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Medical Imaging 2004 Conference

作者： Lauritsch, G Katsevich, A Hirsch, M Siemens Med Solut D-91301 Forchheim Germany

ISBN: (纸本)0819452831

In multi-slice spiral computed tomography (CT) there is an obvious trend in adding more and more detector rows. The goals are numerous: volume coverage, isotropic spatial resolution, and speed. Consequently, there will be a variety of scan protocols optimizing clinical applications. Flexibility in table feed requires consideration of data redundancies to ensure efficient detector usage. Until recently this was achieved by approximate reconstruction algorithms only. However, due to the increasing cone angles there is a need of exact treatment of the cone beam geometry. A new, exact and efficient 3-PI algorithm for considering three-fold data redundancies was derived from a general, theoretical framework based on 3D Radon inversion using, Grangeat's formula. The 3-PI algorithm possesses a simple and efficient structure. This publication deals with a thorough evaluation of the performance of the 3-PI algorithm in comparison to the I-PI method for non-redundant data. image quality of the 3-PI algorithm is superior. The prominent spiral artifacts and other discretization artifacts are significantly reduced due to averaging effects when taking into account redundant data. Certainly signal-to-noise ratio is increased. The computational expense is comparable even to that of approximate algorithms. The 3-PI algorithm proves its practicability for applications in medical imaging.

关键词： image reconstruction computed tomography spiral CT cone-beam theoretically exact filtered backprojection algorithm reduced pitch data redundancy

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wavelets: a tool for efficient data representation

Wavelets: a tool for efficient data representation

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International Conference on Computer Graphics, Imaging and Visualization, CGIV

作者： S.L. Lee National University of Singapore Singapore

More often than not information is embedded in massive amount data corrupted with noise. Efficient representation of data will facilitate processing of information contained in the data. wavelets are a new mathematical tool for data representation, and are particularly efficient in reducing the number of parameters in the representation, a process known as data compression. This talk is a visual presentation of the applications of wavelets, including image, video and other data compression as well as denoising and signal separation. Some mathematical aspects of wavelets will also be presented.

关键词： Data compression Application software Videoconference Video compression Noise reduction Source separation Computer graphics Data visualization

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POCS supperresolution image reconstruction using wavelet transform

POCS supperresolution image reconstruction using wavelet tra...

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Proceedings of 2004 International Symposium on Intelligent signal processing and Communication Systems, ISPACS 2004

作者： Tian, Bin Sclabassi, Robert J. Hsu, Jennting T. Liu, Qiang Pon, Lin-Sen Li, Ching-Chung Sun, Mingui State Key Laboratory of Integrated Services Networks Xidian University Xi'an Shaanxi 710071 China Laboratory for Computational Neuroscience University of Pittsburgh Pittsburgh PA 15260 United States Departments of Neurological Surgery University of Pittsburgh Pittsburgh PA 15260 United States Department of Biomedical Engineering University of Pittsburgh Pittsburgh PA 15260 United States Department of Electrical Engineering University of Pittsburgh Pittsburgh PA 15260 United States

ISBN: (纸本)0780386396

Research interest in multi-frame supperresolution has risen substantially in recent years and it is expected to have wide applications to medicine. This paper presents a modified Projection Onto Convex Set (POCS) superresolution method based on wavelet transform. Based on the principle of POCS, an iterative procedure is proposed to extract information hidden in a group of low resolution images to update the corresponding high frequency band of the reference image, thus augment the individual low-resolution image to a high resolution image. The simulation results show that the new proposed algorithm is effective in constructing high-resolution medical images. ©2004 IEEE.

关键词： image reconstruction

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Hand held hyperspectral imager for standoff detection of chemical and biological aerosols

Hand held hyperspectral imager for standoff detection of che...

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Conference on Chemical and Biological Sensing V

作者： Hinnrichs, M James, JB Mc Anally, G Pacific Adv Technol Santa Ynez CA 93460 USA

ISBN: (纸本)0819453390

Pacific Advanced Technology has developed a small hand held imaging spectrometer, Sherlock for gas leak and aerosol detection and imaging. The system is based on a patented technique, (IMSS image Multi-spectral Sensing), that uses diffractive optics and image processing algorithms to detect spectral information about objects in the scene of the camera. This cameras technology has been tested at Dugway Proving Ground and Dstl Porton Down facilities looking at Chemical and Biological agent simulants. In addition to Chemical and Biological detection, the camera has been used for environmental monitoring of green house gases and is currently undergoing extensive laboratory and field testing by the Gas Technology Institute, British Petroleum and Shell Oil for applications for gas leak detection and repair.

