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High-bandwidth 220 GHz experimental radar

ELECTRONICS LETTERS 2007年第20期43卷 1114-1116页

作者： Essen, H. Wahlen, A. Sommer, R. Johannes, W. Brauns, R. Schlechtweg, M. Tessmann, A. FGAN FHR MHS D-53343 Wachtberg Germany Fraunhofer Inst Appl Solid State Phys D-79108 Freiburg Germany

An experimental radar at 220 GHz has been developed, which is capable of delivering an instantaneous bandwidth of 8000 MHz. The solid-state radar uses an FM-CW waveform. The development is based on experience with a 94 GHz broadband measurement radar. The data undergo an ISAR imaging process to derive high-resolution scattering centre distributions for targets measured in tower/turntable configuration. High-resolution processing algorithms have been developed, which result in scattering centre distributions with a resolution better than 2 cm at ranges of and exceeding 200 m. The radar will be used for investigations on target signatures of small objects for stand-off detection of concealed weapons and other threat material.

关键词： broadband measurement radar Optical, image and video signal processing experimental radar solid-state radar radar resolution radar imaging high-resolution scattering frequency 220 GHz Radar equipment, systems and applications synthetic aperture radar CW radar FM-CW waveform FM radar ISAR imaging process

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Locally adaptive reconstruction of lost low frequency coefficients in wavelet coded images

Locally adaptive reconstruction of lost low frequency coeffi...

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Conference on Visual Communications and image processing 2007

作者： Rombaut, Joost Pizurica, Aleksandra Philips, Wilfried Univ Ghent Dept TELIN St Pietersniuwstraat 41 B-9000 Ghent Belgium

ISBN: (纸本)9780819466211

In packet switched networks such as the Internet, packets may get lost during transmission due to, e.g., network congestion. This leads to a quality degradation of the original signal. As video communication is a bandwidth consuming application, the original data are first compressed. This compression step increases the impact of information loss even more. In wavelet based image and video coding, the low frequency data is the most important. Loss of low frequency coefficients results in annoying black holes in the received images and video. This effect can be countered by post processing error concealment: a lost coefficient is estimated from its neighboring coefficients. In this paper we present a locally adaptive interpolation method for the lost low frequency coefficients. For each lost low frequency coefficient, we estimate the optimal interpolation direction (horizontal or vertical) using novel error measures. In this way, we preserve the edges in the reconstructed image much better. Compared to older techniques of similar complexity, our scheme reconstructs images with the same or better quality. This is reflected in the visual as well as in the numerical results: there is an increase of up to 4.4 dB compared to bilinear concealment. The proposed scheme is fast and simple, which makes it suitable for real-time applications.

关键词： image reconstruction error concealment packet loss wavelet coding

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applications of a neural network to estimate watermark embedding strength

Applications of a neural network to estimate watermark embed...

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8th International Workshop on image Analysis for Multimedia Interactive Services, WIAMIS 2007

作者： Jin, Cong Wang, Shihui Department of Computer Science Central China Normal University Wuhan 430079 China

ISBN: (纸本)076952818X

Digital watermarking technology has the advantages of easy implementation and capability of providing wide security services such as copyright protection, authentication and secret communication. In this paper, a digital watermarking scheme using neural network is proposed. Firstly, the original image is divided into some 88 blocks, and then neural networks according to different textural features and luminance of each block decide adaptively different embedding strengths. The watermark detection adopts correlation technology. Experimental results show that the proposed scheme has good imperceptibility and high robustness to common image processing operators. © 2007 IEEE.

关键词： Copyrights

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Diffuse matrix -: An optimized data structure for the storage and processing of hyperspectral images

Diffuse matrix -: An optimized data structure for the storag...

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2nd International Conference on signal processing and Multimedia applications

作者： Chaves-Gonzalez, Jose M. Vega-Rodriguez, Miguel A. Martinez-Cobo, Pablo J. Gomez-Pulido, Juan A. Sanchez-Perez, Juan M. Univ Extremadura Dept Technol Comp & Commun Escuela Politecn Campus Univ S-N Caceres 10071 Spain

ISBN: (纸本)9789898111135

This paper proposes a new format for storing and processing hyperspectral images captured by spectrometer AVIRIS (Airborne Visible/InfraRed Imaging Spectrometer). Obtaining such images is difficult, because the sensor that takes the images is carried in an aircraft that suffers turbulences while the camera is taking photos. So, a geo-rectification process is necessary to correct the information of different bands. The format proposed in this paper, DMF (Diffuse Matrix Format), allows a more efficient storage, because a list with the original information received in the sensor is saved for each position (x,Y) of the scanned ground. The format of the list saves space and time because no redundant information is saved using it. To show the possibilities of this new format an application that makes some thresholding and filter operations has been built. This program, firstly, creates the diffuse matrix in memory from the file that stores the image information, and then, some filter operations are executed over the diffuse matrix to check it. In this way, we prove that diffuse matrix processing is fast and simple, as well as the space used in the disk for its storage is quite less than the space used by typical formats.

