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1st European conference on Colour in Graphics, Imaging and Vision (CGIV 2002)

作者： Le Callet, P Barba, D IRCCyN Nantes France

ISBN: (纸本)0892082399

Color image quantization is very used in several applications of image processing. In this paper, we present an original approach to define quantizers for color images taking into account human visual system properties. As this approach is entirely based on results of psychophysics experiments, we define it as psychovisual quantization. From experiments, we have constructed a model to define the optimal quantization law in various spatial frequency without introducing any visible degradation. This model include three steps: a component decomposition defining a color space, a sub-band decomposition which emulates the frequency tuning of human visual system receptor fields, and finally an adaptation of the quantization law according to the modification of the visibility of a signal depending of its context due to the masking effect. Obtained model is used to define the optimal quantization laws adapted to any color image.

关键词： Color image processing

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Adaptation of vision model based distortion metrics to perceptual image coding 14

Adaptation of vision model based distortion metrics to perce...

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14th International conference on Digital Signal processing (DSP 2002)

作者： Wu, HR Tan, DM Qiu, B Yu, Z Monash Univ Clayton Vic 3168 Australia

ISBN: (纸本)0780375033

Recent research efforts in the development of objective quality and impairment measures for quality assessment of digital video and television have helped to improve and to refine models for the human visual system. In particular, recent publications by Winkler [1], Lubin [2] and Yu et al [3] have incorporated comprehensive vision models as part of their picture quality and impairment metric design. Applications of these vision-model-based perceptual quality or impairment metrics to image/video compression are seen as the next step in delivering perceptual image or video coding systems which cater for improvement in perceived picture quality. This paper subscribes to an approach to perceptual image coder design whereby a vision-model based perceptual distortion metric is introduced into a conventional coder, e.g. JPEG2000 compliant coder, in place of the mean-square-error measure for rate-distortion optimization. Simulation results show that the new perceptual image coder provides better performance over the JPEG2000 coder with or without the visual masking option [4].

关键词： Mean square error

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ρ-domain optimum bit allocation and accurate rate control for DCT video coding

ρ-domain optimum bit allocation and accurate rate control f...

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conference on visual communications and image processing 2002

作者： He, ZH Chen, CW Sarnoff Co Interact Med Grp Princeton NJ 08543 USA

ISBN: (纸本)0819444111

In this research, we have developed a novel and unified rate-distortion (R-D) analysis framework for all standard DCT-based video coding systems, including MPEG-2, H.263, and MPEG-4. Within this framework, we consider the coding bit rate as a function of the percentage of zeros among the quantized DCT coefficients. From our extensive simulations over a wide range of video data, we observe that this rate function appears linear in all standard video coding. Based on Shannon's source coding theorem, we provide a heuristic justification for this linear rate model, which helps us better understand the unique behavior of the video encoder. Within the proposed R-D analysis framework, we have also developed an accurate distortion model. It is expected that this simple yet unified R-D modeling shall have significant impact on various video coding related research and development works, including rate control, bit allocation, joint source and channel coding, and so on. In this work, we have developed a unified bit allocation and rate control algorithm for MPEG-2, H.263 and MPEG-4 video coding. Compared to other rate control algorithms reported in the literature, the proposed algorithm controls the coding bit rate more accurately and robustly. In addition, the coded video quality is significantly improved.

关键词： Video coding Video Distortion Quantization Systems modeling Algorithm development Detection and tracking algorithms Computer programming Control systems image compression

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Conformance test of simple profile MPEG-4 texture decoding

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JOURNAL OF ELECTRONIC IMAGING 2002年第3期11卷 375-380页

作者： Kim, WS Park, IS Park, SH Lee, BU Park, RH Sogang Univ Dept Elect Engn Seoul 100611 South Korea Ewha Womans Univ Dept Informat Elect Seoul 120750 South Korea

Moving picture experts group (MPEG)-4 visual conformance standard specifies methods to verify whether bitstreams and decoders meet the requirements at a specified profile and level. The test of decoders can be divided into two parts: static and dynamic tests. The static test can be performed by comparing images from a decoder under test with those from a reference decoder using various test bitstreams. This paper proposes design methodologies of test bitstreams for a simple profile MPEG-4 texture decoder, and shows experimental results on the discrete cosine transform (DCT) scan type, DC/AC coefficient prediction, inverse quantization, in-, verse DCT and various macroblock-type verifications. (C) 2002 SPIE and IST.

