数码影像技术在物证照相中的应用

随着数字技术的飞速发展，越来越多的刑事摄影人员发现，无论是影像信息采集、信息传递，还是影像处理、影像制作，数字影像技术与传统模拟影像技术由交互利用向完全取代的趋势发展，成为刑事技术领域多媒体应用技术重要的一部分。而数字相机、扫描仪正是生成数字影像的基本工具，尤其是随着图像处理软件和图像输出技术的进步，将数字影像技术推广应用于刑事技术工作，已显得越来越必需了。     

刑事图像技术的发展趋势

刑事图像是刑事科学技术的基础，它与痕迹、理化、文件、法医检验交织并存，互相渗透正朝着纪录、检验、识别、鉴定等多学科，全方位，综合性领域发展。目前的发展趋势如下：     

浅析刑事影像技术在案件侦查工作中的重要作用

近年来，刑事影像技术以其独特的优势，在刑事图像侦查工作中得到广泛的普及和应用，将刑事影像技术应用于刑事侦查工作可以帮助侦查人员迅速获取案件的线索并有效缩小侦查目标，有效提高侦查工作效率，本文从分析刑事影像技术对侦查、调查取证工作中的重要作用入手，叙述了刑事影像技术是运用影像方法对发生案件的地点和遗留犯罪痕迹、物证的场所，按照现场勘查的规定和办案工作的要求，把现场状况及痕迹物证的特点、位置等，如实地拍照、拍摄下来，为研究案情性质，分析作案手段，进行现场实验提供资料，为技术检验、鉴定提供条件，为起诉、审判提供证据。     

刑事图像技术的未来与发展

刑事图像是刑事科学技术领域中，发展最迅速的一个分支。它与痕迹、理化、文件、法医检验交织并存，互相渗透正朝着纪录、检验、识别、鉴定等多学科，全方位，综合性领域发展。     

数字图像处理技术在刑事技术工作中的应用

本文在分析数字图像技术优势的基础上,结合数字图像处理的内容,详细讨论了其在刑事技术工作中的应用,包括在刑事照相、低质量与模糊刑事图像增强、辅助物证检验、刑事图像分析与鉴定以及刑事图像重建演示中的应用。与传统摹拟图像处理技术相比,数字图像处理技术具有无可比拟的优势。     

浅谈低分辨率图像的核回归复原处理的运用体会

刑事图像检验工作中,图像或图像内目标低分辨率问题是普遍存在的,而简单的插值处理放大后得不到较好图像或图像轮廓。核回归复原处理可以较好解决这一问题,但在实际应用中存在运算速度慢和处理效果非万能的问题,并需要配合多种增强方式处理才能取得较好效果。本文简单介绍笔者的一些体会,希望核回归复原处理能被刑事图像检验工作者广泛运用。     

借助三色空间增强图像中指纹反差

如何部分地增强图像反差是刑事技术工作中最常遇到的难题之一。借助数字图像处理技术，可以根据像素值差异从原始图像提取感兴趣部分信息。本文讨论了这种基于像素值差异进行指纹背景分离的方法，可为指纹自动识别提供便利。     

刑事和解制度在我国的构建设想

由于刑事和解在一定程度上能够缓解受害人与加害人的矛盾，恢复其原本和睦的关系，弥补被害人所受到的伤害，并使犯罪人改过自新，复归社会，同时体现了公正效率的法律价值，也契合了我国构建和谐社会的时代理念，作为一种重要的诉讼理念和机制，刑事和解应当作为刑事诉讼中的一项基本制度加以确立。这不仅仅符合我国构建社会主义和谐社会的现实需要，对于健全我国法制有所裨益，更对世界关于刑事和解制度研究做出一次科学探索。本文主要通过对我国引人刑事和解制度的可能性，刑事和解范围以及运行模式三方面的论述提出在社会注意国家如何构建刑事和解制度的初步设想。     

刑事影像技术的作用

1　刑事影像科学技术刑事影像科学技术是公安机关、国家安全机关和人民检察院的侦察部门、刑事技术部门以及其它依法可以进行勘验检查和物证鉴定的机构 ,以光学、化学等为理论基础 ,依照法定程序和办案工作的要求 ,运用摄影、摄像等器材和影像技术 ,记录、显现和检验与犯罪及物证鉴定有关的客体的一种专门手段。刑事影像技术包括刑事摄影、刑事摄像和刑事图像处理技术 ,是刑事科学技术的重要组成部分。刑事影像技术在揭露和打击刑事犯罪的斗争中起着重要的作用。1 1　刑事影像技术分类(1)根据影像形成特性和方式分为 :刑事摄影、刑事摄像、…     

