基于过程解析法的同机添加打印文件鉴别方法

利用喷墨打印机二次添加打印,特别是同机添加打印变造文件,是文件检验工作中的难题。喷墨打印机采用串行接字方式,内部结构复杂,喷嘴数目多,同一型号打印机又有多种质量模式。因此,在打印图文上往往留有较多的打印特征,如对接重叠线、对接错位线、横向白线、卫星墨点、墨点错位等。分析爱普生、惠普、佳能三个品牌的20台喷墨打印机不同质量模式的打印文件,发现这些特征重复再现频率较高,不同台打印机打印文件特征差异较大,同一台打印机在不同质量模式下特征出现的位置也不尽相同。通过提取打印文件上的打印特征,分析字车运行方向和打印图文pass数值,分解打印过程并制作检验图谱,判断打印文件的可疑区域是否符合打印规律,为确定二次添加打印提供帮助,提升检验过程的规范性、检验意见的准确性和结果依据的可读性。     

显微共焦拉曼光谱技术区分喷墨打印机打印的彩色图文墨迹

目的建立显微共焦拉曼光谱法区分喷墨打印机打印的彩色图文墨迹的方法。方法利用显微共焦拉曼光谱技术所具有微量、微区、原位分析及非破坏性等特点,对24种常见彩色墨水墨迹分别进行检验。结果品红色墨点墨迹成分归类区分效果最好,其次是黄色墨点,最后是蓝色墨点。结论采用显微共焦拉曼光谱技术对彩色打印墨迹进行不同颜色单点分析可大大提高喷墨打印机厂家型号的识别率,是一种有效的检测手段。     

利用暗记特征鉴别彩色激光打印、复印文件

目的探讨激光打印机的暗记特征,为鉴别彩色激光打印、复印文件找到一种有效的方法。方法根据不同物质对光的反射特性及蓝色与黄色互补特性的原理,采用420nm左右蓝光照射方法,对部分品牌彩色激光打印、复印文件进行了初步分析研究,总结了暗记点阵形态特征、小点形态特征、出现位置特征和排列含义等特征。结果此方法对彩色激光打印、复印机具的种类鉴别和个体鉴别简便、有效。     

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。     

彩色打印机打印印文的检验

随着现代科学技术的发展,犯罪分子的作案手段正在向技术化、智能化发展。涉及印章案件由手工私刻印章,到电脑排版刻章,发展到现在利用计算机复制,通过彩色打印机打印到文件上的印章印文的伪造犯罪活动。1计算机复制打印印文的产生首先将所需要的原始印章印文用扫描仪扫描或摄像到计算机图文处理系统,然后对扫描的印文进行计算机背景处理,最后利用彩色打印机打印到所需要的文件纸张上。彩色打印机(喷墨打印机、激光打印机)是由黑色和彩色墨盒组成,彩色墨盒内是由三原色组成,分别是黄色、品红色、青色。计算机打印出的复制印章印文为红色,红色…     

化学显色法分析喷墨打印机黑色墨水的种类

目的建立化学显色法检验喷墨打印机字迹色痕的方法。方法选用不同的试剂或混合试剂,对22种不同品牌的喷墨打印黑色墨水的溶解性及与不同试剂的颜色反应进行观察。结果不同品牌的喷墨打印机黑色墨水的溶解性不同,与不同试剂作用会显现不同的颜色。结论化学显色法快速、简便,可用于现场的快速检验。     

喷墨打印机打印文件检验

喷墨打印机是计算机的外部设备,用于实现文件的硬拷贝,即将计算机对信息的处理结果打印在纸张上。近年来由于喷墨打印技术在社会上被广泛应用,据预测,未来喷墨打印机市场的份额将占60％。因此刑事文检人员将会越来越多地接触喷墨打印机打印的各类文件,需要判断其是何种类、机型、机台的打印机形成的,从而确定文件的来源和真伪,为侦查缩小范围,为法庭提供证据。     

喷墨打印文书的检验方法

随着计算机技术的进一步发展，办公自动化日益普及，打印机打印输出的经济合同、文本协议等文书在人们的社会生活中被广泛使用。在涉及经济领域的刑事犯罪中此类文书作为证据已愈现突出，需要司法部门检验鉴定文书来源、打印方式及其真伪性的工作量也不断增多。本文着重探讨喷墨打印文书的检验鉴定技术。喷墨打印技术是在９０年代中期迅猛发展起来的，市场占有率高，是目前企业和家庭办公自动化的主流机种。喷墨打印机是非击打式打印机。它通过向打印纸的相应位置喷射墨点实现图像和文字的输出。喷墨打印机分为固态喷墨和液态喷墨两种打印方…     