关键词： Quantization Computer programming image processing Multimedia Video Electronics engineering Process control Video processing visualization Mobile communications

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A new framework of CBIR based on KDD 6

A new framework of CBIR based on KDD

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6th International conference on Signal processing

作者： Xing, Q Yuan, BZ No Jiaotong Univ Inst Informat Sci Beijing 100044 Peoples R China

ISBN: (纸本)0780374886

The researching emphases of CBIR (Content-based image Retrieval) was put on the low-level visual feature extraction to resolve the problem of manual annotation for images in recent years. But because of variety of images, the extracted visual features can not express the semantic content of each image correctly. So the retrieval accuracy is lower than the text-based image retrieval accuracy generally. In this paper we propose a new retrieval method based on KDD (Knowledge Discover in Database) and knowledge reasoning to improve the retrieval accuracy, and relate the low-level image features with the high-level semantic content. Experiment shows that the result is much better than the traditional retrieval method.

关键词： Content-based image retrieval KDD Rough set knowledge reasoning

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Robust and edge-preserving video error concealment by coarse-to-fine block replenishment

Robust and edge-preserving video error concealment by coarse...

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IEEE International conference on Acoustics, Speech, and Signal processing

作者： Belfiore, S Crisà, L Grangetto, M Magli, E Olmo, G Politecn Torino Dipartimento Elettr I-10129 Turin Italy

ISBN: (纸本)0780374029

In this paper we propose a novel error concealment algorithm for video transmission over wireless networks potentially subject to packet erasures. In particular, we develop a technique for the replenishment of missing macroblocks, which aims at minimizing the impact of the lost data on the resulting video with respect to the human visual system. The proposed algorithm operates three reconstruction stages at different scales, by first recovering smooth large-scale patterns, then large-scale structures, and finally local edges in the lost macroblock. Experimental results show that the proposed algorithm achieves improved visual quality of the reconstructed frames with respect to other state-of-the-art techniques, as well as better PSNR results.

关键词： video coding visual communication edge detection error correction codes image reconstruction image resolution robust error concealment edge-preserving error concealment video error concealment coarse-to-fine block replenishment video transmission wireless networks packet erasures missing macroblocks human visual system reconstruction stages smooth large-scale patterns large-scale structures local edge recovery visual quality reconstructed frames PSNR

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Lip boundary detection techniques using color and depth information

Lip boundary detection techniques using color and depth info...

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conference on visual communications and image processing 2002

作者： Kim, GM Yoon, SH Kim, JH Hur, GT N Carolina Agr & Tech State Univ Dept Elect Engn Greensboro NC 27411 USA

ISBN: (纸本)0819444111

This paper presents our approach to using a stereo camera to obtain 3-D image data to be used to improve existing lip boundary detection techniques. We show that depth information as provided by our approach can be used to significantly improve boundary detection systems. Our system detects the face and mouth area in the image by using color, geometric location, and additional depth information for the face. Initially, color and depth information can be used to localize the face. Then we can determine the lip region from the intensity information and the detected eye locations. The system has successfully been used to extract approximate lip regions using RGB color information of the mouth area. Merely using color information is not robust because the quality of the results may vary depending on light conditions, background, and the human race. To overcome this problem, we used a stereo camera to obtain 3-D facial images. 3-D data constructed from the depth information along with color information can provide more accurate lip boundary detection results as compared to color only based techniques.

