刑事影像技术新体系

目的阐述刑事影像领域内影像技术及应用的现状和发展。方法从理论方面研究国内外刑事影像技术文献。结果提出了刑事影像影像技术新的框架体系。结论刑事影像技术三个主要组成部分是影像成像检验、影像分析检验和影像合成演示。     

To image a Macintosh

This article covers the basics of acquiring a disk image from a Macintosh computer. It details a number of techniques that are available to the forensic examiner and covers other related issues. These include the use of open Firmware to determine the date and time of the internal computer clock. Once the disk image has been obtained, the article then considers a number of ways that the Macintosh can be used in the examination of the image. The article concludes with a look at the future of the Macintosh computer in the light of the move to the Intel chipset.     

An unusual case of cranial image recognition

We encountered an unusual practical case of craniofacial identification recently. The peculiarity of the case was that the skull itself was not available for examination unlike other such common cases. The supplied material exhibits were, a nearly front view photograph of a skeletonized face and a front view face photograph of the suspected victim. Further, the condition of the skull during taking its photograph was such that its lower and the upper jaws were not in a normal closed condition. The procedure involved in dealing with such a complicated craniofacial identification problem would be quite interesting from a forensic investigator's point of view, since standard methods of skull identification like photo/video superimposition techniques were not at all applicable here. As such, the present case report provides the details of the multiphase procedure adapted by us in dealing with this abnormal case. A solution to this unprecedented craniofacial identification problem was worked out by appropriate exploration of a newly introduced digital image processing technique that is based on craniofacial symmetry perception. The procedure leads to the reconstruction of a superimposable cranial image with upper and lower teeth in normal closed condition for establishment of its identity in usual way.     

变造图像的压缩率变化规律研究

目的研究变造图像的压缩率变化规律。方法选择不同数码相机不同分辨率进行拍照,将拍照所得图像经过PHOTOSHOP7．0．1软件分别进行色阶、自动色阶、曲线、锐化、USM锐化、锐化边缘、进一步锐化处理。利用ACDSee6．0查看并记录原图像和处理后的图像的文件大小和压缩率。结果探索经过处理的数字图像压缩率的变化规律,根据其变化规律来鉴定数字图像的原始性。     

Color separation in forensic image processing

In forensic image processing, it is often important to be able to separate a feature from an interfering background or foreground, or to demonstrate colors within an image to be different from each other. In this study, a color deconvolution algorithm that could accomplish this task is described, and it is applied to color separation problems in document and fingerprint examination. Subtle color differences (sometimes invisible to the naked eye) are found to be sufficient, which is demonstrated successfully for several cases where color differences were shown to exist, or where colors were removed from the foreground or background. The software is available for free in the form of an Adobe Photoshop-compatible plug-in.     

Pistol image retrieval by shape representation

Databases have been used to record data in forensic science, such as fingerprints, shoeprints, and photos. In traditional databases, we use “text” as the “keyword” for retrieving data (text-keyword retrieval); however, in some applications, “text” is not proper to describe the searching target, and in this case, “image” plays an important role. In this paper, we use “image features” as the “keywords”, and show its potential for building up a prototype of pistol image databases.In current firearm databases of forensic science, the retrieval method is still by text-keyword retrieval. For experienced forensic examiners, this kind of databases may satisfy their requirement. However, for people who have little gun knowledge, how can they find the possible gun candidates or similar guns in the databases, if there are not any available words or marks on the gun? In this paper, we try to retrieve similar pistol images by the pistol shape instead of “text-keyword”. This method can narrow down the searching range while identifying pistols by firearm databases.There are more than 300 pistol images in our pistol image database. From the experimental results, we can retrieve the similar pistol images in top five candidates for each pistol image.     

Efficient height measurement method of surveillance camera image

As surveillance cameras are increasingly installed, their films are often submitted as evidence of crime, but very scant detailed information such as features and clothes is obtained due to the limited camera performance. Height, however, is relatively not significantly influenced by the camera performance. This paper studied the height measurement method using images from a CCTV. The information on the height was obtained via photogrammetry, including the reference points in the photographed area and the calculation of the relationship between a 3D space and a 2D image through linear and nonlinear calibration. Using this correlation, this paper suggested the height measurement method, which projects a 3D virtual ruler onto the image. This method has been proven to offer more stable values within the range of data convergence than those of other existing methods.     

影像医学在法医学中的应用

个体识别在法庭科学调查中一直是重要的工作,它包括:性别、身高、年龄的推断等。在法庭科学领域中利用影像医学技术进行个体识别,在准确性、实用性方面有特别的意义。本文目的旨在通过广泛系统地回顾国内外法庭科学中的影像学应用,了解现有医学影像技术在法庭科学应用中的优点和不足之处,为进一步完善医学影像学在法庭科学中的应用提供参考。     

Age estimation by IBAS image analysis of teeth

The study of teeth to estimate age in a cadaver or in remains has become widely accepted in legal medicine, especially since the appearance of Gustafson's work in 1950. However, many studies published since that time have questioned the accuracy of these determinations. Computerized image analysis (IBAS) provides much more precise measurements of the parameters involved in these studies. An IBAS I (Kontron) image analysis system was used to study 19 different morphological parameters in midsagittal sections of a total of 173 upper and lower central incisors from as many live subjects. The data thus obtained provide useful information for determining the subject's age.     

