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。     

视频图像处理技术的原理及智能化发展

<正>图像是人类获取信息、表达信息和传递信息的重要手段,自从数字图像诞生以后,图像就逐步成为了人类获取信息的主要形式之一。如今,观看在线视频、视频会议、视频通话、手机拍照、扫描仪扫描文件已经成为我们日常工作生活的一部分,这些都涉及到与视频图像打交道。随着大数据时代的来临,视频图像数据也在海量产生,视频图像处理技术的研究和应用也开始向智能化的方向发展。     

刑事数字图像增强、复原处理一般方法初论

通过一些实例讨论了包括图像问题分析与评估、图像降噪处理、增强图像细节、干扰背景去除、模糊图像复原与监控录像重建的基本方法,总结并给出一些典型的刑事数字图像增强和复原处理的一般方法及其处理策略。     

用Photoshop软件制作全景照片

在现场照相中常用到回转连续拍照法和直线连续拍照法。然后,在正片的后期制作中利用传统的拼接方法制作全景照片,程序繁琐难度大,效果也得不到保证。而采用计算机和相应的图像处理软件来制作,则可以轻而易举地做到“天衣无缝”。根据笔者实际操作情况,现将利用Photoshop7·0制作全景照片的方法,介绍如下:(1)将用回转连续拍照法或直线连续拍照法所得的负片或正片,扫描输入计算机中,分辨率设置不小于300像素/英寸。例如:输入计算机三幅图像,分别为图像1、图像2、图像3。当然,用于制作全景照片的源照片,相互间应该有20%左右的重叠。如果重叠过…     

X线数字图像法推断前臂骨折形成时间

目的利用X线数字图像法推断前臂骨折形成的时间。方法收集70例前臂骨折患者随访的620张X线数字图像,根据X线检查骨折愈合评判标准列表,将骨折愈合过程分为5级,利用Photoshop的图像处理和测量功能,对不同年龄组、不同治疗方式的患者骨折愈合过程相关放射学标志进行观察和测量,运用SPSS11.5软件对各级愈合时间进行分析。结果年龄和手术与否分别是影响骨折愈合的独立因素,根据不同年龄、不同治疗方式可以得到各级愈合时间列表。以愈合Ⅲ级的出现时间为例,青年组采用石膏固定治疗的,平均时间为12.2周,采用手术治疗的,需要18周,而少年组采用石膏固定治疗的,则只需5.8周。结论根据骨折愈合过程中X线数字图像指标,对患者进行分组观察,可提高推断骨折形成时间的准确度。     

基于证据发现的数字图像司法取证问题研究

自视听资料、电子数据成为法定证据种类以来,由各种成像设备拍摄的数字图像广泛运用在司法活动的各个环节,为侦查、监督和审判提供着强有力的证据支持。受外界不确定因素的影响,数字图像在成像过程中或多或少会受到天气环境、拍摄器材及电磁等干扰,导致图像模糊或信息丢失,削弱了数字图像的证明力。基于证据发现的数字图像司法取证以寻找和发现证据为目的,由专业人员通过专业方法和专业设备,对数字图像进行增强和复原,突出图像的证据特征,确保数字图像的证据功能得到充分发挥。     

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。     

柱体表面指印展平的方法

物证鉴定工作中经常遇见在柱体表面附着的痕迹，主要是指印，常难于拍照，特别是难于在拍照后对图像进行精确校正，使得技术员面对很多柱面图像要么放弃拍照，要么拍照后不进行展平就直接使用，很大程度影响到使用效果。     

异烟酸-吡唑啉酮色阶法分析生物检材样品中的氰化物

目的建立生物检材样品中氰化物定性半定量法——异烟酸一吡唑啉酮色阶法,以适应基层工作的需要。方法采用蒸馏法完成生物检材样品的净化、提取,吸收液中的氰化物在中性pH6．8～pH7．0溶液中,与氯胺T作用生成氯化氰。再与异烟酸-吡啉唑酮作用生成蓝色络合物。结果通过目视比较样品管与标准色阶管的颜色,可判断样品中氰化物的含量范围。结论本方法易操作、抗干扰性强、适合基层实验室参考使用。     

