DCS-3数字化手印提取处理系统的应用

当前数码相机应用于刑事照相日渐普及，对于所得图像的后期处理也就越来越多，提取了如指印、足迹等痕迹后，大家都习惯使用Adobe Photoshop处理，以前也有文章介绍过。但Adobe Photoshop不是专门针对提高法庭图像的使用率而开发的。最近本单位引进的DCS-3数字化手印提取处理系统，可以方便地提取指印等痕迹并对所得图像进行处理。该系统以根据英国权威机构HOME OFFICE POLICE SCIENFITIC DEVELOPMENT BRANCH（简称PSDB）颁布的手印显现技术手册为基础，将手印的显现技术、图像处理技术、光学照相融为一体，为用户提供全套的手印提取、增强处理、输出，从硬件到软件的全套解决方案。本文介绍DCS-3数字化手印提取处理系统去除指印的干扰背景的几个应用。     

根据头颈部生理特征鉴别伪造照片1例

1案件简介某单位委托检验照片一张,要求检验照片真伪。由于照片分辨率低下,看不到拼接痕迹,无法用一般方法进行检验,因此考虑运用人物的运动关系和生理特性进行图像检验。该照片中人物特点是,体型较胖,颈部脂肪较多。运动特征为：平躺在床上,后脑部贴靠床头垂直的墙上,造成颈部前屈。由于分辨率低下,看不到拼接痕迹,常规方法难以确定其真伪。     

视频取证技术研究进展

由于近年来多媒体采集设备和影像处理工具的普及和广泛应用,人们可以轻易对图像和视频进行篡改。利用恶意篡改的图像和视频进行敲诈勒索的案件日益增多,判断监控系统拍摄或者网上下载的图像和视频的原始性和真实性成了迫切需要解决的问题。之前的研究工作多集中在图像取证领域,对视频取证的研究近几年刚刚开始。和图像相比,视频数据量大,数据格式复杂,存储压缩因子高,对取证算法的计算要求高;不过,由于视频在编码方式、时空特性、篡改手段上都有着鲜明的特点,视频取证有更为丰富的研究内容和更为广阔的应用前景。研究人员利用视频采集和压缩编码过程中的特性,以及篡改手段带来的痕迹,对视频篡改检测方法进行了相关探索,取得了一些成果。先前的综述文献大都集中在图像取证领域,只有少数细节涉及到视频取证分析,本文对视频取证技术进行了综述。鉴于某些图像取证技术可用于视频单帧图像取证分析,本文第一部分首先介绍了图像取证相关技术如相机参数、压缩和物理几何不一致取证等。接着对已经提出的视频取证技术,按照采集、压缩和篡改方式进行分类,对它们的原理和优缺点进行了综述,并对反取证技术的相关研究工作进行了介绍。第二部分重点介绍视频采集过程以及辨识视频采集设备的一些方法。第三部分对因编码参数、编码标准以及压缩次数等视频编码过程的不同而遗留的痕迹进行了探讨。第四部分将介绍基于检测视频采集和编码痕迹不一致的取证分析方法,以及揭示篡改遗留痕迹的方法。图像视频压缩检测取证方法的发展始终伴随着相应反取证方法的研究,因此第五部分对视频反取证方法做了介绍。视频取证已经逐渐成为一个研究热点,得到越来越多的研究和关注,仍有许多未知的领域等待更加深入的研究和探索。     

不同光照条件下静态目标图像处理方法

在模糊视频图像处理技术中，对同一序列图像内的多帧图像进行积分、融合运算，以提高分辨率、增加信息量、降低噪声是当前最有效的方法。其原理是在叠加运算中减弱随机噪声，保持目标信息的稳定性。其技术要点：一是合理挑选有效帧，二是对特定目标运动轨迹进行跟踪、稳定、配准预处理，三是选择帧平均、帧融合算法。     

浅谈数码影像在刑事技术中的应用优势

随着现代计算机信息和网络技术的高速发展，数码影像技术作为高科技数字化的结晶，对传统摄影技术和暗房技术发起了严竣挑战，其在后期影像处理方面通过与计算机网络技术有机结合，所体现出来的快捷、方便、灵活的巨大优势更是传统的影像技术所不能企及，具体在刑事技术的应用中主要体现出以下８个方面的优势：１摄取图像的直观性用数码相机拍摄照片时，相机的液晶显示屏（LCD）可同步显现图像，利用这一特点在刑事技术的现场勘查中可以即时、直观地观测到所拍现场照片的真实完整性，尤其是在拍摄现场痕迹物证时，可以通过液晶显示屏（LC…     

基于多信息融合的多车事故碰撞过程分析方法

多车事故由于发生多次碰撞导致痕迹叠加、错乱,碰撞过程分析存在较大技术困难,事故再现难以推进。介绍了基于痕迹的碰撞事故过程一般分析方法,重点针对多车碰撞事故,提出将痕迹、EDR、微量物证、视频/音频等信息要素融合的分析思路及方法,通过一起高速公路多车事故案例,进行了方法的实证分析,表明基于多信息融合的多车事故碰撞过程分析方法具有较好的实用性,有助于道路交通多车事故的碰撞过程分析,进而提升事故再现的准确性。     

