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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Segall, CA Katsaggelos, AK Northwestern Univ Dept Elect & Comp Engn Evanston IL 60208 USA

ISBN: (纸本)0780370414

A novel fidelity constraint to the image enhancement problem is presented. With this constraint, we exploit the motion vectors of a compressed video bit-stream. These vectors establish a correspondence between image pixels across a series: of frames, and we guarantee that processing the decoded sequence does not violate this correspondence. We develop the constraint within the context of MPEG-2 and incorporate the constraint into a regularized enhancement algorithm. Simulations are then performed. Quantitative and qualitative results illustrate an improvement in visual quality.

关键词： image enhancement

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An unsupervised segmentation algorithm based on an iterative spectral dissimilarity measure for hyperspectral imagery

An unsupervised segmentation algorithm based on an iterative...

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Conference on visual communications and image processing 2001

作者： Kwon, H Der, SZ Nasrabadi, NM USA Res Lab Adelphi MD 20783 USA

ISBN: (纸本)0819439886

We present an adaptive unsupervised segmentation technique, in which spectral features are obtained and processed without a priori knowledge of the spectral characteristics. The proposed technique is based on an iterative method, in which segmentation at a given iteration depends closely on the segmentation results at the previous iteration. The hyperspectral images are first coarsely segmented and then the segmentation is successively refined via an iterative spectral dissimilarity measure. The algorithm also provides reduced computational complexity and improved segmentation performance. The algorithm consists of (i) an initial segmentation based on a fixed spectral dissimilarity measure and the k-means algorithm, and (ii) subsequent adaptive segmentation based on an iterative spectral dissimilarity measure over a local region whose size is reduced progressively. The iterative use of a local spectral dissimilarity measure provided a set of values that can discriminate among different materials. The proposed unsupervised segmentation technique proved to be superior to other unsupervised algorithms, especially when a large number of different materials are mixed in complex hyperspectral scenes.

关键词： multispectral processing unsupervised segmentation hyperspectral imagery adaptive segmentation

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Space-scale adaptive noise reduction in images based on thresholding neural network

Space-scale adaptive noise reduction in images based on thre...

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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Zhang, XP Ryerson Polytech Inst Dept Elect & Comp Engn Toronto ON M5B 2K3 Canada

ISBN: (纸本)0780370414

Noise reduction has been a traditional problem in image processing. Recent wavelet thresholding based denoising methods proved promising, since they are capable of suppressing noise while maintaining the high frequency signal details. However, the local space-scale information of the image is not adaptively considered by standard wavelet thresholding methods. In this paper, a new type of thresholding neural networks (TNN) is presented with a new class of smooth nonlinear thresholding functions being the activation function. Unlike the standard soft-thresholding function, these new nonlinear thresholding functions are infinitely differentiable. Then a new nonlinear 2-D space-scale adaptive filtering method based on the wavelet TNN is presented for noise reduction in images. The numerical results indicate that the new method outperforms the Wiener filter and the standard wavelet thresholding denoising method in both peak-signal-to-noise-ratio (PSNR) and visual effect.

关键词： image processing

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Video scouting: An architecture and, system for the integration of multimedia information in personal TV applications

Video scouting: An architecture and, system for the integrat...

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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Jasinschi, RS Dimitrova, N McGee, T Agnihotri, L Zimmerman, J Philips Res Briarcliff Manor NY 10510 USA

ISBN: (纸本)0780370414

Currently available Personal Video Recorders find and store whole TV programs. Our system, Video Scouting, not only finds and stores programs;it automatically segments and indexes story segments from the programs according to viewers' profiles. The extracted descriptions serve the viewers' content information requests for program segment selection, e.g. play the three minute interview with Hillary Clinton. To achieve this, the system combines information from the audio, visual, and transcript domains in a probabilistic framework based on Bayesian networks. In this paper we describe the overall architecture, a system implementation, and discuss some experimental results.

关键词： image retrieval

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Efficient implementation of video post-processing algorithms on the BOPS parallel architecture

Efficient implementation of video post-processing algorithms...

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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Petrescu, D BOPS Inc Chapel Hill NC 27514 USA

ISBN: (纸本)0780370414

Deblocking and deringing are two video post-processing techniques largely used to remove coding artifacts and improve the visual quality when rendering low bit rate coded video. The algorithms used to achieve these tasks are computationally intensive and usually require high speed processors to be able to run in real time. Efficient implementations of signal adaptive filters for video post-processing can be obtained using the specialized features of the parallel BOPS(R) DSP cores. The performance achieved by deblocking and deringing CIF and SDTV size video sequences on the MANTA(TM) prototype chip are illustrated. It is shown that such complex tasks may be executed at low clock rates using the BOPS ManArray(TM) technology.

关键词： Video signal processing

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Local bandwidth constrained fast inverse motion compensation for DCT-domain video transcoding

Local bandwidth constrained fast inverse motion compensation...