关键词： Laser induced plasma spectroscopy Mouth Skin Facial recognition systems 3D image processing RGB color model Eye Colorimetry Stereoscopic cameras Cameras

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Model-based enhancement of lighting conditions in image sequences

Model-based enhancement of lighting conditions in image sequ...

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conference on visual communications and image processing 2002

作者： Eisert, P Girod, B Stanford Univ Informat Syst Lab Stanford CA 94305 USA

ISBN: (纸本)0819444111

Illumination variability has a considerable influence on the performance of computer vision algorithms or video coding methods. The efficiency and robustness of these algorithms can be significantly improved by removing the undesired effects of changing illumination. In this paper, we introduce a 3-D model-based technique for estimating and manipulating the lighting in an image sequence. The current scene lighting is estimated for each frame exploiting 3-D model information and by synthetic re-lighting of the original video frames. To provide the estimator with surface normal information, the objects in the scene are represented by 3-D shape models and their motion and deformation are tracked over time using a model-based estimation method. Given the normal information, the current lighting is estimated with a linear algorithm of low computational complexity using an orthogonal set of light maps. This results in a small set of parameters which efficiently represent the scene lighting. In our experiments, we demonstrate how this representation can be used to create video sequences with arbitrary new illumination. When encoding a video sequence for transmission over a network, significant coding gains can be achieved when removing the time varying lighting effects prior to encoding. Improvements of up to 3 dB in PSNR are observed for an illumination-compensated sequence.

关键词： lighting enhancement model-based illumination compensation image sequence manipulation

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Novel quadtree image coding technique using edge-oriented classification

Novel quadtree image coding technique using edge-oriented cl...

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conference on visual communications and image processing 2002

作者： Keissarian, F Daemi, MF United Arab Emirates Univ Dept Elect Engn Al Ain U Arab Emirates

ISBN: (纸本)0819444111

A new image compression approach is proposed in which variable block size technique is adopted, using quadtree decomposition, for coding images at low bit rates. In the proposed approach, low-activity regions, which usually occupy large areas in an image are coded with a larger block size and the block mean is used to represent each pixel in the block. A novel classification scheme, which operates based on the distribution of the block residuals is employed to determine whether the processed block is a low-detail or a high-detail block. To preserve edge integrity, a new edge-based coding technique is used to code high-activity regions. In this method, the orientation of edge pattern within a high-activity block will be computed as an aid to the classification. A novel edge-oriented classifier, operating based on the histogram analysis of the pixels' orientations, is also proposed to for edge classification. Each edge block is represented by a set of parameters associated with the pattern appearing inside the block. The use of these parameters at the receiver reduces the cost of reconstruction significantly and exploits the efficiency of the proposed technique. Experiments have been conducted to compare with variance-based quadtree technique, vector quantization-based variable size algorithms, as well as the standard JPEG. Results show higher PSNR at competitive reconstruction quality.

关键词： image compression quadtree decomposition edge oriented classifier

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Wavelet picture coding and its several problems of the application to the interlace HDTV and the ultra-high definition images

Wavelet picture coding and its several problems of the appli...

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IEEE International conference on image processing

作者： Kuge, T NHK Japan Broadcasting Corp Sci & Tech Res Labs Setagaya Ku Tokyo 1578510 Japan

ISBN: (纸本)0780376226

A new image coding method utilizing the wavelet transform, JPEG2000, has been developed. In this report, we consider several types of visual distortion observed in moving HDTV pictures and ultra-high definition pictures compressed by wavelet transform coding, and describe measures to reduce them. So-called "flicker artifacts" are visually decreased by visual weighting and the mechanism is interpreted by Weber's law. The characteristic distortion named "Comb-tooth Artifacts" caused by the combination of subband decomposition and the interlaced TV signal structure is discussed, and a preprocessing method is proposed to counter it. The relation between the resolution levels of the subband decomposition and the distortion is investigated by coding experiments on ultra-high definition pictures.

关键词： image coding

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