关键词： Mid-IR Cameras Absorption Imaging systems Aerosols Biological detection systems Long wavelength infrared Standoff detection Clouds signal to noise ratio

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Multi-sensor cargo bay fire detection system

Multi-sensor cargo bay fire detection system

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Conference on Enabling Photonic Technologies for Aerospace applications VI

作者： Snyder, BL Anderson, KJ Renken, CH Socha, DM Miller, MS Goodrich Corp Adv Sensors Tech Ctr Burnsville MN 55306 USA

ISBN: (纸本)0819453587

Current aircraft cargo bay fire detection systems are generally based on smoke detection. Smoke detectors in modern aircraft are predominately photoelectric particle detectors that reliably detect smoke, but also detect dust, fog, and most other small particles. False alarms caused by these contaminants can be very costly to the airlines because they can cause flights to be diverted needlessly. To minimize these expenses, a new approach to cargo bay fire detection is needed. This paper describes a novel fire detection system developed by the Goodrich Advanced Sensors Technical Center. The system uses multiple sensors of different technologies to provide a way of discriminating between real fire events and false triggers. The system uses infrared imaging along with multiple, distributed chemical sensors and smoke detectors, all feeding data to a digital signal processor. The processor merges data from the chemical sensors, smoke detectors, and processed images to determine if a fire (or potential fire) is present. Decision algorithms look at all this data in real-time and make the final decision about whether a fire is present. In the paper, we present a short background of the problem we are solving, the reasons for choosing the technologies used, the design of the system, the signal processing methods and results from extensive system testing. We will also show that multiple sensing technologies are crucial to reducing false alarms in such systems.

关键词： infrared imaging image processing chemical sensing fire detection smoke detectors

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Watermarking via optimization algorithms for quantizing randomized image characteristics

Watermarking via optimization algorithms for quantizing rand...

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IEEE signal processing and Communications applications (SIU)

作者： M.K. Mihcak Cryptography and Anti-Piracy Group Microsoft Research Redmond WA USA

We introduce a novel approach for blind and semi-blind watermarking and apply it to images. We derive randomized robust semi-global features of images in a suitable transform domain (wavelets in case of images) and quantize them in order to embed the watermark. Quantization is carried out by embedding to the host a sequence computed by solving an optimization problem whose parameters are known to the information hider, but unknown to the attacker. We experimentally identify some conditions (our randomization is aimed at achieving them) satisfied by our parameters, which formally and experimentally imply the robustness of our algorithm against malicious optimal estimation attacks. Furthermore, we experimentally show the robustness of our algorithm against many generic benchmark attacks for a large number of images.

关键词： Watermarking Robustness Cryptography Wavelet transforms Wavelet domain Quantization Embedded computing Hip Structural beams

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Stochastic modeling of the spatiotemporal wavelet coefficients and applications to quality enhancement and error concealment

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EURASIP JOURNAL ON APPLIED signal processing 2004年第12期2004卷 1931-1942页

作者： Feideropoulou, G Pesquet-Popescu, B Ecole Natl Super Telecommun Bretagne Signal & Image Proc Dept F-75634 Paris 13 France

We extend a stochastic model of hierarchical dependencies between wavelet coefficients of still images to the spatiotemporal decomposition of video sequences, obtained by a motion-compensated 2D+t wavelet decomposition. We propose new estimators for the parameters of this model which provide better statistical performances. Based on this model, we deduce an optimal predictor of missing samples in the spatiotemporal wavelet domain and use it in two applications: quality enhancement and error concealment of scalable video transmitted over packet networks. Simulation results show significant quality improvement achieved by this technique with different packetization strategies for a scalable video bit stream.

关键词： wavelets spatiotemporal decompositions stochastic modeling hierarchical dependencies video quality scalability

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Comparison of the binary phase only filter design by DBS algorithm with the classical SDF filter

Comparison of the binary phase only filter design by DBS alg...

