Over the past few years, both large multinationals and governments have begun to contribute to even larger projects on biometric devices. Terrorist attacks in America and in other countries have highlighted the need for better identification systems for people as well as improved systems for controlling access to buildings. Another reason for investment in Research and Development in Biometric Devices, is the massive growth in internet-based systems -- whether for e-commerce, e-government or internal processes within organizations. The interface between the system and the user is routinely abused, as people have to remember many complex passwords and handle tokens of various types. In this paper an overview is given of the information that is important to know before an examination of such is systems can be done in a forensic proper way. In forensic evidence with biometric devices the forensic examiner should consider the possibilities of tampering with the biometric systems or the possibilities of unauthorized access before drawing conclusions.
The gait parameters of eleven subjects were evaluated to provide data for recognition purposes of subjects. Video images of these subjects were acquired in frontal, transversal, and sagittal (a plane parallel to the median of the body) view. The subjects walked by at their usual walking speed. The measured parameters were hip, knee and ankle joint angle and their time averaged values, thigh, foot and trunk angle, step length and width, cycle time and walking speed. Correlation coefficients within and between subjects for the hip, knee and ankle rotation pattern in the sagittal aspect and for the trunk rotation pattern in the transversal aspect were almost similar. (were similar or were almost identical) This implies that the intra and inter individual variance were equal. Therefore, these gait parameters could not distinguish between subjects. A simple ANOVA with a follow-up test was used to detect significant differences for the mean hip, knee and ankle joint angle, thigh angle, step length, step width, walking speed, cycle time and foot angle. The number of significant differences between subjects defined the usefulness of the gait parameter. The parameter with the most significant difference between subjects was the foot angle (64 % - 73 % of the maximal attainable significant differences), followed by the time average hip joint angle (58 %) and the step length (45 %). The other parameters scored less than 25 %, which is poor for recognition purposes. The use of gait for identification purposes it not yet possible based on this research.
Forensic Image Databases appear in a wide variety. The oldest computer database is with fingerprints. Other examples of databases are shoeprints, handwriting, cartridge cases, toolmarks drugs tablets and faces. In these databases searches are conducted on shape, color and other forensic features. There exist a wide variety of methods for searching in images in these databases. The result will be a list of candidates that should be compared manually. The challenge in forensic science is to combine the information acquired. The combination of the shape of a partial shoe print with information on a cartridge case can result in stronger evidence. It is expected that searching in the combination of these databases with other databases (e.g. network traffic information) more crimes will be solved. Searching in image databases is still difficult, as we can see in databases of faces. Due to lighting conditions and altering of the face by aging, it is nearly impossible to find a right face from a database of one million faces in top position by a image searching method, without using other information. The methods for data mining in images in databases (e.g. MPEG-7 framework) are discussed, and the expectations of future developments are presented in this study.
We have reported the Charge Coupled Device (CCD) fingerprint method for identification of digital still cameras. The CCD fingerprint method utilizes the nonhomogeneous nature of dark currents in CCDs. In this study, we have measured CCD defects patterns of various digital still cameras including professional cameras and cheap ones with various resolution and compression rates. As a result, CCD defect pattern was detected in all cameras except for a low-resolution cheap camera using only one image. Resolution mode change of digital cameras did not affect the position of defect points in general but in some cases, relative pixel intensity varied. Image compression did not affect the pixel position for blank images within normal compression rate, but when there existed light in the background, the pixel position was blurred as the compression rate became high. In conclusion, it is recognized that the CCD fingerprint method can be applied in principle to digital still cameras, that is, individual camera identification can be achieved in principle by using images taken with the camera.
In this research an evaluation has been made of the different ways of contents based image retrieval of logos of drug tablets. On a database of 432 illicitly produced tablets (mostly containing MDMA), we have compared different retrieval methods. Two of these methods were available from commercial packages, QBIC and Imatch, where the implementation of the contents based image retrieval methods are not exactly known. We compared the results for this database with the MPEG-7 shape comparison methods, which are the contour-shape, bounding box and region-based shape methods. In addition, we have tested the log polar method that is available from our own research.
From the court we were asked whether it is possible to determine if an image has been made with a specific digital camera. This question has to be answered in child pornography cases, where evidence is needed that a certain picture has been made with a specific camera. We have looked into different methods of examining the cameras to determine if a specific image has been made with a camera: defects in CCDs, file formats that are used, noise introduced by the pixel arrays and watermarking in images used by the camera manufacturer.
On the market several systems exist for collecting spent ammunition data for forensic investigations. These databases store images of cartridge cases and the marks on them. Image matching is used to create hit lists that show those cartridges in the database which have marks that are most similar to the marks of the cartridge case under investigation. The research in this paper focuses on the different methods of feature selection and pattern recognition that can be used for optimizing the results of image matching. A fast pre-selection method based on signatures is applied that is based on the Kanade Lucas Tomasi equation. The positions of the points compared with this method are compared. In this way 11 of the 49 images were in the top position in combination with the third scale of the a trous wavelet. Light conditions and the prominence of the marks determines to a large extent whether correct matches are found in the top ranked position. All images were retrieved in the top give percent of the complete database. This method takes only a few minutes, which can be structured for comparisons to be carried out in seconds.
We use an automatic re-registering of frames taken from a surveillance video to improve signal-to-noise in regions of particular interest. A wavelet transform with automatic signal and noise estimation is used for this purpose. We describe the results obtained using a short surveillance video sequence.
In this paper, we present some results from a study in progress on methods for the measurement of the length of a robber in a surveillance video image. A calibration tool was constructed for the calibration of the camera. Standard procedures for computing the lens distortion, image projection parameters and the length of the robber have been implemented in Mathematika. These procedures are based on the use of pixel coordinates of markers on the calibration tool, the robber's head (and, optionally, his feet) and an estimation of his position in the coordinate system that is defined by the calibration tool.
In this paper, we describe the use and processing of image sequences for forensic investigations. For real-time digitization and storage of uncompressed movie files we use a computer equipped with a disk array system. The number of tape playbacks is minimized, while the use of still image/pause options of the VCR can be avoided completely.
Several systems exist for collecting spent ammunition for forensic investigation. These databases store images of cartridge cases and the marks on them. The research in this paper is focused on the different methods of feature selection and pattern recognition that can be used for comparison. For automatic comparison of these images it is necessary to extract firstly the useful parts of the images. On databases of 3800 images several processing steps have been tested and compared. The results and methods, which have been implemented, are presented. The usual correlation methods based on gray values of all relevant image data have been tested. They were useful in the database. Further invariant image descriptors and the a trous wavelet transform have been implemented. These methods are promising, however more investigation is needed for the use of these methods.
In a short period of two weeks experiments had to be done for court. The order was to investigate the effects of ballpoints shot transorbitally by a crossbow. The use of a high speed video camera turned out to be valuable for detailed observation of the ballpoint during launching and penetration of a gelatine model and demonstration of the results in court.
A database for toolmarks (named TRAX) and a database for footwear outsole designs (named REBEZO) have been developed on a PC. The databases are filled with video-images and administrative data about the toolmarks and the footwear designs. An algorithm for the automatic comparison of the digitized striation patterns has been developed for TRAX. The algorithm appears to work well for deep and complete striation marks and will be implemented in TRAX. For REBEZO some efforts have been made to the automatic classification of outsole patterns. The algorithm first segments the shoeprofile. Fourier-features are selected for the separate elements and are classified with a neural network. In future developments information on invariant moments of the shape and rotation angle will be included in the neural network.