关键词： hyperspectral data format diffuse matrix storage optimization geo-rectification AVIRIS images

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Reproduction of InSAR atmospheric signal using GPS data and atmospheric transport model

Reproduction of InSAR atmospheric signal using GPS data and ...

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Symposium on Remote Sensing and GIS Data processing and applications;and Innovative Multispectral Technology and applications

作者： Song, xiaogang Li, Deren Liao, Mingsheng Yang, Jie Wuhan Univ Sch Remote Sensing & Informat Engn Wuhan 430079 Peoples R China Wuhan Univ LIESMARS Wuhan 430079 Peoples R China

ISBN: (纸本)9780819469540

Atmospheric water vapor effects represents a major limitation to accuracy in InSAR applications. a method based on GPS-ZWD timeseries and atmospheric transport model is developed to reproduce InSAR atmospheric signal so as to be applied to reduce atmospheric effects in interferogram. Firstly, based on correlation between wator vapor effect and topography, topography-dependent component of delay variation can be estimated by fitting a model of the vertical profile of neutral atmospheric delay to the GPS ZWD measurements at the SAR overpass time, then we use the fitting model and a SRTM DEM of imaged area to generate a map of altitude-dependent ZWD delay difference, which can be used to reduce topography-dependent atmospheric phase in InSAR interferogram. After removing the topography-dependent model, the residual fluctuations can be interpreted as turbulent variations of water vapor. Atmospheric transport model is introduced to transform GPS-ZWD timeseries around SAR overpass time into a spatially denser network of GPS-ZWD control points. The denser network of GPS-ZWD enable estimation of ZWD difference maps that better match the turbulently-mixed atmospheric phase distortions observed in the InSAR data. Experimental data analysis showed the method to seperately consider topography-dependent and turbulent mixing atmospheric effects effectively reproduce atmospheric signal in InSAR interferogram.

关键词： InSAR GPS zenith wet delay(ZWD) atmospheric transport model(ATM)

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Steganography anomaly detection using simple one-class classification

Steganography anomaly detection using simple one-class class...

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Conference on Mobile Multimedia/image processing for Military and Security applications

作者： Rodriguez, Benjamin M. Peterson, Gilbert L. Agaian, Sos S. Univ Texas Dept Elect & Comp Engn San Antonio TX 78285 USA Univ Texas San Antonio Dept Elect & Comp Engn Multimedia & Mobile Signal Proc Lab San Antonio TX USA

ISBN: (纸本)9780819467010

There are several security issues tied to multimedia when implementing the various applications in the cellular phone and wireless industry. One primary concern is the potential ease of implementing a steganography system. Traditionally, the only mechanism to embed information into a media file has been with a desktop computer. However, as the cellular phone and wireless industry matures, it becomes much simpler for the same techniques to be performed using a cell phone. In this paper, two methods are compared that classify cell phone images as either an anomaly or clean, where a clean image is one in which no alterations have been made and an anomalous image is one in which information has been hidden within the image. An image in which information has been hidden is known as a stego image. The main concern in detecting steganographic content with machine learning using cell phone images is in training specific embedding procedures to determine if the method has been used to generate a stego image. This leads to a possible flaw in the system when the learned model of stego is faced with a new stego method which doesn't match the existing model. The proposed solution to this problem is to develop systems that detect steganography as anomalies, making the embedding method irrelevant in detection. Two applicable classification methods for solving the anomaly detection of steganographic content problem are single class support vector machines (SVM) and Parzen-window. Empirical comparison of the two approaches shows that Parzen-window outperforms the single class SVM most likely due to the fact that Parzen-window generalizes less.

关键词： classification steganography steganalysis anomaly detection

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Research on 10.6 μm laser beam monitoring in CO₂ laser processing system

Research on 10.6 μm laser beam monitoring in CO<sub>2</sub>...