数码相机拍摄指纹制作指定比例照片的方法

近年来数字技术日臻完善,已广泛应用于各个领域。数字技术的引入对传统的刑事照相产生了深刻影响。采用数码相机拍照不仅可以直接显示图像,还可保证疑难指纹拍照的成功率,加上网络的支持更使它如虎添翼。由于数码相机镜头的特殊性且不同品牌相机镜头标准不统一再加上成像分辨率的影响,所以用数码相机将指纹直接拍摄成1∶1或相同比例的照片几乎是办不到的。如何用数码相机得到所需的指定比例照片,笔者在实际工作中摸索出了一定的方法,现提出以供大家参考。Photoshop是个功能十分强大的图像处理软件,其处理图像十分方便,效果也很理想。在Phot…     

基于空间序列上图像单元集合的图像合成方法

配光检验是指通过选择照明光线入射角度和方向来调整控制检材反射光亮度分布并在垂直方向接受记录的方法。该方法在检验指印、鞋印和其他痕迹方面有着非常重要的作用,可以显现一些在普通光线下看不见的潜在痕迹,也可以加强微弱痕迹反差或减弱客体对痕迹的干扰,从而清晰地显现痕迹。在实际的检案工作中,承痕体具有不同的形状、大小和质地,痕迹物质的构成也千差万别,对光线表现出不同的吸收反射性质,很难在垂直方向上通过配光检验方法将痕迹物证的所有细节特征一次性完整拍摄下来,这样就给后期的检验鉴定带来一定的困难。随着计算机技术的飞速…     

利用扫描仪记录实物表面图像

在刑事技术工作中，现场勘查到的实物表面留有的花纹图像、手印图像、工具痕迹图像、鞋底花纹图、现场留有的花纹图像鞋印痕迹、袜印痕迹等等。记录上述这些图像通常方法是用照相机对图像花纹进行拍照，现在也常用数码照相机进行拍照记录，方法较烦琐，用起来比较麻烦，拍照、冲卷、洗印等，数码相机用起来虽然方便，但基层单位因经济条件的限制无法普及。     

刑事照相与图像数字处理技术

论述了刑事照相技术在当今信息时代的发展方向,展望了数字图像数字处理技术在刑事照相中的具体应用,讨论了刑事照片客观真实性与数字技术处理图像方便灵活性之间对立统一的关系,阐述了图像数字技术必将取代传统摄影技术而被引入到刑事照相中来的观点.     

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。     

Multi-resolution image fusion technique and its application to forensic science

Image fusion is a process of combining two or more images into an image. It can extract features from source images, and provide more information than one image can. Multi-resolution analysis plays an important role in image processing, it provides a technique to decompose an image and extract information from coarse to fine scales. In some practical forensic examinations (such as the cartridge image check), we cannot obtain all information from just one image; on the contrary, we need information from images with difference light sources (or light ways). In this paper, we apply an image fusion method based on multi-resolution analysis to forensic science. Synthetic and real images (such as images from closed-up photography and flash photography) are used to show the capability of the multi-resolution image fusion technique.     

Explosion Scene Forensic Image Interpretation

Image interpretation is an important aspect in the field of forensic science; however, it is seldom reported how to use these techniques in explosion scene forensic investigations. On 12 August 2015, a series of explosions killed 165 people and injured hundreds more at a container storage station at the Port of Tianjin. In this study, we applied image interpretation methods to determine the seat of the explosion by analyzing low‐quality video clips of the event. The interpretation fits well with recently published standard operating procedures, including the hypothesis, evaluation, inference, and confirmation. Image processing was adopted to enhance the images while the explosion scene was reconstructed with the same images. Some important features were extracted and utilized to distinguish whether the flashes were caused by reflection or a real blast. We reveal the real explosion location, which guides the overall investigation. The results indicate that image interpretation is a powerful tool for forensic investigators to analyze low‐quality images in complicated explosions or fire accidents.     

Photographic Image Comparison of Vegetation

Images and videos are common types of evidence in crime scene investigations and laboratory analysis. Images may be taken by the suspect and/or by crime scene investigators and may serve as crucial elements in forensic laboratory analysis. Forensic photographic image comparison is the process of comparing one or more objects or persons in photographs/images when at least one image is known to be related to a crime. The forensic examiner usually compares the images in order to determine whether or not an association between the exhibits in the images can be made. This paper proposes an extension to the currently prevalent photographic image examination method. The extension introduces comparison of landscape and vegetation over time. It is revealed that similarities between images may still be found between the period of time the suspect photograph was taken and the period the crime scene investigator took the photograph from the same area. In this case report, two suspects to be involved in growing a marijuana field were arrested by the police. The forensic experts were asked to examine images taken by the crime scene investigators and to compare them to the images found in the suspects’ phones. They then tried to determine whether the suspects could be linked to the specific locations. While applying techniques derived from morphological comparison methodologies, the plants at the scene provided significant additional information. A tree trunk, branches, and twigs on a hedge in the photographs revealed specific individual characteristics that led the examiner to reach a conclusive decision.     