Shoeprint image retrieval and crime scene shoeprint image linking by using convolutional neural network and normalized cross correlation

A shoeprint image retrieval process aims to identify and match images of shoeprints found at crime scenes with shoeprint images from a known reference database. It is a challenging problem in the forensic discipline of footwear analysis because a shoeprint found at the crime scene is often imperfect. Recovered shoeprints may be partial, distorted, left on surfaces that do not mark easily, or perhaps come from shoes that do not transfer marks easily. In this study, we present a shoeprint retrieval method by using a convolutional neural network (CNN) and normalized cross-correlation (NCC). A pre-trained CNN was used to extract features from the pre-processed shoeprint images. We then employed NCC to compute a similarity score based on the extracted image features. We achieved a retrieval accuracy of 82% in our experiments, where a “successful” retrieval means that the ground truth image was returned in the top 1% of returned images. We also extend our shoeprint retrieval method to the problem of linking shoeprints recovered from crime scenes. This new method can provide a linkage between two crime scenes if the two recovered shoeprints originated from the same shoe. This new method achieved a retrieval accuracy of 88.99% in the top 20% of returned images.     

Fast indexing strategies for robust image hashes

Similarity preserving hashing can aid forensic investigations by providing means to recognize known content and modified versions of known content. However, this raises the need for efficient indexing strategies which support the similarity search. We present and evaluate two indexing strategies for robust image hashes created by the ForBild tool. These strategies are based on generic indexing approaches for Hamming spaces, i.e. spaces of bit vectors equipped with the Hamming distance. Our first strategy uses a vantage point tree, and the second strategy uses locality-sensitive hashing (LSH). Although the calculation of Hamming distances is inexpensive and hence challenging for indexing strategies, we improve the speed for identifying similar items by a factor of about 30 with the tree-based index, and a factor of more than 100 with the LSH index. While the tree-based index retrieves all approximate matches, the speed of LSH is paid with a small rate of false negatives.     

显带染色体电子计算机辅助分析

应用委托开发的软件“中国人群区带染色体辅助分析系统”对国人染色体G带相片进行电子计算机分析。结果显示，该软件能有效快速地记录各个体核型，并能对不同个体来源的相同序号的染色体作直观比较．为染色体多态性应用于亲子鉴定创造了良好条件．     

Fingerprint image enhancement by differential hysteresis processing

A new method to enhance defective fingerprints images through image digital processing tools is presented in this work. When the fingerprints have been taken without any care, blurred and in some cases mostly illegible, as in the case presented here, their classification and comparison becomes nearly impossible. A combination of spatial domain filters, including a technique called differential hysteresis processing (DHP), is applied to improve these kind of images. This set of filtering methods proved to be satisfactory in a wide range of cases by uncovering hidden details that helped to identify persons. Dactyloscopy experts from Policia Federal Argentina and the EAAF have validated these results.     

Biomedical image processing for age measurements of intact teeth

With increasing age the roots of teeth undergo sclerosis. The degree of dental root sclerosis can be demonstrated visually if light is transmitted through the specimen. However, this resultant image is only a two-dimensional (2-D) visualization which misrepresents what in truth is a three-dimensional (3-D) characteristic. We have described an image acquisition and computer processing system for imaging intact teeth, with special reference to the root transparency, which tends to progress from the root apex towards the neck of the teeth as a function of age. The components of our system involve: an energy source with light transmission through table-mounted dental specimens; an image processor with a digitizer; a step motor with a holder to rotate the tooth specimen; and a software package to computerize and reconstruct the sectional digital images. After rotating the position of the specimen, while at each rotation obtaining a 2-D image of the sample, we then can reconstruct the true 3-D cross-sectional or longitudinal morphology or both from these 2-D images. With this new approach, the reconstructed dental images represent segments from different angles of the tooth specimen. Picture element values in each image, quantitatively indicate the optical density, expressing the age dependent pattern of the 3-D anatomy in toto.     

浅谈图像处理技术在侦查破案的运用

随着经济的发展和科技的进步,图像处理技术在打击违法犯罪方面发挥了越来越大的作用,尤其在侦查破案方面,图像处理技术可以为侦查破案提供诉讼和审讯等方面的证据,并可以提供侦查线索、方向、缩小侦查范围以及为采取侦查措施手段提供条件。同时,要运用好图像处理技术也要注意几个方面的问题。     

为“科技强警”建造信息高速公路——对话北京蛙视董事长陈瑞军

5月中旬，公安部、科技部联合在江苏省宿迁市召开全国第二批科技强警示范城市建设经验交流现场会。[第一段]