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conference on High-Resolution Wavefront Control - Methods, Devices, and applications

作者： McCarthy, DF USA Res Lab Informat Sci & Technol Directorate Adelphi MD 20783 USA

ISBN: (纸本)0819432466

We have developed a digital image processing system for real-time digital image processing feedback control of adaptive optics systems and simulation of optical image processing algorithms. The system uses multi-computer architecture to capture data from an imaging device such as a charge coupled device (CCD) camera, process the image data, and control a spatial light-modulator, typically a liquid crystal (LC) modulator or a micro-electro mechanical system (MEMS). The system is a Windows NT Pentium-based system combined with a commercial off-the-shelf (COTS) peripheral component interconnect (PCI) bus multi-processor system. The multi-processor is based on the Analog Devices super Harvard architecture computer (SHARC) processor, and field programmable gate arrays (FPGAs). The SHARCs provide a scalable reconfigurable C language-based digital signal processing (DSP) development environment. The FPGAs are typically used as reprogrammable interface controllers designed to integrate several off-the-shelf and custom imagers and light modulators into the system. The FPGAs can also be used in concert with the SHARCs for implementation of application-specific high-speed DSP algorithms.

关键词： digital signal processing adaptive optics real-time image processing SHARC FPGA

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Efficient image database retrieval using wavelet packets and Principal Component Analysis

Efficient image database retrieval using wavelet packets and...

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conference on Wavelet applications in signal and image processing VII

作者： Saeed, M Rabiee, H MIT Dept Elect Engn & Comp Sci Cambridge MA 02139 USA

ISBN: (纸本)0819432997

With the advancement of multimedia technology and the internet, numerous applications have arisen which require the storage and retrieval of large image and video databases. A novel method (Eigenwavelet) was developed to retrieve images from a large heterogeneous image database upon a user-specified query. The queries are in the form of an image(s) that the user seeks to find similar matches to in the database. Using the queries, an efficient algorithm was developed which decomposed each image in the database using wavelet packet analysis. Along each node of the packet tree, Principal Component Analysis (PCA) was applied to the: database images after wavelet packet decomposition, and a set of eigenvectors were generated for each node of the packet tree. To search the image database, the query images are projected onto these eigenvectors (Eigenwavelet coefficients). A distance metric is computed between the projections of the queries and the projections of the images in the database onto the eigenwavelets. Those images with minimal distance (L1) are retrieved in response to a unique query set. Simulations with a heterogeneous image database suggest the Eigenwavelet method of image retrieval is a robust and computationally tractable method of retrieving images with a probability of detection > .8.

关键词： image retrieval wavelet packets Principal Component Analysis image metrics

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Implementation of real-time SAR-systems with a high performance digital signal processor

Implementation of real-time SAR-systems with a high performa...

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conference on image and signal processing for Remote Sensing V

作者： Kloos, H Wittenburg, JP Hinrichs, W Lieske, H Pirsch, P Univ Hannover Informat Technol Lab D-30167 Hannover Germany

ISBN: (纸本)0819434663

Real-time Synthetic Aperture Radar (SAR) image synthesis is one of the major problems to solve in the future. To achieve a fully synthesized SAR image, the raw signal must be filtered with a 2-dimensional function representing the system transfer function. These filtering operations are usually processed by multiplication in frequency domain. Therefore, the Fast Fourier Transform (FFT) used for transformation to I from frequency domain is the predominant algorithm in terms of processing power for SAR image synthesis. The presented HiPAR-DSP is a programmable architecture, which is optimized for FFT-dominated applications like SAR image processing. To provide the high requested processing power for these task, the HiPAR-DSP has an array of 4 (HiPAR-DSP4) respectively 16 (HiPAR-DSP16) parallel processing units (datapaths) which is controlled by an single RISC Controller. For data exchange between the processing units there is a shared memory which allows the concurrent access from all processing units in a single clock cycle. So the HiPAR-DSP16 performs a complex FFT with 1024 Samples in 32 mu s. For the implemented SAR-processing task, the Range Compression with 4096 complex samples per line we achieve a real-time performance of nearly 1500 rangelines/s.

