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IEEE International conference on image processing

作者： Mayer, J UFSC Dept Elect Engn LPDS Florianopolis SC Brazil

ISBN: (纸本)0780376226

A non-iterative post-processing enhancement technique is proposed for images degraded by either the JPEG-DCT or the JPEG-LS (LOCO) lossy coding algorithm. A degraded image is classified into active and smooth regions. A distance transform is applied to the resulting classification, and is used to determine the size and order of a Bezier surface patch. These Bezier blending surfaces, built with Bernstein polynomials, provide an interesting representation for the image. This approach mitigates the quantization noise while preserving strong edges and textures. Results illustrate the significant visual improvement achieved with a computational complexity of O(n).

关键词： image enhancement

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Rate-distortion model based rate control for real-time VBR video coding and low-delay communications

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SIGNAL processing-image COMMUNICATION 2002年第2期17卷 187-199页

作者： Bai, JF Liao, QM Lin, XG Zhuang, XH Univ Missouri Dept Comp Engn & Comp Sci Multimedia Commun & Visualisat Lab Columbia MO 65211 USA Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China

Rate control is an important component in a video encoder for data storage or real-time visual communications, In the paper, we will discuss the rate control in MPEG encoder for low-delay real-time video communications over variable bit-rate (VBR) channel, In low-delay video communications, the video transmission is subject not only to the channel rate constraints, but also to the end-to-end delay constraints. In the paper, we employ leaky-bucket model to describe the traffic parameters and monitor the encoder's output. First, an ad hoc bit-allocation method is introduced. Although satisfying the rate constraints perfectly, it provides the objective quality of the decoded image to be just comparable to that of CBR rate control using MPEG2 TM5. Then, a new rate-distortion model is developed, based on which an advanced rate control algorithm is designed, producing almost uniform distortion within a frame as well as consistent video quality between frames, Experimental results show that, when compared to both the MPEG2 TM5 and the proposed ad hoc bit-allocation method, the advanced rate control algorithm maintains not only a constant buffer delay, but also a stable decoded image quality in the scenario of VBR transmission. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： VBR video coding rate control rate-distortion model low-delay video communications ATM

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The statistics of visual representation

The statistics of visual representation

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conference on visual Information processing XI

作者： Jobson, DJ Rahman, ZU Woodell, GA NASA Langley Res Ctr Hampton VA 23681 USA

ISBN: (纸本)0819444863

The experience of retinex image processing has prompted us to reconsider fundamental aspects of imaging and image processing. Foremost is the idea that a good visual representation requires a non-linear transformation of the recorded (approximately linear) image data. Further, this transformation appears to converge on a specific distribution. Here we investigate the connection between numerical and visual phenomena. Specifically the questions explored are: (1) Is there a well-defined consistent statistical character associated with good visual representations? (2) Does there exist an ideal visual image? And (3) what are its statistical properties?.

关键词： image analysis

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An application of multicriteria optimization to multi-factored image quality models

An application of multicriteria optimization to multi-factor...

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conference on visual communications and image processing 2002

作者： Macklem, M Simon Fraser Univ Dept Math Burnaby BC V5A 1S6 Canada

ISBN: (纸本)0819444111

This paper discusses a model of combining multiple error factors based on multicriteria optimization. Frequently this involves fitting calculated errors to subjective data, and using the resulting scalar weighting as the single-valued error measure to optimize. Instead of finding a way of optimizing a fixed combination of the different factors, we consider the multiple error measures as a vector-valued function, thus producing data for an optimization problem with multiple objective functions. Applying multiple criteria optimization techniques to the resulting problem can yield a range of potentially optimal weightings for each factor. By adding a degree of freedom by way of the utility function, which describes how strongly each objective function contributes to the optimal weighting, we can remove the dependence on fixed scalar combinations resulting from fixed viewing conditions. Using this model., an end user or compression method designer can adaptively set their own preferred weighting. This paper discusses the relevant multiple criteria optimization theory, and describes our experiments with applying these techniques to the PQS model of Miyahara, Kotani and Algazi, applied to greyscale still images. We also describe how such methods could be generalized to models in which each error measure is described using entire images rather than single factors. These include Osberger's Region-of-Interest map,(1) and Daly's Probability Detection Map.(2)

关键词： multicriteria optimization visible differences predictor domination set utility function decision maker

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Adaptive representation of JPEG 2000 images using header-based processing

Adaptive representation of JPEG 2000 images using header-bas...

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IEEE International conference on image processing

作者： Neelamani, R Berkner, K Rice Univ ECE Dept Houston TX 77005 USA

ISBN: (纸本)0780376226

To bridge the mismatch between the sizes of images and display devices, we present an efficient and automatic algorithm to create an adaptive image representation called SmartNail. Given a digital image and rectangular display frame smaller than the image, we define the SmartNail as an appropriately cropped part of a suitably scaled-down image. We choose the SmartNail-defining parameters - down-scaling factor and cropping location - to maximize a bit-allocation-based cost function that quantifies the visual importance of the image content in the SmartNail. For JPEG 2000-encoded images, the SmartNail parameters can be determined using just the header information available in the encoded file. Hence only the wavelet coefficients required to reconstruct the SmartNail need to be decoded from the entire JPEG 2000 code stream. Consequently, the SmartNail construction requires minimal computations and memory requirements. Simulations demonstrate the effectiveness of SmartNail representations.

关键词： image compression

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Automatic threshold determination of centroid-linkage region growing by MPEG-7 dominant color descriptors

Automatic threshold determination of centroid-linkage region...