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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Liu, S Bovik, AC Laboratory for Image and Video Eng. Dept. of Elec. and Comp. Engineering The University of Texas at Austin Austin TX 78712-1084 United States

ISBN: (纸本)0780370414

DCT-based digital video coding standards such as MPEG and H.26x are becoming more widely adopted for multimedia applications. Since the standards differ in their format and syntax, video transcoding, where a pre-coded video bit-stream is converted from one format to another format, is of interest for purposes such as channel bandwidth adaptation and video composition. DCT-domain video transcoding is generally more efficient than spatial domain transcoding. However, since the data is organized block by block in the DCT-domain, inverse motion compensation becomes the bottleneck for DCT-domain methods. In this paper, we propose a novel local bandwidth constrained fast inverse motion compensation algorithm operating in the DCT-domain. Relative to Chang's algorithm [1], the proposed algorithm achieves computational improvement of 25% to 55% without visual degradation. A by-product of the proposed algorithm is a reduction of blocking artifacts in very low bit-rate compressed video sequences.

关键词： Motion compensation

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Artifact free signal denoising with wavelets

Artifact free signal denoising with wavelets

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IEEE International Conference on Acoustics, Speech, and Signal processing

作者： Durand, S Froment, J CMLA Ecole Normale Super Cachan F-94235 Cachan France

ISBN: (纸本)0780370414

Recent years have seen the development of signal denoising algorithms based on wavelet transform. It has been shown that thresholding the wavelet coefficients of a noisy signal allows to restore the smoothness of the original signal. However, wavelet denoising suffers of a main drawback : around discontinuities the reconstructed signal is smoothed, exhibiting pseudo-Gibbs phenomenon. We consider the problem of denoising piecewise smooth signals with sharp discontinuities. We propose to apply a traditional wavelet denoising method and to restore the denoised signal using a total variation minimization approach. This second step allows to remove the Gibbs phenomena and therefore to restore sharp discontinuities, while the other structures are preserved. The main innovation of our algorithm is to constrain the total variation minimization by the knowledge of the remaining wavelet coefficients. In this way, we make sure that the restoration process does not deteriorate the information that has been considered as significant in the denoising step. With this approach we substantially improve the performance of classical wavelet denoising algorithms, both in terms of SNR and in terms of visual artifacts.

关键词： Signal processing

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Unequal error protection for foveation-based error resilience over mobile networks

Unequal error protection for foveation-based error resilienc...

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IEEE International Conference on image processing (ICIP 2000)

作者： Lee, S Podilchuk, C Krishnan, V Bovik, AC Lucent Technol Wireless Networks Mt Olive NJ 07828 USA

ISBN: (纸本)0780362985

In this paper, we introduce an unequal error protection technique for foveation-based error resilience over highly error-prone mobile networks. For point-to-point visual communications, visual quality can be significantly increased by using foveation-based error resilience where each frame is divided into foveated and background layers according to the gaze direction of the human eye, and two bitstreams are generated. In an effort to increase the source throughput of foveated layer, we employ unequal delay-constrained ARQ and RCPC (rate compatible punctured convolutional) codes in H.223 Annex C. In the simulation, the visual quality is increased in the range of 0.3 dB to 1 dB over channel SNR 5 dB to 15 dB.

关键词： image communication systems

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国际光学工程学会会议录馆藏新目录

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光机电信息 1998年第3期 46-46页

传真通迅和图像处理’97=visual communications and image processing’97∥***、—1997,***3—2.—689—1012传真通迅和图像处理’97=visual communications and image processing’97∥***.—1997,***3—3.—1013—1452超高分辨率和质量的成像Ⅱ=Very high reslution and quality imagingⅡ∥***.—1997.V.3025.—186非线性图像处理Ⅷ=Nonlinear image processingⅧ∥***.—1997,V3026.—350文件识别Ⅳ=Document recognitionⅣ∥***.—1997,V.3027.

关键词： SPIE ii 线性图像处理医学图像光学工程会议录会议资料馆藏目录检索工具

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Estimating blockness distortion for performance evaluation of picture coding algorithms

Estimating blockness distortion for performance evaluation o...

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1997 IEEE Pacific Rim Conference on communications, Computers and Signal processing

作者： Giusto, DD Perra, M Univ of Cagliari Cagliari Italy

ISBN: (纸本)0780339061

In this paper, some of the most significant image quality indexes are reviewed and compared with a new method for blockness distortion evaluation. The paper begins with a brief survey on classical measures based on numerical difference between original and reconstructed image data (e.g., MSE, SNR and PSNR) and advanced methods aiming at considering the perceptive aspects of image degradation (e.g., Hosaka Plots and other methods based on Human visual System properties like Information Content or Perceptual image Distortion). After, four innovative methods for blockness distortion measurement are proposed: two based on DCT analysis, and two on differential Sobel operator. Results on standard pictures confirm the efficiency of the proposed measures.

关键词： image coding

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