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Conference on Infrared Materials, Devices and applications

作者： Shi, Yali Gao, Yunguo Deng, Weijie Shao, Shuai Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys Changchun 130033 Peoples R China

ISBN: (纸本)9780819470102

It is a key point of CO2 laser beam monitoring in the CO2 laser processing system to achieve alignment between CO2 laser and PL (pointing and launching, system, By monitoring the angle offset of CO2 laser beam, the compensation can be gotten witch is given to fast-steering mirror to rectify the direction of laser beam. But the normal photoelectric detector can not get the laser signal because of CO2 laser's high energy and long wavelength. Its wavelength is 10.6 mu m and its power can reach kW level. Consequently, it is difficult to detect the high-energy 10.6 mu m laser beam directly. So, we monitored the Output mirror of laser resonator superseded the laser beam, indirectly. The laser beam monitoring system could be designed based on CCD laser auto-collimation angular measurement principle and image processing method. In this paper, application of CCD laser auto-collimation angular measurement principle and image processing method for CO2 laser beam monitoring system is introduced particularly, After design, fabrication and alignment, the monitoring system can be used for experimental study that including angular measurement accuracy and angle offset measurement of CO2 laser beam. Angle offset range and angle variation rule of CO2 laser beam is also can be acquired for further research.

关键词： micro-angle sensor CCD laser auto-collimation CO2 beam monitoring image processing

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Multi-scale shape prior using wavelet packet representation and independent component analysis

Multi-scale shape prior using wavelet packet representation ...

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Medical Imaging 2007 Conference

作者： Zewail, Rami Elsafi, Ahmed Durdle, Nelson Univ Alberta Elect & Comp Engn Edmonton AB T6G 2V4 Canada

ISBN: (纸本)9780819466303

Statistical shape priors try to faithfully represent the full range of biological variations in anatomical structures. These priors are now widely used to restrict shapes;obtained in applications like segmentation and registration;to a subspace of plausible shapes. Principle component analysis (PCA) is commonly used to represent modes of shape variations in a training set. In an attempt to face some of the limitations in the PCA-based shape model, this paper describes a new multi-scale shape prior using independent component analysis (ICA) and adaptive wavelet decomposition. Within a best basis selection framework, the proposed method benefits from the multi-scale nature of wavelet packets, and the capability of ICA to capture higher order statistics in wavelet subspaces. The proposed approach is evaluated using contours from digital x-ray images of five vertebrae of human spine. We demonstrate the ability of the proposed shape prior to capture both local and global shape variations, even with limited number of training samples. Our results also show the performance gains of the ICA-based analysis for the wavelet sub-spaces, as compared to PCA-based analysis approach.

关键词： best basis selection statistical shape models PCA ICA wavelets

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signal processing core for high performance thermal imaging

Signal processing core for high performance thermal imaging

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Infrared Technology and applications xxxIII

作者： Lawrence, M. Ashley, S.F. Lupton, M. McEwen, R.K. Wilson, M. SELEX Sensors and Airborne Systems Ltd. United Kingdom

ISBN: (纸本)0819466646

In order to fully exploit emerging 3rd generation infrared detector technology, very high performance signal processing electronics are required in order to process in real-time, the vast amount of data that can be generated. This paper describes SELEx Sensors and Airborne System's most recent developments based upon the existing Sensor Integrated Modular Architecture (SiGMA) thermal imager. The key advances described in this paper include a modular architecture approach allowing physical separation of the processing core from the detector and proximity electronics, the miniaturisation of the processing electronics and the introduction of a solid state micro-scan mechanism which builds upon concepts developed during the company's previous work with uncooled infrared detector technology. The sensor architecture is initially designed to operate with the SELEx S&AS developed Hawk infrared detector, a medium waveband 640*512 element CMT array on a 16 micron pitch, but will also be compatible with the emerging Albion detector arrays, a medium waveband 1024*768 element CMT array on a 16 micron pitch and a long waveband 640*512 element CMT array on a 24 micron pitch. Other areas described are the development of advanced image processing algorithms including non-linear correction for display optimisation.

关键词： signal processing

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Simplified gabor wavelets for efficient feature extraction

Simplified gabor wavelets for efficient feature extraction

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IEEE Region 10 International Conference TENCON

作者： Wing-Pong Choi Siu-Hong Tse Kwok-Wai Wong Kin-Man Lam Centre for Signal Processing Department of Electronic and Information Engineering Hong Kong Polytechnic University Hong Kong China

Gabor wavelets (GWs) are commonly used for extracting local features for various applications like object detection, recognition and tracking. However, extracting Gabor features is computationally intensive, so the features are impractical for real-time applications. In this paper, we propose a simplified version of Gabor wavelets (SGWs) and an efficient algorithm for extracting the features based on an integral image. We evaluate the performance of the SGWs for face recognition. Experimental results show that SGWs can achieve a performance level similar to GWs, while the runtime for feature extraction using SGWs is about 4.39 times faster than that of GWs, implemented by using fast Fourier transform (FFT).

关键词： Feature extraction Quantization Face recognition Computational complexity Data mining Object detection Fast Fourier transforms signal processing signal processing algorithms Runtime

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