多媒体图像技术分析及应用

多媒体图像技术是多媒体系统中重要组成部分，其中，图像的压缩存储，图像显示和播放，视频交互，图像传输是多媒体系统得以实现和发展的重要基础。借助于开发工具，还可以制作图像产品。     

超分辨率图像重建在法庭科学中的应用

超分辨率图像重建是近年来迅速发展起来的一种旨在利用某一景物的若干低分辨率图像获取该景物高分辨率图像的技术。本文介绍了超分辨率图像重建技术在法庭科学中的应用、作用、方法,并总结了相关问题和发展方向。     

利用全光谱特种照相取证仪去除指印的背景干扰

目的：研究去除现场指印背景干扰的技术方法。方法：采用全光谱特种照相取证仪的主光源,以10—30度的入射角照射具有背景干扰的现场指印．并结合该设备的滤光系统进行分色照相。结果：显现出亮纹线暗背景的指印图像,指印背景无干扰。结论：采用全光谱特种照相取证仪可以消除指印的背景干扰,为指印显现提供了一种新的设备。     

Reliability-based failure cause assessment of collapsed bridge during construction

Until now, in many forensic reports, the failure cause assessments are usually carried out by a deterministic approach so far. However, it may be possible for the forensic investigation to lead to unreasonable results far from the real collapse scenario, because the deterministic approach does not systematically take into account any information on the uncertainties involved in the failures of structures.Reliability-based failure cause assessment (reliability-based forensic engineering) methodology is developed which can incorporate the uncertainties involved in structural failures and structures, and to apply them to the collapsed bridge in order to identify the most critical failure scenario and find the cause that triggered the bridge collapse. Moreover, to save the time and cost of evaluation, an algorithm of automated event tree analysis (ETA) is proposed and possible to automatically calculate the failure probabilities of the failure events and the occurrence probabilities of failure scenarios. Also, for reliability analysis, uncertainties are estimated more reasonably by using the Bayesian approach based on the experimental laboratory testing data in the forensic report. For the applicability, the proposed approach is applied to the Hang-ju Grand Bridge, which collapsed during construction, and compared with deterministic approach.     

Integrated survey methodology for the crime reconstruction

The object of this study is to evaluate the applicability of photogrammetry and laser scanner techniques both on forensic ballistic reports and on reproduction of crime scene. In the first case, in a shooting range for small arms, photogrammetric and laser were used both for the acquisition of metric data related to the testing environment and for ballistic simulation on a suitable sample. The crime scene was specifically simulated in laboratory, while the room where a murder took place was re-created. Once the setting had been made, it was possible to perform the survey of the scene and the details in it by using laser scanner and photogrammetric techniques. Data acquisition has enabled authors to carry out a rapid reconstruction of the scene and detect several parameters using the available elements. Specifically, the processed data were also exported to a CAD and an image processing software.     

Transformations for compositional data with zeros with an application to forensic evidence evaluation

In forensic science likelihood ratios provide a natural way of computing the value of evidence under competing propositions such as “the compared samples have originated from the same object” (prosecution) and “the compared samples have originated from different objects” (defence). We use a two-level multivariate likelihood ratio model for comparison of forensic glass evidence in the form of elemental composition data under three data transformations: the logratio transformation, a complementary log-log type transformation and a hyperspherical transformation. The performances of the three transformations in the evaluation of evidence are assessed in simulation experiments through use of the proportions of false negatives and false positives.     

3D imaging for bite mark analysis

Abstract

This work describes the investigation into a new 3D capture method for acquisition and subsequent forensic analysis of bite mark injuries on human skin. When documenting bite marks with standard 2D cameras, errors in photographic technique can occur if best practice is not followed. Subsequent forensic analysis of the mark is problematic when a 3D structure is recorded in a 2D space. A 3D image capture and processing system might avoid the problems resulting from the 2D reduction process, simplifying the guidelines and reducing errors. This paper reviews current 2D and three 3D capture methods and proposes a series of benchmarks for system assessment. This is followed by a series of performance evaluations of the existing current 2D and two 3D methods. Further proposed solutions include the design of a system specification for the practical reproducible acquisition of bite mark injuries and a review of the validation process for forensic evidence presented to the courts. The result of this work is that a 3D system is required to produce the correct 3D data of a bite mark and suspect dentition for forensic analysis. Such a system should be practical and consistent if it is to replace the current de facto 2D systems. The MAVIS hardware, for example, can be considered a practical and consistent solution for producing the required 3D image of a bite mark for analysis; however, the MAVIS hardware cannot produce a satisfactory 3D image of a dental cast. At present, a laser scanner is required to produce satisfactory results of a dental cast. Angular distortion and errors created by the user in 2D image capture can hinder the digital measurement process. 3D capture therefore introduces less operator error in the form of angular distortion.     

