Image enhancement of pre-processed and colored fingerprints such as ninhydrin-processed fingerprints in a complexpatterned background is important in crime investigation. Contrast adjustment, which is one of the most common image processing methods usually has a limitation in enhancing such fingerprints because of interference superposing patterns of the background. We propose three image processing methods using color information or spatial frequency information of an RGB material image. The first method is a hue-based method, which converts hue values of each pixel in CIELAB color space to corresponding brightness. The second method is a PCA-based method, which conducts principal component analysis on a color data of the material image and reconstructs three principal component images. Both proposed methods achieve more enhanced fingerprint images than the contrast adjustment gives. The PCA-based method works well even when the hue-based method does not. As the third proposed method, remaining background periodic patterns are removed for fingerprint enhancement by spatial frequency filtering using the Fast Fourier Transformation. According to estimated frequency components of background periodic patterns, we altered the width of frequency removing region of such background patterns, suggesting that there is an optimal width for each material for fingerprint enhancement. Also, we tested four different edge profiles of the frequency removing region and checked that an edge profile with gradual change tends to reduce the effect of suppressing the background periodic patterns compared to an edge profile with sharp change under the equivalent width of removing region of frequency components.
We applied a wide-field time-resolved luminescence (TRL) method with a pulsed laser and a gated intensified charge coupled device (ICCD) for deciphering obliterated documents for use in forensic science. The TRL method can nondestructively measure the dynamics of luminescence, including fluorescence and phosphorescence lifetimes, which prove to be useful parameters for image detection. First, we measured the TRL spectra of four brands of black porous-tip pen inks on paper to estimate their luminescence lifetimes. Next, we acquired the TRL images of 12 obliterated documents at various delay times and gate times of the ICCD. The obliterated contents were revealed in the TRL images because of the difference in the luminescence lifetimes of the inks. This method requires no pretreatment, is nondestructive, and has the advantage of wide-field imaging, which makes it is easy to control the gate timing. This demonstration proves that TRL imaging and spectroscopy are powerful tools for forensic document examination.
Actual case examples and further improvements on source camera identification are shown. There are three specific topics in this paper: (a) In order to improve performance of source camera identification, the hybrid identification scheme using both dark current non-uniformity (DCNU) and photo-response non-uniformity (PRNU) is proposed. The experimental results indicated that identification performance would be improved by properly taking advantage of their features; (b) Source camera identification using non-uniform nature of the CCD charge transfer circuit is proposed. The experimental results with twenty CCD modules of the same model showed that individual camera identification for dark images was possible by the proposed method. Furthermore, it was shown that the proposed method had higher discrimination capability than the method using pixel non-uniformity when the number of recorded image was small; (c) The authors have been performed source camera identification in the five actual criminal cases, such as homicide case, and so on. The analytical procedure was a sequential examination of hot pixel coordinates validation followed by the similarity evaluation of sensor noise pattern. The authors could clearly prove that the questioned criminal scenes had been recorded by the questioned cameras in four cases of the five.
Radiation-induced malfunction and degradation of electronic modules in certain operating
conditions are described in this report. The cumulative radiation effects on Atmel AVR
microcontrollers, and 2.4 GHz and 303 MHz wireless network devices were evaluated under
gamma ray irradiation with dose rates of 100, 10 and 3 Gy/h. The radiation-induced
malfunctions occurred at doses of 510±22 Gy for AVR microcontrollers, and 484±111 and
429±14 Gy for 2.4 GHz and 303 MHz wireless network devices, respectively, under a 100 Gy/h
equivalent dose rate. The degradation of microcontrollers occurred for total ionizing doses
between 400 and 600 Gy under X-ray irradiation. In addition, we evaluated the reliability of
neutron dosimeters using a standard neutron field. One of the neutron dosimeters gave a reading
that was half of the standard field value.
In this study, we discussed individual camera identification of CMOS cameras, because CMOS (complementary-metal-oxide-semiconductor) imaging detectors have begun to make their move into the CCD (charge-coupled-device) fields for recent years. It can be identified whether or not the given images have been taken with the given CMOS camera by detecting the imager's intrinsic unique fixed pattern noise (FPN) just like the individual CCD camera identification method proposed by the authors. Both dark and bright pictures taken with the CMOS cameras can be identified by the method, because not only dark current in the photo detectors but also MOS-FET amplifiers incorporated in each pixel may produce pixel-to-pixel nonuniformity in sensitivity. Each pixel in CMOS detectors has the amplifier, which degrades image quality of bright images due to the nonuniformity of the amplifier gain. Two CMOS cameras were evaluated in our experiments. They were WebCamGoPlus (Creative), and EOS D30 (Canon). WebCamGoPlus is a low-priced web camera, whereas EOS D30 is for professional use. Image of a white plate were recorded with the cameras under the plate's luminance condition of 0cd/m2 and 150cd/m2. The recorded images were multiply integrated to reduce the random noise component. From the images of both cameras, characteristic dots patterns were observed. Some bright dots were observed in the dark images, whereas some dark dots were in the bright images. The results show that the camera identification method is also effective for CMOS cameras.
