Digital camera identification using PRNU: A feature based approach

Source camera identification is one of the emerging field in digital image forensics, which aims at identifying the source camera used for capturing the given image. The technique uses photo response non-uniformity (PRNU) noise as a camera fingerprint, as it is found to be one of the unique characteristic which is capable of distinguishing the images even if they are captured from similar cameras. Most of the existing PRNU based approaches are very sensitive to the random noise components existing in the estimated PRNU, and also they are not robust when some simple manipulations are performed on the images. Hence a new feature based approach of PRNU is proposed for the source camera identification by choosing the features which are robust for image manipulations. The PRNU noise is extracted from the images using wavelet based denoising method and is represented by higher order wavelet statistics (HOWS), which are invariant features for image manipulations and geometric variations. The features are fed to support vector machine classifiers to identify the originating source camera for the given image and the results have been verified by performing ten-fold cross validation technique. The experiments have been carried out using the images captured from various cell phone cameras and it demonstrated that the proposed algorithm is capable of identifying the source camera of the given image with good accuracy. The developed technique can be used for differentiating the images, even if they are captured from similar cameras, which belongs to same make and model. The analysis have also showed that the proposed technique remains robust even if the images are subjected to simple manipulations or geometric variations.     

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.     

Ear identification: a pilot study

Although several papers have recently been devoted to establishing the validity of identification using the ear, this part of the human body still remains underexploited in forensic science. The perfect overlap of two images of the same ear is not really possible, but photographs of the ears as a reliable means of inferring the identity of an individual are poorly treated in the literature. In this study, we illustrate a simple, reproducible method, which divides the photograph of an ear into four parts-helix, antihelix, concha, and lobe-by means of a suitable grid of four straight lines. Although the division does not follow exact anatomical features, their edges do join anatomical points which are more easily identifiable. Measurement of certain areas of these parts can be combined to produce a code allowing personal identification. This method produces false-positive identifications of <0.2%. Last, the repeatability and reproducibility aspects of the method are tested.     

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.     

Dental identification using digital images via computer network

Dental identification is a useful scientific method. In Japan, however, there are only a few forensic odontologists; moreover, until now, forensic dental services have only been offered by general dentists. These dentists may not be able to offer such forensic services during office time. For a quick comparison, the authors tried sending digital photos, taken with a 2-million-pixel digital camera, to dental offices via the Internet. If a dental office has Internet access, it is possible for dental charting to be sent directly to the autopsy room. Of course, digital images only provide the first outline. However, when antemortem dental records of the person in question are available at autopsy, a quick comparison can be made.     

Using anisotropic diffusion for efficient extraction of sensor noise in camera identification

Each digital camera has an intrinsic fingerprint that is unique to each camera. This device fingerprint can be extracted from an image and can be compared with a reference device fingerprint to determine the device origin. The complexity of the filters proposed to accomplish this is increasing. In this note, we use a relatively simple algorithm to extract the sensor noise from images. It has the advantages of being easy to implement and parallelize, and working faster than the wavelet filter that is common for this application. In addition, we compare the performance with a simple median filter and assess whether a previously proposed fingerprint enhancement technique improves results. Experiments are performed on approximately 7500 images originating from 69 cameras, and the results are compared with this often used wavelet filter. Despite the simplicity of the proposed method, the performance exceeds the common wavelet filter and reduces the time needed for the extraction.     

Ear piercing affects earprints: the role of ear piercing in human identification

Previous research conducted into the use of the human ear in the field of forensic identification has focused upon the use of grids and manual methods to measure and catalogue the different anatomical features of the ear. To date, few have considered the importance of the presence of ear piercings and their possible role in human identification. This study aims to highlight the common distribution of piercings of both ears in both genders and to explore the effect of piercings on earprints. The presence of a piercing may, in part, help to explain why partial and not whole earprints are sometimes recovered from a scene of crime (suggesting that the offender's ears may be pierced). The presence of piercings through the tragus and the superior part of the helix are shown to be infrequent and thus may be used to assist the identification of a body, due to its relative rarity with respect to piercings found in other areas of the ear.     