关键词： SAR processing digital signal processor (DSP) FFT processing

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Painless approximation of dual frames, with applications to shift-invariant systems

Painless approximation of dual frames, with applications to ...

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conference on Wavelet applications in signal and image processing VII

作者： Strohmer, T Univ Calif Davis Dept Math Davis CA 95616 USA

ISBN: (纸本)0819432997

We analyse the relation between infinite-dimensional frame theory and finite-dimensional models for frames as they are used for numerical algorithms. Special emphasis in this paper is on perfect reconstruction oversampled filter banks, also known as shift-invariant frames. For certain finite-dimensional models it is shown that the corresponding finite dual frame provides indeed an approximation of the dual frame of the original infinite-dimensional dual frame. For filter banks on l(2)(Z) we derive error estimates for the approximation of the synthesis filter bank when the analysis filter bank satisfies certain decay conditions. We show how one has to design the finite-dimensional model to preserve important structural properties of filter banks, such as polyphase representation. Finally an efficient regularization method is presented to solve the ill-posed problem arising when approximating the dual frame on L-2(R) via truncated Gram matrix.

关键词： frames finite sections filter banks Toeplitz matrix dual frame

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Minimax solution of inverse problems and deconvolution by mirror wavelet thresholding

Minimax solution of inverse problems and deconvolution by mi...

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conference on Wavelet applications in signal and image processing VII

作者： Kalifa, J Mallat, S Rougé, B Ecole Polytech CMAP F-91128 Palaiseau France

ISBN: (纸本)0819432997

We consider ill-posed inverse problems where inverting the distortion of signals and images in presence of additive noise is numerically unstable. The properties of linear and non-linear diagonal estimators in an orthogonal basis lead to general conditions to build nearly minimax optimal thresholding estimators. The deconvolution of bounded variation signals and images is studied in further details, with an application to the deblurring of satellite images. Besides their optimality properties, a competition set by the French spatial agency (CNES) showed that this type of algorithms gives the best numerical results among all competing algorithms.

关键词： inverse problems denoising minimax estimation diagonal linear and non-linear estimators thresholding estimators bounded variation signals wavelet packets deconvolution satellite image deblurring

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Design of the integrated sensor system for two-dimension position based on CCD

Design of the integrated sensor system for two-dimension pos...

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SPIE conference on Advanced Photonic Sensors and applications

作者： Liu, xD Gu, YZ Zhejiang Univ Dept Opt Engn Hangzhou 310027 Peoples R China

ISBN: (纸本)081943499X

In this Article, a kind of design philosophy of a integrated sensor system for two-dimension position is presented. The sensing unit of this system is a two-dimension CCD (Charge-Coupled Device). Through increasing the signal-to-noise ratio of a constructed specific lightspot target and performing optical filter, the exported full video image signal of CCD which includes a group of isolated positive pulse caused by the target is formed. Through combinational logic and sequential logic processing to the full video signal, the target image's two-dimension position on the light sensitive layer of CCD can be generated. Finally, the specific fightspot target's relative two-dimension position in the visual field is gained. In addition, a typical application of the system in the computer information processing field are presented as well.

关键词： two-dimension position CCD full video signal specific lightspot target

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Multi-scale blind deconvolution of sensor array signals via scale transform

Multi-scale blind deconvolution of sensor array signals via ...

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conference on Advanced signal processing Algorithms, Architectures, and Implementations Ix

作者： Izzetoglu, M Akgül, T Drexel Univ Dept Elect & Comp Engn Philadelphia PA 19104 USA

ISBN: (纸本)0819432938

In this paper we introduce a. multi-scale deconvolution technique performed in the scale-domain. In sensor array applications such as in radar, sonar and seismic processing, the sensor outputs are modeled as the convolution of the unknown source signal with various unknown system impulse responses that are scaled versions of each other with unknown scale parameters. In many applications these signals or the scaling parameters are needed to be estimated only from the sensor outputs. In our earlier work, we estimated the unknown scale parameters by using properties of the scale transform and then employed existing deconvolution algorithms. Here, we derive the multiscale blind deconvolution algorithm in the scale transform domain. The performance of the method is illustrated using simulation examples.

