复印文件底灰量化检测的实验研究

本文首先阐述了利用计算机进行底灰量化检测的原理,实现了复印文件底灰的量化检测软件,而后通过实验验证了量化检测软件可以有效的检测出不同复印文件底灰的轻重,为复印件底灰的判定提供了一种新方法。     

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。     

试析网络环境下湖北公安文献保障体系的文献信息服务

本文从文献外借、文献阅览、联机书目检索、参考咨询、计算机信息检索、网络信息资源导航服务等六个方面探讨了网络环境下湖北公安文献保障体系的文献信息服务模式的提供。     

公安机关公文诚信状况分析和对策研究

目前,中国正处于社会转型期,法制与道德建设均存在诸多缺陷,"假冒伪劣"、"道德失范"、等不良风气也蔓延到了公安机关公文之中。公安机关公文诚信弱化,甚至造假失真,原因是多方面的,既有经济、政治方面的原因,更有道德、个人方面的因素。公安机关公文诚信缺失,状况堪忧,应当引起高度重视,应采取有效对策切实解决这一重要问题。     

A Preliminary Study on Sources of Banding Artifacts for the Identification of Monochromatic Laser Printers,

The analysis of questioned documents printed with monochromatic toner has been a great challenge to document examiners. Banding artifacts, which are often perceived in the outputs of laser printers, could be a solution to the identification of printers. In this study, sources other than the gear transmission errors were discovered for some primary banding frequency components. By detecting the angular velocity variation of photosensitive drums and other rotating parts of the tested printers and comparing them with the banding signals extracted from the printouts, the authors located the sources of banding frequency components. It was shown that the sources of some primary and persistent banding signals, which were previously unknown, were traced to the periodic velocity variations of the motors or the timing belts. As inherent signatures, banding artifacts could be promising features for discriminating documents printed by individual laser printers.     

Examination of a "velasco" signature on an oil painting

In September 2003, an investor bought an oil painting at auction in Denmark. The painting was signed "José Maria Velasco." The investor attempted to sell the painting in the United States, but found that he needed confirmation that this was an authentic Velasco painting. The provenance of the painting was questionable because it came to Europe from Cuba without appropriate documentation including the date of its entry into the European market. If the signature was determined to be authentic, the painting would have an approximate value of 1 million dollars. Initial research on the life and works of the artist and a literature review resulted in the preparation of an "Art Worksheet." Known signature specimens were obtained from reputable sources. A comparison of the known signatures with the questioned signature concluded the questioned signature was very probably not executed by José Maria Velasco.     

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.     

Identification of document paper using hybrid feature extraction

Document forgery is a significant issue in Korea, with around ten thousand cases reported every year. Analyzing paper plays a crucial role in examining questionable documents such as marketable securities and contracts, which can aid in solving criminal cases of document forgery. Paper analysis can also provide essential insights in other types of criminal cases, serving as an important clue for solving cases such as the source of a blackmail letter. The papermaking process generates distinct forming fabric marks and formations, which are critical features for paper classification. These characteristics are observable under transmitted light and are created by the forming fabric pattern and the distribution of pulp fibers, respectively. In this study, we propose a novel approach for paper identification based on hybrid features. This method combines texture features extracted from images converted using the gray-level co-occurrence matrix (GLCM) approach and a convolutional neural network (CNN), with another set of features extracted by the CNN using the same images as input. We applied the proposed method to classification tasks for seven major paper brands available in the Korean market, achieving an accuracy of 97.66%. The results confirm the applicability of this method for visually inspecting paper products and demonstrate its potential for assisting in solving criminal cases involving document forgery.     

Rapid and non-destructive approach for characterization and differentiation of sealing wax using ATR-FTIR spectroscopy

Sealing wax is used for maintaining the integrity and authenticity of a document or physical evidence. Any tampering with the seal calls into question the overall integrity and authenticity of the tangible evidence or document. In these circumstances, determining the authenticity of the sealing material (physical and chemical) becomes imperative. In this study, ATR-FTIR spectroscopy supported by chemometrics has been used to differentiate sealing wax samples belonging to 12 different brands available across India. All the samples were first melted, cooled, and then analyzed using ATR-FTIR spectroscopy in the mid-infrared region (4000–600 cm⁻¹). The obtained spectra were first examined visually for the presence of different functional groups. Principal component analysis (PCA) and principal component analysis-linear discriminant analysis (PCA-LDA) were employed to analyze the sample clustering patterns and to categorize them into their respective groups, respectively. For classification, a PCA-LDA training model was applied, and it demonstrated 95.83% accuracy. The validation test resulted in an accuracy of 83.33%. PCA-LDA model offered 100% accurate prediction for samples on various substrates, including cloth, cardboard, and paper. A blind study was also performed using five unknown samples, which were accurately classified into their respective groups. PCA-LDA model will be helpful in providing investigative leads by linking a questioned sealing wax sample with its respective group.     

The Decipherment of Latent White Board Entries

This case involves an incriminating message written on a white board and erased before the investigators seized the evidence. Investigators inquired about the possibility of recovering the entries and subsequently submitted the board to the Documents and Digital Evidence Branch for examination. In an attempt to recover latent handwritten entries, examinations were conducted utilizing the Foster and Freeman Video Spectral Comparator 6000/Hyper Spectral (VSC 6000/HS). Latent handwritten entries were observed with the use of an excitation band‐pass filter in the range of 485 nm‐610 nm with a longpass barrier filter at 645 nm in front of the camera lens of the VSC 6000/HS. Entries were also recovered and imaged using an alternate light source with the Phase One (P65) imaging system. Multiple latent handwritten entries were recovered utilizing various instruments and lighting techniques. This report discusses the details concerning the examination and the results.