运用局部形态SIFT描述法过滤网络淫秽图像方法的研究

各国政府和警方目前使用的传统淫秽图像检测方法主要以皮肤检测结果为基础,提取低层特征进行判断,在获得高正检率的同时也导致了大量的误检。为此,本文的方法从获得更直观和高层的语义知识着手,首先检测图像中局部形态变化突出的位置,并建立关于该区域形态的SIFT描述向量。把这些描述向量抽象地看作视觉“单词”,并收集淫秽图像中常见的单词。依据图像中单词出现的情况,来检测是否包含淫秽成分。结合传统检测方法,仅使用简单的Bayes规则判断,在不降低正检率的前提下,使非淫秽图像的误检率得到显著的下降。     

Application of superimposition-based personal identification using skull computed tomography images

Superimposition has been applied to skulls of unidentified skeletonized corpses as a personal identification method. The current method involves layering of a skull and a facial image of a suspected person and thus requires a real skeletonized skull. In this study, we scanned skulls of skeletonized corpses by computed tomography (CT), reconstructed three-dimensional (3D) images of skulls from the CT images, and superimposed the 3D images with facial images of the corresponding persons taken in their lives. Superimposition using 3D-reconstructed skull images demonstrated, as did superimposition using real skulls, an adequate degree of morphological consistency between the 3D-reconstructed skulls and persons in the facial images. Three-dimensional skull images reconstructed from CT images can be saved as data files and the use of these images in superimposition is effective for personal identification of unidentified bodies.     

Personal identification based on radiographic vertebral features

Personal identification of human remains constitutes about 10% of the normal caseload of any forensic medicine practice. Identification can be achieved by a variety of methods, one of which is the comparison of antemortem and postmortem radiographs. There are numerous accounts of cranial and dental radiographic features useful for identification, whereas the availability of postcranial radiographs and especially plates that depict the vertebral column is less widespread among the forensic community. The authors here review the various vertebral features instrumental in positive identification that can be identified on radiographs of the spine.     

Sentence identification system based on criminal law ontology

In this research, an identification system is proposed for the benefit of determining a possible sentence and retrieving the related cases under criminal law codes of Thailand. The system is based on the developed criminal law ontology for the advantage of structuralizing and semanticizing in selected articles. From the underlying legal elements described in law codes textually, the ontology shall provide the determination of possible sentences which consist of judgment and theoretically figured range of punishments. An application has been designed and demonstrated in two consequential modules: the legal elements identification and the sentence identification. The developed ontology and its extended web application will be shown and illustrated as a sequential flow and evaluated by the legal experts and the end-users. The evaluation results showed that the averaged satisfactions for both groups of experts and end-users were 89% and 84%, respectively.     

Postmarket surveillance. Final rule

The Food and Drug Administration (FDA) is implementing the postmarket surveillance (PS) provisions of the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Food and Drug Administration Modernization Act of 1997 (FDAMA). The purpose of this rule is to provide for the collection of useful data about devices that can reveal unforeseen adverse events or other information necessary to protect the public health.     

Assessment of approximate likelihood ratios from continuous distributions: a case study of digital camera identification

A reported likelihood ratio for the value of evidence is very often a point estimate based on various types of reference data. When presented in court, such frequentist likelihood ratio gets a higher scientific value if it is accompanied by an error bound. This becomes particularly important when the magnitude of the likelihood ratio is modest and thus is giving less support for the forwarded proposition. Here, we investigate methods for error bound estimation for the specific case of digital camera identification. The underlying probability distributions are continuous and previously proposed models for those are used, but the derived methodology is otherwise general. Both asymptotic and resampling distributions are applied in combination with different types of point estimators. The results show that resampling is preferable for assessment based on asymptotic distributions. Further, assessment of parametric estimators is superior to evaluation of kernel estimators when background data are limited.     