关键词： Sensors Deconvolution Reflectors Convolution signal processing Algorithm development Computer simulations Electronic filtering image processing Radar

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Multiresolution estimation of fractal dimension from images affected by signal-dependent noise

Multiresolution estimation of fractal dimension from images ...

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conference on Wavelet applications in signal and image processing VII

作者： Aiazzi, B Alparone, L Baronti, S Garzelli, A CNR IROE Nello Carrara Res Inst Electromagnet Waves I-50127 Florence Italy

ISBN: (纸本)0819432997

A well-suited approach to calculate the fractal dimension of digital images stems from the power spectrum of a fractional Brownian motion: the ratio between powers at different scales is related to the persistence parameter H and, thus, to the fractal dimension D = 3 - H. The signal-dependent nature of the speckle noise, however, prevents from a correct estimation of fractal dimension from Synthetic Aperture Radar (SAR) images. Here, we propose and assess a novel method to obtain D based on the multiscale decomposition provided by the normalized Laplacian pyramid (NLP), which is a bandpass representation obtained by dividing the layers of an LP by its expanded baseband and is designed to force the noise to become signal-independent. Extensive experiments on synthetic fractal textures, both noise-free and noisy, corroborate the underlying assumptions and show the performances, in terms of both accuracy and confidence of estimation, of pyramid methods compared with the well-established method based on the wavelet transform. Preliminary results on true SAR images from ERS-1 look promising as well.

关键词： fractional Brownian motion fractal dimension power spectrum multiresolution analysis wavelet transform Laplacian pyramid Synthetic Aperture Radar (SAR) images speckle texture

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Special class of orthonormal wavelets: Theory, implementations, and applications

ICASSP, IEEE International Conference on Acoustics, Speech a...

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ICASSP, IEEE International conference on Acoustics, Speech and signal processing - Proceedings 1999年 3卷 1225-1228页

作者： Shen, Lixin Tham, Jo Yew Lee, Seng Luan Tan, Hwee Huat Natl Univ of Singapore Singapore Singapore

This paper introduces a novel class of length-4N orthonormal scalar wavelets, and presents the theory, implementational issues, and their applications to image compression. We first give the necessary and sufficient conditions for the existence of this class. The parameterized representation of filters with different lengths are then given. Next, we derive new and efficient decomposition and reconstruction algorithms specifically tailored to this class of wavelets. We will show that the proposed discrete wavelet transformations are orthogonal and have lower computational complexity than conventional octave-bandwidth transforms using Daubechies' orthogonal filters of equal length. In addition, we also verify that symmetric boundary extensions can be applied. Finally, our image compression results further confirm that improved performance can be achieved with lower computational cost.

关键词： Wavelet transforms

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Acquirement of digital solar magnetic images

Acquirement of digital solar magnetic images

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conference on applications of Digital image processing xxII

作者： Zhang, B Deng, YY Wang, JS Beijing Astron Observ Beijing 100012 Peoples R China

ISBN: (纸本)0819432946

The solar vector magnetograph system in Huai Rou Solar Observation station (HRSO) is described in this paper. First the measuring principle of magnetic field and velocity field are discussed. We take the simple two-passband birefringent filter as an example to explain the working principle of the narrow-band birefringent filter which is the core of acquiring magnetic field and velocity field. Then the 35 cm Solar Magnetic Field Telescope is described, including optic system, camera system and digital system. In camera system the advantages of scientific Charge Coupled Devices (CCD) are described. In digital system we introduce the necessary functions of image grabber which is suitable for acquiring solar magnetic field. At last the performance of the whole system is discussed such as resolution and signal-to-noise ratio, and one magnetic field image and one velocity field image in the same area on the Sun are shown.

关键词： magnetic field birefringent filter CCD frame transfer real-time image grabber

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