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Conference on Military Remote Sensing

作者： Butt, JA Wilkinson, TD Univ Cambridge Dept Engn Photon & Sensors Grp Cambridge CB2 1PZ England

ISBN: (纸本)0819455660

The joint transform correlator (JTC) is one of two main optical image processing architectures which provide us with a highly effective way of comparing images in a wide range of applications. Traditionally an optical correlator is used to compare an unknown input scene with a pre-captured reference image library, to detect if the reference occurs within the input. There is a new class of application for the JTC where they are used as image comparators, not having a known reference image, rather frames from a video sequence form both the input and reference. The JTC input plane is formed by combining the current frame with the previous frame in a video sequence and if the frames match, then there will be a correlation peak. If the objects move then the peaks will move (tracking) and if something has changed dramatically in the scene, then the correlation between the two frames is lost. This forms the basis of a very powerful application for the JTC in Defense and Security. Any change in the scene can be recorded and with the inherent shift invariance property of the correlator, any movement of the objects in the scene can also be detected. A major limitation of the JTC is its intolerance to rotation and scale changes in images. The strength of the Correlation signal decreases as the input object rotates or varies in scale relative to the reference object. We have designed a binary phase only filter using the direct binary search algorithm for rotation invariant pattern recognition to be implemented on a JTC and compared to a classical synthetic discriminant function (SDF) filter. Results show that the performance of the DBS filter is better than the SDF filter.

关键词： image filtering Optical correlators Binary data Spatial light modulators Optical filters Phase only filters Virtual colonoscopy Fourier transforms image processing Video

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A multiresolution directional filter bank for image applications

A multiresolution directional filter bank for image applicat...

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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： T.T. Nguyen S. Oraintara Department of Electrical Engineering University of Texas Arlington Arlington TX USA

We propose a new formulation of directional filter banks (DFBs). By using a non-uniform and non-separable filter bank, a critically sampled multiresolution directional image representation can be obtained efficiently. The resulting DFB yields non-uniform frequency division which is composed of one lowpass channel with a decimation factor of one-fourth and six highpass directional channels with a decimation factor of one-eighth. It overcomes the limited directional selectivity of separable wavelets and the limited resolution of the conventional DFB. The lowpass channel can be used to obtain multiresolution representation by simply re-iterating the same DFB decomposition. On the other hand, the directional subbands can be further refined by simply applying a two-channel DFB at each highpass channel. A simple design method yielding near orthogonal uniform and non-uniform multidimensional filter banks is discussed, and, finally, a numerical experiment is presented to demonstrate the potential of the new image basis.

关键词： image resolution Filter bank Discrete wavelet transforms signal resolution image reconstruction Discrete transforms Binary trees image representation Frequency conversion Design methodology

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Digital x-ray imaging and image processing for object detection in closed containers

Digital x-ray imaging and image processing for object detect...

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Proceedings of the Seventh IASTED International Conference on Computer Graphics and Imaging

作者： Kröger, Chris Bartle, C.M. West, J.G. Tran, Vi-Hoa ISOSCAN Inst. of Geol. and Nuclear Sciences PO Box 31312 Lower Hutt New Zealand University of California at Davis Dept. of Biomedical Engineering United States

We are presenting a technique to analyze digital x-ray images of industrial products to detect undesired foreign objects. Products are made of fairly homogenous material such as meat in a cardboard container. The main advantage of the method is its high speed and low false detection rate. image retrieval is performed through x-ray scanning of the entire container, where the attenuated signal is recorded at the detector arrays. Spectral analysis of the resulting intensity image will filter intensities not belonging to the main content of the container, assuming that the main packing follows a distinct intensity distribution. This distinct intensity distribution is determined for each image as a base for further analysis. Filtered suspected intensities can be used for the rendering of the object or to notify detection for further action. Several advantages follow from this technique: Firstly, it is independent of the shape of the object as no edge detection is needed. Secondly, the calculations can be performed very fast, as only part of the intensity spectrum is used for the analysis, and thirdly, very little false detections are encountered. For these reasons the technique is ideal for inline purposes such as conveyor belt driven applications.

关键词： Medical imaging

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