Forensic identification value of roentgen images in determining tooth-colored dental filling materials]

Identification of unknown bodies is mainly made by dental examination and comparison with accurate dental records. Therefore it is necessary to examine the jaws carefully and to locate every tooth-coloured dental restoration. Overlooking dental fillings can make positive identification impossible. The paper presented here evaluates the usefulness of radiographs to locate tooth coloured dental restorations. RESULTS: 40% of the dental materials tested here could not be detected radiographically with a sensitivity that is demanded. A radiographic examination is not sufficient and must be supplied by other techniques.     

PRNU based source camera attribution for image sets anonymized with patch-match algorithm

Patch-Match is an efficient algorithm used for structural image editing and available as a tool on popular commercial photo-editing software. The tool allows users to insert or remove objects from photos using information from similar scene content. Recently, a modified version of this algorithm was proposed as a counter-measure against Photo-Response Non-Uniformity (PRNU) based Source Camera Identification (SCI). The algorithm can provide anonymity at a great rate (97%) and impede PRNU based SCI without the need of any other information, hence leaving no-known recourse for the PRNU-based SCI. In this paper, we propose a method to identify sources of the Patch-Match-applied images by using randomized subsets of images and the traditional PRNU based SCI methods. We evaluate the proposed method on two forensics scenarios in which an adversary makes use of the Patch-Match algorithm and distorts the PRNU noise pattern in the incriminating images she took with his camera. Our results show that it is possible to link sets of Patch-Match-applied images back to their source camera even in the presence of images that come from unknown cameras. To our best knowledge, the proposed method represents the very first counter-measure against the usage of Patch-Match in the digital forensics literature.     

Post-mortem radiological CT identification based on classical ante-mortem X-ray examinations

Radiological identification is important in forensic medicine. Identification using comparison of individualising structures with ante- and post-mortem conventional radiographs has been known for a long time. New radiological procedures such as computed tomography (CT) and magnetic resonance imaging (MRI) are being increasingly used for identification. In this paper, a new comparative approach using various radiological methods is described and its application demonstrated. This new approach is the comparison of ante-mortem conventional radiographs with projected images calculated from post-mortem CT data. The identification procedure will be illustrated with reference to the frontal sinus and the pelvis.     

Personality identification based on the outcomes of mass casualty events

This study concerns the problem of personality identification based on the outcomes of mass casualty events. New organizational measures are proposed to optimize the work with cadaveric materials. Specifically, they envisage creation of four major working groups and organization of their cooperation along the following lines: collection and delivery of postmortem information, systematization of antemortal information, and functioning of the identification centre. DNA-technologies and computer-assisted data processing are shown to find the increasingly wider application for personality identification.     

Rationale of identification based on biological factors of the dentition

Dental traits in the nature of form and size of fissures, cusps, and pits often reflect genetic and phylogenetic interactions in growth and development that are common to other individuals and serve a useful purpose in identification.     

根据股骨组织形态学变化进行骨骼种属鉴别

目的通过对成年人、成体黄牛、马、家猪、山羊、绵羊、狗、猫、长毛兔、鹅、鸭、鸡共12个种属动物股骨组织形态学结构特征的研究,建立一个有效的各类动物间种属鉴别的方法。方法在征得家属同意后,在尸检中取成人(20岁以上)右股骨中段约4cm,同时,收集黄牛、马、家猪、山羊、绵羊、狗、猫、长毛兔、鹅、鸭、鸡共11种常见动物右腿股骨,取中段约4cm,脱钙后制作成骨组织切片,在光学显微镜下观察,将显微镜下的图像录入电脑,选取24个指标进行分析。结果人与其他动物、以及各被检动物之间在骨单位数量等13个指标上具有显著差异,用这些指标建立种属判别数学模型,结果这些动物之间的判别率也可达89.4%。结论股骨中段骨密质的组织学结构具有明显的种属特征,且骨单位形态和数量呈现明显的生物进化趋势。根据这些特征可以有效地进行种属鉴别。