数字图像技术辅助二次短路熔痕金相组织定量分析研究

以电气火灾二次短路熔痕显微组织为例，利用显微图像各组元的灰度特性，运用数字图像技术中的图像滤波、图像分割、轮廓提取方法对显微组织图像进行预处理，获取图像晶格和孔洞。结合体视学方法．对显微组织晶格粒径、孔洞大小等几何特征参数进行计算分析与测量，探讨数字图像技术辅助二次短路熔痕金相组织进行定量分析技术方法。     

Multi-resolution image fusion technique and its application to forensic science

Image fusion is a process of combining two or more images into an image. It can extract features from source images, and provide more information than one image can. Multi-resolution analysis plays an important role in image processing, it provides a technique to decompose an image and extract information from coarse to fine scales. In some practical forensic examinations (such as the cartridge image check), we cannot obtain all information from just one image; on the contrary, we need information from images with difference light sources (or light ways). In this paper, we apply an image fusion method based on multi-resolution analysis to forensic science. Synthetic and real images (such as images from closed-up photography and flash photography) are used to show the capability of the multi-resolution image fusion technique.     

The Effects of High Dynamic Range on Fingerprint Images Processed by Photoshop

High dynamic range (HDR) imaging is a function that combines five images with different exposures into a single image. This technique may provide fine ridge details of fingerprint images for forensic latent fingerprint examination. Therefore, viewing fingerprints under optimal conditions is of paramount importance. This paper analyzes HDR and non‐HDR photos by using the Michelson contrast formula. The Michelson formula will provide a measurement to determine whether better contrast between the background and print can be achieved using the HDR function and if the background color affects the quality of the images. Two hypothesis were tested: (i) the HDR image provides more details of fingerprints with a better tone, greater clarity, and contrast than a normally exposed image regardless of the background color; (ii) the background color does not affect the quality of HDR fingerprint images overall, but the multi‐color background may increase the contrast of HDR fingerprint images in some cases.     

A Novel Method for the Photographic Recovery of Fingermark Impressions from Ammunition Cases Using Digital Imaging

The photographic preservation of fingermark impression evidence found on ammunition cases remains problematic due to the cylindrical shape of the deposition substrate preventing complete capture of the impression in a single image. A novel method was developed for the photographic recovery of fingermarks from curved surfaces using digital imaging. The process involves the digital construction of a complete impression image made from several different images captured from multiple camera perspectives. Fingermark impressions deposited onto 9‐mm and 0.22‐caliber brass cartridge cases and a plastic 12‐gauge shotgun shell were tested using various image parameters, including digital stitching method, number of images per 360° rotation of shell, image cropping, and overlap. The results suggest that this method may be successfully used to recover fingermark impression evidence from the surfaces of ammunition cases or other similar cylindrical surfaces.     

A local variance based approach to alleviate the scene content interference for source camera identification

Identifying the source camera of images is becoming increasingly important nowadays. A popular approach is to use a type of pattern noise called photo-response non-uniformity (PRNU). The noise of image contains the patterns which can be used as a fingerprint. Despite that, the PRNU-based approach is sensitive towards scene content and image intensity. The identification is poor in areas having low or saturated intensity, or in areas with complicated texture. The reliability of different regions is difficult to model in that it depends on the interaction of scene content and the characteristics of the denoising filter used to extract the noise. In this paper, we showed that the local variance of the noise residual can measure the reliability of the pixel for PRNU-based source camera identification. Hence, we proposed to use local variance to characterize the severeness of the scene content artifacts. The local variance is then incorporated to the general matched filter and peak to correlation energy (PCE) detector to provide an optimal framework for signal detection. The proposed method is tested against several state-of-art methods. The experimental results show that the local variance based approach outperformed other state-of-the-art methods in terms of identification accuracy.     

图像降噪和增强对人脸识别系统识别性能的影响

目的研究图像降噪和图像增强方法对人脸识别系统识别性能的影响,以期为人脸识别系统应用过程中的图像处理方法选取提供理论指导和技术方案。方法收集33起人像鉴定领域实际案例中的人脸图像素材,研究以高斯滤波和小波变换为代表的图像降噪技术以及具有边缘保持和小波变换特性的单帧图像超分辨率增强技术对人脸识别系统识别性能的影响,并对不同图像处理方法对人脸识别性能的影响进行量化比较分析。结果本文研究的图像降噪技术均显著提高了人脸识别系统的识别准确性,而图像增强技术虽然提高了人脸图像显示效果,但对人脸识别系统的识别性能无正向促进作用。此外,高斯模糊图像处理的图像降噪方法虽然简单,但与本文研究的其他方法比较,其在人脸识别系统识别性能改善方面效果最显著。结论人脸图像质量对人脸识别系统的识别性能具有显著影响,可以通过图像处理技术改善人脸图像质量进而提高人脸识别系统的识别准确性。其中,图像降噪处理可以显著提高人脸识别系统的识别性能,且比图像增强技术更适合于实际人像鉴定应用中的人脸识别系统识别性能增强。