The calcuLatoR—software for evaluation of evidence value of continuous type data

The role of the forensic chemist can be to evaluate physicochemical data (evidence—E) in the context of the prosecution proposition H_p and the defence proposition H_d. From a forensic point of view, the most suitable form of evaluating the evidence value of physicochemical data is by calculation of the likelihood ratio (LR).There are many LR models which could be used for measuring the evidence value of results of analysis of glass samples. A disadvantage of these models is that there is a lack of commercially available software that is suitable for use by forensic experts, who may lack experience in programming. Therefore such users are required to write their own case specific routines, e.g. in R software (www.r-project.org).The Graphical User Interface software named “calcuLatoR” for the calculation of the LR value for univariate data (such as refractive index data) has been developed. The LR model assumes two sources of variation, i.e. between replicates within the same object (within object variability) and between replicates between various objects (between object variability). It was assumed that the within object distribution is normal with constant variance. The between object distribution was modelled by a univariate kernel density estimator, i.e. using Gaussian kernels. The calcuLatoR could also be used for evaluating the evidential value of multivariate data but it must be assumed that the considered variables are independent. In this situation, LR should be calculated for each variable separately and a final value of LR is equal to their product.Validation of the calculations performed by the calcuLatoR was carried out by comparing results obtained by routines written in R.     

CNN-Based Forensic Method on Contrast Enhancement with JPEG Post-Processing

As one of the most popular digital image manipulations, contrast enhancement (CE) is frequently applied to improve the visual quality of the forged images and conceal traces of forgery, therefore it can provide evidence of tampering when verifying the authenticity of digital images. Contrast enhancement forensics techniques have always drawn significant attention for image forensics community, although most approaches have obtained effective detection results, existing CE forensic methods exhibit poor performance when detecting enhanced images stored in the JPEG format. The detection of forgery on contrast adjustments in the presence of JPEG post processing is still a challenging task. In this paper, we propose a new CE forensic method based on convolutional neural network (CNN), which is robust to JPEG compression. The proposed network relies on a Xception-based CNN with two preprocessing strategies. Firstly,unlike the conventional CNNs which accepts the original image as its input, we feed the CNN with the gray-level co-occurrence matrix (GLCM) of image which contains CE fingerprints, then the constrained convolutional layer is used to extract high-frequency details in GLCMs under JPEG compression, finally the output of the constrained convolutional layer becomes the input of Xception to extract multiple features for further classification. Experimental results show that the proposed detector achieves the best performance for CE forensics under JPEG post-processing compared with the existing methods.     

红外光谱成像技术检测纺织品上的轮胎痕迹

目的：研究一种显现和提取纺织品上潜在轮胎痕迹的光学方法。方法：利用红外成像光谱仪采集被检纺织品的光谱影像集,并运用去混合（Unmix）方法对光谱影像集进行分析和处理。结果：在被检纺织品上显现了清晰的轮胎痕迹。结论：红外光谱成像技术是检测纺织品上潜在轮胎痕迹的有效光学方法。     

LATENT IMAGES ON THE CAMERA’S WALL: Forensic aesthetics as photography

This paper examines the “algorithmic turn” in light of the “forensic turn” and seeks to consider the relevance of Forensic Architecture’s work for the theory of photography. First, I will analyze the role of photography as testimony in light of the concept of “forensic aesthetics,” and argue that with it, the role of photography as evidence is less related to its visible dimensions and more to its being a material trace—an invisible latent image that needs to be developed and animated. Second, I will diagnose the implication of the concept of “forensic aesthetics” in one of the agency’s first research projects: an investigation of US drone warfare in Pakistan from 2011 and argue that the concern that arose with the emergence of digital photography from a “post-photographic” era—in which the effect of digital technologies was perceived as the virtualization of the world—takes a material twist with forensic aesthetics. It is precisely the digitization of photography that enables it to maintain its indexical power, even at the cost of losing its limits as a medium.