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.
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.
The purpose of this study is visualization of concealed light elements materials in metallic environments using a cooled CCD camera with an image intensifier. In this study, gamma-rays were used for visualization. As a gamma-ray source, radio-isotopes such as 57Co, 133Ba and 137Cs were used. Gamma-rays penetrate through sample materials and are firstly enhanced by an image intensifier and then detected by a cooled CCD camera. Materials such as explosives or organic matters were observed through various metal plates.
We have studied a multi-frame image processing method for recognition of degraded car license plate images. In actual situations, various distortions such as geometric distortions or various blurs are imposed on recorded images. Therefore in order to apply the multi-frame image processing method to moving objects, it is necessary to correct geometric distortions. When images are blurred with out-of- focusing or motion blur, it is necessary to remove or suppress such distortions. In this report, we examined the geometric distortion correction and deblurring for multi- frame image processing and confirmed the effectiveness of the method. The example for real videotaped images is also shown in this report. As a result, it is recognized that the multi-frame image processing method is effective for recognizing characters on moving car license plates.
We studied the influence of an aperture shape of a diaphragm on the restoration of low quality out-of-focus video images. We measured PSF of three consumer video cameras which are equipped with different types of the diaphragm system. In this measurements, the appropriateness of the assumption of space-invariant PSF and the aperture-size-dependence of the geometrical shape of PSF were examined. Although rotationally symmetric PSF has been assumed in many studies, it was recognized that the shape of PSF is not circular but triangular or rhomboid in many cases. Moreover, the shape depends both on the camera type and the aperture opening ratio. We applied the measured PSF to the restoration of the blurred images taken by the home video cameras. The Wiener filtering technique was used to restore the images. More desirable images were obtained by approximating PSF to two triangular disks on the basis of the measurement than by approximating PSF to a circular disk or a gaussian function.
We have studied the use of point spread function (PSF) calculated by the wave optics for restoration of out-of- focused images. According to the theory, PSF and its Fourier transform OTF depend only on the defocus quantity (Delta) which can be calculated by using physical quantities of a lens. It is recognized that large objects in out-of-focused images can be restored well by using calculated PSF or OTF when a diaphragm is circular and (Delta) is estimated adequately. However details can not be restored well especially when (Delta) is large. Difference is recognized between PSF based on the geometrical optics and PSF based on the wave optics. It is recognized that images obtained by using PSF calculated by the wave optics are better in sharpness than by using PSF calculated by the geometrical optics. Such difference becomes larger as (Delta) becomes smaller. In the case that the diaphragm differs from a circular disc such as home video cameras, it is important to take the diaphragm form into account.
An x-ray image intensified cooled CCD camera (x-ray IICCCDC) with micro-focused x-ray source, is a very powerful tool for objects investigation. We can get inside images of objects non destructively and we can also get magnified images of the objects. We investigate illegal electronic circuits, forged IC chips, etc. by the x-ray IICCCDC. The data depth of each pixel of the image taken by the x-ray IICCCDC is 14 bits. The x-ray IICCCDC is a powerful tool for itself, but the raw images of that are degraded by many factors, a geometrical distortion, lack of uniformity of an x-ray window's material, blurring caused by finite size of the x- ray source, background noise by x-ray scattering, etc. Some of these degradation factors are well defined and the degradation can be restored well, but some of these degradation can not be recovered well. We analyzed the sources of degradation and applied digital image processing techniques to the images of the x-ray IICCCDC to enhance the image quality. Using these digital image processing techniques, the image quality of the x-ray IICCCDC was enhanced substantially.
KEYWORDS: Video, Video surveillance, Image processing, Video processing, Image enhancement, Laser processing, Signal to noise ratio, Control systems, Computing systems, Frame grabbers
We developed a new video image processing system that consists of a laser videodisc recorder (LVR) which is controlled by a personal computer through an RS232C interface. Using this system, we can handle video images without degradation of images due to the damage of videotapes and it becomes easy to conduct multiframe image processing. We wrote a computer controlled image processing procedure for video images. We performed experiments using video images recorded by a normal 8 mm video at night. As a result, it is recognized that our new system and procedures are effective for improving the signal to noise ratio and reducing the line to line jitters. Processed results for car license plate images that are recorded on videotapes are shown. We also show examples of actual cases in which characters on the license plate can be readable after processing.
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