浅谈彩色打印图像的半色调结构特征

目的探讨利用彩色打印图像上的半色调结构特征进行种类鉴别的方法。方法通过对上百种彩色打印设备输出的实验样本进行放大观察和形态学特征比较,详细描述了半色调结构特征。结果发现半色调结构特征反映打印设备硬件和软件方面的固有特征,具有特殊性和稳定性,综合其构成的各个方面可以作为彩色打印设备机种鉴别的一个重要依据。     

添加打印文书检验方法新探

结合打印机工作原理,对打印机进纸、走纸机械构件不可避免的造成文书添加打印内容的图文字迹横轴线倾斜异常、行距异常、页边距异常该三方面共性特征的机械原理做出解构分析,对添加打印变造文书做出补充性的研究,进一步确证添加打印内容与原文书内容差异特征的客观存在。并介绍以photoshop图像处理软件为平台的更便捷、直观、高效的科学检验新方法,解决实际工作中运用以往机械比对方法难以实现添加打印变造文书检验目的情况。     

Examination of spur marks found on inkjet-printed documents

In this paper, we propose the examination of spur mark evidence on inkjet-printed documents. Spur marks are tool marks created by the spur gears in the paper conveyance system of many inkjet printers. The relationship between printouts and printers were investigated by comparing the spur marks found on printed documents with reference spur marks sampled from known printers. The comparison was based on two characteristics of spur marks: pitch and mutual distance. These characteristics extracted the geometric features of spur marks and provided information on the type of spur gears and their location in the paper conveyance system. The spur marks on a printout matched the reference spur marks within three percent of the measured values. Spur marks were considered to be effective class characteristics to identify certain brands of inkjet printers since spur gears are used in many types of these machines.     

The use of an electrostatic detection device to identify individual and class characteristics on documents produced by printers and copiers--a preliminary study

The market is inundated with inkjet printers, laser printers, and photocopiers, which are often used in criminal activities. Many of these office machines are built by various manufacturers, hence they are constructed with different hardware designs (e.g. "rolling" and "grabbing" mechanisms) that have changed over the years due to technological advances. Examinations of printed documents that involve the chemical analysis of ink colorants and the identification of physical machine defects such as trash marks are essential for the forensic examiner, but new techniques are needed to more closely identify a machine model or group of models. An electrostatic detection device (EDD) provide forensic examiners with a nondestructive method to examine indentations on a document. In this work, an EDD is used to detect latent physical markings left on documents by printers and photocopiers. Seventeen inkjet printers, 12 laser printers, and 3 photocopy machines were used to produce test documents. Physical markings were detectable in the large majority of the documents and were reproducible 100% of the time.     

Visualizing latent fingerprints on color-printed papers using ultraviolet fluorescence

Laser detection of latent fingerprints on a white paper has been performed, previously. Ultraviolet fluorescence from various kinds of printer toner and ink used for home printers were measured to study fluorescence imaging of fingerprints on a color-printed white paper. The experimental system consisted of a nanosecond pulsed tunable laser and a cooled CCD camera. Excitation wavelengths are 230 and 280 nm. Fourteen printers consisting of three color laser printers, three color inkjet printers, five monochrome laser printers, two monochrome copy machines, and a color copy machine were tested. Toner and ink of most printers exhibited fluorescence in the region from 360 to 550 nm. In most cases, clear fluorescence images were obtained by time-resolved imaging with a band-pass filter and 280-nm excitation. However for toners from laser color printers that showed strong fluorescence, better results were obtained with 230-nm excitation. Latent fingerprints on a photograph page and a black-character page of a newspaper were also imaged.     