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IEEE International conference on image processing

作者： Porikli, F Mitsubishi Elect Res Labs Murray Hill NJ 07974 USA

ISBN: (纸本)0780376226

The emerging MPEG-7 standard embodies a visual descriptor that will be associated with the dominant colors of an image. In this contribution, a threshold adaptation method for region based image and video segmentation that takes the advantage of the MPEG-7 dominant color descriptor is presented. This method enables assignment of region growing parameters without any low-level processing. In the standard, the dominant colors proposed to be extracted by clustering of color histograms. This property is used to determine color homogeneity that is formulated into Lorentzian-based color distance norm and corresponding thresholds. The proposed algorithm is compared with other region growing algorithms, and results show that the threshold adaptation performs faster and more robust.

关键词： image segmentation

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Dual-band land mine detection using a Bayesian approach

Dual-band land mine detection using a Bayesian approach

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IEEE International conference on Acoustics, Speech, and Signal processing

作者： Svensson, L Lundberg, M Chalmers Dept Signals & Syst Gothenburg Sweden

ISBN: (纸本)0780374029

The main purpose of the paper is to show that significant improvements in infrared land mine detectors can be achieved, by also considering visual wavelength images. A Bayesian approach, based on dual-band data, is presented that incorporates prior knowledge regarding external parameters such as recent weather, burial depth and soil moisture. By noting that most relevant backgrounds render rotationally invariant statistics, a low dimensional parameterization of the noise space is derived. Simulations show the performance of three different detectors;first the standard detector used, the matched filter which correlates the infrared image with the known mine shape;secondly a detector which models the spatial statistics of the infrared background while neglecting the visual wavelength data, and thirdly the proposed detector that exploits the full dual-band space. The second detector outperforms the matched filter, and is significantly improved by also utilizing the visual wavelength image.

关键词： infrared imaging buried object detection image recognition matched filters weapons Bayes methods infrared land mine detectors visual wavelength images Bayesian approach dual-band data prior knowledge weather burial depth soil moisture rotationally invariant statistics low dimensional parameterization noise space matched filter infrared image mine shape spatial statistics

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Robust wavelet-based arbitrary grid detection for MPEG

Robust wavelet-based arbitrary grid detection for MPEG

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IEEE International conference on image processing

作者： Lesellier, E Jung, J Philips Res Labs F-92156 Suresnes France

ISBN: (纸本)0780376226

From, the industrial point of view, image quality is a key-issue. Many post-processing algorithms have been proposed to improve visual quality after the MPEG decoder. Most of them need the precise location of the 8x8 grid, on which blocking effect appears. However, in real-life applications, blocking effect is rarely located on such a basic grid, due to cascaded bit-rate or format transcoding, rescaling, etc., that occur during the acquisition, the compression, the transmission and the display of the video. Consequently, most of these methods see their efficiency largely reduced, or are simply useless. In this paper, a grid detector based on a fine modelization of blocking artifacts in the wavelet domain is proposed. It aims at providing essential information to any post-processing algorithm that requires the position of the grid. Several experiments and reliable subjective tests demonstrate the accuracy of the proposed grid detector, and highlight the added value it yields to a post-processing algorithm in terms of visual quality.

关键词： image compression

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Improved low frequency image adaptive watermarking scheme 6

Improved low frequency image adaptive watermarking scheme

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6th International conference on Signal processing

作者： Taskovski, D Bogdanova, S Bogdanov, M Univ St Cyril & Methudius Fac Elect Engn Skopje 10000 Macedonia

ISBN: (纸本)0780374886

In this' paper we present extension of our low frequency watermarking scheme. We obtain a robustness improvement to most common image processing operations by embedding the watermark in the. approximation image of the original image. In order to embeds the watermark with minimum loss in image fidelity, the watermark strength is modulated according to the local image characteristics. We generate a visual mask based on the texture, edge and luminance masking effects of the human visual system. Experimental results, show that the proposed technique is competitive with other watermarking techniques.

关键词： image enhancement

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Video indexing using a high-performance and low-computation color-based opportunistic technique

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OPTICAL ENGINEERING 2002年第2期41卷 505-517页

作者： Ahmed, M Karmouch, A Univ Ottawa Sch Informat Technol & Engn Ottawa ON K1N 6N5 Canada

Video information, image processing, and computer vision techniques are developing rapidly because of the availability of acquisition, processing, and editing tools that use current hardware and software systems. However, problems still remain in conveying this video data to the end users. Limiting factors are the resource capabilities in distributed architectures and the features of the users' terminals. The efficient use of image processing, video indexing, and analysis techniques can provide users with solutions or alternatives. We see the video stream as a sequence of correlated images containing in its structure temporal events such as camera editing effects and presents a new algorithm for achieving video segmentation, indexing, and key framing tasks. The algorithm is based on color histograms and uses a binary penetration technique. Although much has been done in this area, most work does not adequately consider the optimization of timing performance and processing storage. This is especially the case if the techniques are designed for use in run-time distributed environments. Our main contribution is to blend high performance and storage criteria with the need to achieve effective results. The algorithm exploits the temporal heuristic characteristic of the visual information within a video stream. It takes into consideration the issues of detecting false cuts and missing true cuts due to the movement of the camera, the optical flow of large objects, or both. We provide a discussion, together with results from experiments and from the implementation of our application, to show the merits of the new algorithm as compared to the existing one. (C) 2002 Society of Photo-Optical Instrumentation Engineers.

关键词： image processing color histogram key frames video indexing video segmentation cut detection binary penetration

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