通过应用先进的仪器设备,让我们从另一个角度观察文检痕迹特征,寻找到一个文件检验的新视角。方法利用三维立体显微镜,从微观的三维状态下分析文检的痕迹特征(上下位置)。结果能有效区别笔迹书写与印章的先后顺序;打印字迹和印章的先后顺序,同一支笔书写形成的交叉笔划的先后顺序;准确区别打印文书和复印文书等。结论借助三维立体显微镜,能使文件检验水平向前迈进一步。     

无交叉笔画状态下激光打印文字与中性笔书写文字形成时序的实验研究

目的探索无交叉笔画状态下激光打印文字与中性笔书写文字的时序特征及变化规律,以求运用于案件检验。方法以两种不同时序,请5名志愿者分别执不同中性笔在120张A4纸张上书写文字,并使用4台不同型号激光打印机打印文字,再运用奥博视频层晰显微镜对实验样本进行放大观察。结果证实在两种时序条件下制作的实验样本之间存在诸多差异性特征。结论这些差异性特征为准确判定无交叉笔画状态下激光打印文字与中性笔书写文字的时序提供了基础实验依据。     

利用数字图像处理技术伪造文件的研究

介绍了利用数字图象处理技术剪贴伪造文件、变造签名、彩色打印伪造原始印文和签名等三种伪造文件的方法及其特点.数字图象处理技术能够克服许多传统伪造方法的"缺点",使伪造的文件达到较高的逼真度.讨论了数字图象处理技术的滥用引发的新问题.     

Investigating forensic document examiners’ skill relating to opinions on photocopied signatures

Many forensic document examiners are hesitant to express authorship opinions on photocopied handwriting as the photocopying process results in less feature information than original writing. This study aimed to test the accuracy of 15 examiners' opinions regarding whether photocopied questioned signatures were genuine or simulated. Each examiner received the same set of original signature exemplars, from one individual, and a set of eighty questioned photocopied signatures comprising of genuine and simulated signatures. The overall misleading (error) rate for the grouped examiners' opinions was 0.9% providing strong evidence that examiners can make accurate observations regarding the authorship of non-original handwriting.     

An insight into forensic document examiner expertise for discriminating between forged and disguised signatures

It has previously been shown that forensic document examiners (FDEs) have expertise in providing opinions about whether questioned signatures are genuine or simulated. This study extends the exploration of FDE expertise by evaluating the performance of eight FDEs and 12 control subjects at identifying signatures as either forgeries or the disguised writing of a specimen provider. Subject eye movements and response times were recorded with a Tobii 1750 eye tracker during the signature evaluations. Using a penalty scoring system, FDEs performed significantly better than control subjects (t = 2.465, p = 0.024), with one FDE able to correctly call 13 of the 16 test stimuli (and three inconclusive calls). An analysis of eye movement search patterns by the subjects indicated that a very similar search strategy was employed by both groups, suggesting that visual inspection of signatures is mediated by a bottom up search strategy. However, FDEs spent greater than 50% longer to make a decision than the control group. The findings are suggestive that for some stimuli FDEs can discriminate between forgeries and disguises, and that this ability is due to a careful inspection and consideration of multiple features within a signature.     

Passport examination by a confocal-type laser profile microscope

The author proposes a nondestructive and highly precise method of measuring the thickness of a film pasted on a passport using a confocal-type laser profile microscope. The effectiveness of this method in passport examination is demonstrated. A confocal-type laser profile microscope is used to create profiles of the film surface and film–paper interface; these profiles are used to calculate the film thickness by employing an algorithm developed by the author. The film thicknesses of the passport samples—35 genuine and 80 counterfeit Japanese passports—are measured nondestructively. The intra-sample standard deviation of the film thicknesses of the genuine and counterfeit Japanese passports was of the order of 1 μm The intersample standard deviations of the film thicknesses of passports forged using the same tools and techniques are expected to be of the order of 1 μm. The thickness values of the films on the machine-readable genuine passports ranged between 31.95 μm and 36.95 μm. The likelihood ratio of this method in the authentication of machine-readable Japanese genuine passports is 11.7. Therefore, this method is effective for the authentification of genuine passports. Since the distribution of the film thickness of all forged passports was considerably larger than the accuracy of this method, this method is considered effective also for revealing the relation among the forged passports and acquiring proof of the crime.     

微束X射线荧光分析法鉴别激光打印机墨粉的研究

目的利用微束X射线荧光分析法（μ-XRF）研究激光打印机用墨粉的鉴别。方法利用μ-XRF对9台不同型号激光打印机用墨粉、对应的打印字迹、提取的字迹墨粉所含元素进行定性、半定量的分析。结果根据检出元素种类的不同,可将9台不同型号激光打印机用墨粉、对应的打印字迹、提取的字迹墨粉分成7类、4类、4类,区分率分别为94.4%、75%、69.4%。结论本研究所建立的μ-XRF鉴别激光打印机墨粉方法具有微区、原位无损检验等优点,对提高激光打印文件检验水平具有现实意义。     

The probative character of Forensic Handwriting Examiners' identification and elimination opinions on questioned signatures

This 5-year study investigated the character of Forensic Handwriting Examiners' (FHEs) authorship opinions on questioned signatures through the medium of blind validation trials. Twenty-nine thousand eight hundred and eleven authorship opinions were expressed by FHEs on trial kits comprising randomized questioned genuine signatures (written by the specimen writer), disguised signatures (written by the specimen writer) and simulated signatures (not written by the specimen writer). Results showed that, as a group, FHEs were significantly more confident at identifying writers' genuine signatures than identifying writers' disguised signatures or eliminating specimen writers from having authored simulated signatures. It is proposed that the difference in FHE confidence arises from the difficulty they have in deciding which alternative authorship explanation accounts for perceived combinations of similar and dissimilar features between specimen and questioned signatures.