Classification algorithm using halftone features of counterfeit bills and CNN

With recent advancements in image processing and printing technology, home printers have improved in performance and grown more widespread. As such, they have been increasingly used in counterfeiting and forgery. Most counterfeit bills in Korea have been created using home scanners and printers. The identification of printer model is thus necessary to rapidly track down criminals and solve crimes. Household printers can be largely divided into inkjet and laser printers. These two types of printers print halftone textures instead of continuous images. This study proposed a technique of printer classification based on halftone textures that can be observed in printed documents. Since halftone textures are expressed as periodic lattices, the images were transformed via FFT, which is highly effective at expressing periodicity. ResNet, known for its superior gradient flow, was used for training. The experiment was conducted on 12 color laser jets and 2 inkjets. Scans of bills printed by each printer were used, and halftone texture analysis was performed on these images for printer model classification. Each image was cropped into several parts; one of the cropped parts was analyzed. The analysis showed that laser printers could be 100% distinguished from inkjet printers. An accuracy of 98.44% was achieved in make classification. When 50 cropped images were used instead of a single image, the technique achieved 100% accuracy in model classification. The proposed technique is non-destructive; it offers high accessibility and efficiency as it can be performed using a scanner alone, without requiring additional optical equipment.     

Raman spectroscopy and laser desorption mass spectrometry for minimal destructive forensic analysis of black and color inkjet printed documents

Inkjet ink analysis is the best way to discriminate between printed documents, or even though more difficult, to connect an inkjet printed document with a brand or model of printers. Raman spectroscopy and laser desorption mass spectrometry (LDMS) have been demonstrated as powerful tools for dyes and pigments analysis, which are ink components. The aim of this work is to evaluate the aforementioned techniques for inkjet inks analysis in terms of discriminating power, information quality, and nondestructive capability. So, we investigated 10 different inkjet ink cartridges (primary colors and black), 7 from the HP manufacturer and one each from Epson, Canon and Lexmark. This paper demonstrates the capabilities of three methods: Raman spectroscopy, LDMS and MALDI-MS. Raman spectroscopy, as it is preferable to try the nondestructive approach first, is successfully adapted to the analysis of color printed documents in most cases. For analysis of color inkjet inks by LDMS, we show that a MALDI matrix (9-aminoacridine, 9AA) is needed to desorb and to ionize dyes from most inkjet inks (except Epson inks). Therefore, a method was developed to apply the 9AA MALDI matrix directly onto the piece of paper while avoiding analyte spreading. The obtained mass spectra are very discriminating and lead to information about ink additives and paper compositions. Discrimination of black inkjet printed documents is more difficult because of the common use of carbon black as the principal pigment. We show for the first time the possibility to discriminate between two black-printed documents coming from different, as well as from the same, manufacturers. Mass spectra recorded from black inks in positive ion mode LDMS detect polyethylene glycol polymers which have characteristic mass distributions and end groups. Moreover, software has been developed for rapid and objective comparison of the low mass range of these positive mode LDMS spectra which have characteristic unknown peaks.     

Differentiation of coloured inks of inkjet printer cartridges by thin layer chromatography and high performance liquid chromatography

Document examiners are frequently asked to determine whether or not a colour printout has originated from a particular inkjet printer. The printer can rarely be identified unless some unique defects or irregularities of the printer are present on the printout. However, it is possible to decipher the make and/or model of the printer by comparing the ink-profile of the questioned printout with that of a seized inkjet printer cartridge or from one in a database. This paper presents an overview of a systematic approach to characterising and discriminating the inks of different inkjet printer cartridges using thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC) with multi-wavelength ultra-violet/visible (UV/Vis) detection. Ink samples from 23 different inkjet printer cartridges (including originals and substitutes) of different brands and colour printouts, printed by known printers were examined with newly developed chromatographic methods. Subsequently, a database of the ink-profiles was generated. The methods provide a useful tool for discriminating coloured inks in inkjet printer cartridges of different brands.     

Application of capillary electrophoresis to examination of color inkjet printing inks for forensic purposes

In the process of questioned document examination, the discrimination of inkjet printing inks is becoming more necessary due to increasingly frequent counterfeiting of documents printed by inkjet printers. Therefore, a method based on micellar electrophoretic capillary chromatography (MECC) has been developed and applied to analysis of such inks extracted from paper. With the use of an optimized and validated analytical procedure, multielectropherograms of inks taken from various models of printers made by various producers (Hewlett-Packard, Epson, Brother, Lexmark and Canon) were created. It was shown that effective differentiation of individual inks was possible in terms of migration time, order and specific shapes of characteristic peaks. By comparison of recorded UV-Vis spectra, the identification of main dyes was also achievable. The usefulness of the method was confirmed by an intralaboratory test of utility, in which several forged printouts were successfully examined. The obtained results proved that the proposed procedure is a useful tool that could be applied to ink discrimination and group identification of dyes originating from inkjet printing inks. Consequently, the developed method can be applied in the forensic field, including investigation of the authenticity of documents.