压痕文字显现1例

某日，笔者检验了一起压痕字迹案件，该压痕文字是书写工具在１６开信笺纸上书写时，受到外力作用留下的凹陷字痕。压痕较浅，布满全篇，除纸颜色稍发黄外，纸张较平滑，折皱痕较少。检测方法主要采用专业数码相机单侧，二次配光拍照，计算机图像处理，并通过彩色喷墨打印机打印保存结果。具体过程如下：将柯达６２０专业数码相机固定在三角架上，８W日光灯加上一个用硬纸板制成的遮光灯罩，以不大于１５度的入射角进行照射拍照，再根据二次配光原理配光进行拍照。用数码相机摄入图像以６００DPI分辨率传输到计算机中，利用痕检／文检图像…     

Using JPEG quantization tables to identify imagery processed by software

The quantization tables used for JPEG compression can also be used to help separate images that have been processed by software from those that have not. This loose classification is sufficient to greatly reduce the number of images an examiner must consider during an investigation. As illicit imagery prosecutions depend on the authenticity of the images involved, this capability is an advantage for forensic examiners. This paper explains how quantization tables work, how they can be used for image source identification, and the implications for computer forensics.     

Dental age estimation through volume matching of teeth imaged by cone-beam CT

A custom-made voxel counting software for calculating the ratio between pulp canal versus tooth volume based on cone-beam CT tooth images was developed and evaluated. The aim of this study was to attempt establishing a correlation between the chronological age of a certain individual and the pulp/tooth volume ratio of one of the teeth. Twenty-eight single rooted teeth of 19 individuals with well-known chronological age were scanned by the cone-beam CT (3D Accuitomo, J. Morita, Kyoto, Japan). Next the images were analyzed using the custom-made software. Linear regression analysis was performed. The results of the analysis showed a moderate correlation between the pulp/tooth volume ratio and biological age with a coefficient of determination (R2) of 0.29. Although the present work was limited to a pilot study, the developed technique showed promising results for dental age estimation in a non-invasive manner using cone-beam CT images in living individuals.     

Enhancing security of fingerprints through contextual biometric watermarking

This paper presents a novel digital watermarking technique using face and demographic text data as multiple watermarks for verifying the chain of custody and protecting the integrity of a fingerprint image. The watermarks are embedded in selected texture regions of a fingerprint image using discrete wavelet transform. Experimental results show that modifications in these locations are visually imperceptible and maintain the minutiae details. The integrity of the fingerprint image is verified through the high matching scores obtained from an automatic fingerprint identification system. There is also a high degree of visual correlation between the embedded images, and the extracted images from the watermarked fingerprint. The degree of similarity is computed using pixel-based metrics and human visual system metrics. The results also show that the proposed watermarked fingerprint and the extracted images are resilient to common attacks such as compression, filtering, and noise.     

三种方法计算气胸CT影像的肺萎陷程度比较

目的探讨临床经验法、手工边界勾画法和软件自动分析法在基于CT影像的气胸致肺萎陷程度计算上的优劣,从而推荐一种客观科学高效的肺萎陷程度计算方法。方法通过三种方法分别计算54例气胸患者的肺萎陷百分比,比较三种方法在计算效率、结果的相关性、准确性、稳定性等方面的差异。结果临床经验法、软件自动分析法与目前公认的手工边界勾画法的结果间存在线性相关(P<0.01),软件自动分析法的准确性更高;在5级及3级分类法中,三种方法之间存在显著一致性,软件自动分析法与手工边界勾画法在百分比判定上的一致性更好;单侧气胸的肺萎陷百分比的一致率高于双侧气胸;同时,软件自动分析法在计算结果的高效性、稳定性等方面具有优势。结论软件自动分析法可以解决现有CT影像的肺萎陷程度计算方法中效率低和稳定性欠佳的问题,且具有准确性高、可操作性强的特点,适合在法医临床实践中广泛应用。     

Discriminating natural images and computer generated graphics based on the impact of CFA interpolation on the correlation of PRNU

To discriminate natural images from computer generated graphics, a novel identification method based on the features of the impact of color filter array (CFA) interpolation on the local correlation of photo response non-uniformity noise (PRNU) is proposed. As CFA interpolation generally exists in the generation of natural images and it imposes influence on the local correlation of PRNU, the differences between the PRNU correlations of natural images and those of computer generated graphics are investigated. Nine dimensions of histogram features are extracted from the local variance histograms of PRNU to represent the identification features. The discrimination is accomplished by using a support vector machine (SVM) classifier. Experimental results and analysis show that it can achieve an average identification accuracy of 99.43%, and it is robust against scaling, JPEG compression, rotation and additive noise. Thus, it has great potential to be used in image source pipelines forensics.     

Non-destructive testing techniques for the forensic engineering investigation of reinforced concrete buildings

This study describes in detail the results of a laboratory investigation where the compressive strength of 150mm side-length cubes was evaluated. Non-destructive testing (NDT) was carried out using ultrasonic pulse velocity (UPV) and impact rebound hammer (IRH) techniques to establish a correlation with the compressive strengths of compression tests. To adapt the Schmidt hammer apparatus and the ultrasonic pulse velocity tester to the type of concrete used in Algeria, concrete mix proportions that are recommended by the Algerian code were chosen. The resulting correlation curve for each test is obtained by changing the level of compaction, water/cement ratio and concrete age of specimens. Unlike other works, the research highlights the significant effect of formwork material on surface hardness of concrete where two different mould materials for specimens were used (plastic and wood). A combined method for the above two tests, reveals an improvement in the strength estimation of concrete. The latter shows more improvement by including the concrete density. The resulting calibration curves for strength estimation were compared with others from previous published literature.     

THEMIS紫外光谱成像仪的放大率估计及其图像的长宽比校正

目的 校正THEMIS紫外光谱成像仪图像的长宽比并估计系统放大率参数.方法 制作测试图片,用紫外光谱成像仪拍摄紫外光谱影像集,由图像和测试图片的差异分析出成像缺陷和放大率参数.结果 通过Photoshop测量像素值的方法测量出图像的长宽比差异,并用MATLAB算法校正,同时得出紫外光谱成像仪的放大倍率β.结论 校正后紫外光谱图像恢复了原始比例,且系统放大率β可以在恢复痕迹原始大小时发挥作用,由此获得准确的紫外光谱图像供后续光谱分析检验和研究.     

LAB图像处理模式区分黑色圆珠笔字迹的方法验证

目的考察验证LAB模式区分黑色圆珠笔字迹的方法,以及油墨浓淡对检验结果的影响。方法采用600dpi分辨率扫描样品并将图像保存成tiff格式,运用PhotoshopCS3图像处理软件中Lab模式进行处理。结果Lab模式无损区分黑色圆珠笔字迹的识别率达到61．67％,且油墨浓淡对实验结果影响不明显。结论此方法可用于黑色圆珠笔字迹的区分检验。     

Virtual forensic anthropology: Novel applications of anthropometry and technology in a child death case

Full-body 3D virtual reconstructions were generated using 3D technology and anthropometry following the death of a young girl, allegedly from severe malnutrition as a result of abuse and neglect. Close range laser scanning, in conjunction with full colour digital texture photography, was used to document the child's condition shortly after death in order to demonstrate the number and pattern of injuries and to be able to demonstrate her condition forensically. Full-body digital reconstructions were undertaken to illustrate the extent of the malnutrition by comparing the processed post mortem scans with reconstructed images at normal weight for height and age. This is the first known instance of such an investigative tool.     

Background correction in forensic photography. I. Photography of blood under conditions of non-uniform illumination or variable substrate color--theoretical aspects and proof of concept

The combination of photographs taken at two or three wavelengths at and bracketing an absorbance peak indicative of a particular compound can lead to an image with enhanced visualization of the compound. This procedure works best for compounds with absorbance bands that are narrow compared with "average" chromophores. If necessary, the photographs can be taken with different exposure times to ensure that sufficient light from the substrate is detected at all three wavelengths. The combination of images is readily performed if the images are obtained with a digital camera and are then processed using an image processing program. Best results are obtained if linear images at the peak maximum, at a slightly shorter wavelength, and at a slightly longer wavelength are used. However, acceptable results can also be obtained under many conditions if non-linear photographs are used or if only two wavelengths (one of which is at the peak maximum) are combined. These latter conditions are more achievable by many "mid-range" digital cameras. Wavelength selection can either be by controlling the illumination (e.g., by using an alternate light source) or by use of narrow bandpass filters. The technique is illustrated using blood as the target analyte, using bands of light centered at 395, 415, and 435 nm. The extension of the method to detection of blood by fluorescence quenching is also described.