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Silhouette and stereo fusion for 3D object modeling

COMPUTER VISION AND image UNDERSTANDING 2004年第3期96卷 367-392页

作者： Esteban, CH Schmitt, F Signal and Image Processing Department CNRS UMR 5141 Ecole Nationale Supérieure des Télécommunications France

In this paper, we present a new approach to high quality 3D object reconstruction. Starting from a calibrated sequence of color images, the algorithm is able to reconstruct both the 3D geometry and the texture. The core of the method is based on a deformable model, which defines the framework where texture and silhouette information can be fused. This is achieved by defining two external forces based on the images: a texture driven force and a silhouette driven force. The texture force is computed in two steps: a multi-stereo correlation voting approach and a gradient vector flow diffusion. Due to the high resolution of the voting approach a multi-grid version of the gradient vector flow has been developed. Concerning the silhouette force, a new formulation of the silhouette constraint is derived. It provides a robust way to integrate the silhouettes in the evolution algorithm. As a consequence, we are able to recover the contour generators of the model at the end of the iteration process. Finally, a texture map is computed from the original images for the reconstructed 3D model. (C) 2004 Elsevier Inc. All rights reserved.

关键词： 3D reconstruction deformable model multigrid gradient vector flow visual hull texture

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Block based embedded color image and video coding

Block based embedded color image and video coding

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Conference on visual communications and image processing 2004

作者： Nagaraj, N Pearlman, WA Islam, A GE Global Res John F Welch Technol Ctr Bangalore Karnataka India

ISBN: (纸本)0819452114

Set Partitioned Embedded bloCK coder (SPECK) has been found to perform comparable to the best-known still grayscale image coders like EZW, SPIHT, JPEG2000 etc. In this paper, we first propose Color-SPECK (CSPECK), a natural extension of SPECK to handle color still images in the YUV 4:2:0 format. Extensions to other YUV formats are also possible. PSNR results indicate that CSPECK is among the best known color coders while the perceptual quality of reconstruction is superior than SPIHT and JPEG2000. We then propose a moving picture based coding system called Motion-SPECK with CSPECK as the core algorithm in an intra-based setting. Specifically we demonstrate two modes of operation of Motion-SPECK, namely the constant-rate mode where every frame is coded at the same bit-rate and the constant-distortion mode, where we ensure the same quality for each frame. Results on well-known CIF sequences indicate that Motion-SPECK performs comparable to Motion-JPEG2000 while the visual quality of the sequence is in general superior. Both CSPECK and Motion-SPECK automatically inherit all the desirable features of SPECK such as embeddedness, low computational complexity, highly efficient performance, fast decoding and low dynamic memory requirements. The intended applications of Motion-SPECK would be high-end and emerging video applications such as High Quality Digital Video Recording System, Internet Video, Medical Imaging etc.

关键词： image coding video coding compression color coding embedded Motion-JPEG2000 wavelet intra-based coding moving picture coding

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Geometric model-based segmentation of the prostate and surrounding structures for image guided radiotherapy

Geometric model-based segmentation of the prostate and surro...

引用

Conference on visual communications and image processing 2004

作者： Tang, XL Jeong, YW Radke, RJ Chen, GTY Rensselaer Polytech Inst ECSE Dept Troy NY 12180 USA

ISBN: (纸本)0819452114

We present a computer vision tool to improve the clinical outcome of patients undergoing radiation therapy for prostate cancer by improving irradiation technique. While intensity modulated radiotherapy (IMRT) allows one to irradiate a specific region in the body with high accuracy, it is still difficult to know exactly where to aim the radiation beam on every day of the 30similar to40 treatments that are necessary. This paper presents a geometric model-based technique to accurately segment the prostate and other surrounding structures in a daily serial CT image, compensating for daily motion and shape variation. We first acquire a collection of serial CT scans of patients undergoing external beam radiotherapy, and manual segmentation of the prostate and other nearby structures by radiation oncologists. Then we train shape and local appearance models for the structures of interest. When new images are available, an iterative algorithm is applied to locate the prostate and surrounding structures automatically. Our experimental results show that excellent matches can be given to the prostate and surrounding structure. Convergence is declared after 10 iterations. For 256 x 256 images, the mean distance between the hand-segmented contour and the automatically estimated contour is about 1.5 pixels (2.44 mm), with variance about 0.6 pixel (1.24 mm).

关键词： shape model appearance model principal component analysis segmentation intensity modulated radiotherapy conformal avoidance

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Robust image transmission using a new joint source channel coding algorithm and dual adaptive OFDM

Robust image transmission using a new joint source channel c...

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Conference on visual communications and image processing 2004

作者： Masoud, F Cho, S Pearlman, WA Rensselaer Polytech Inst Ctr Image Proc Res Dept Elect Comp & Syst Engn Troy NY 12180 USA

ISBN: (纸本)0819452114

In this paper we consider the problem of robust image coding and packetization for the purpose of communications over slow fading frequency selective channels and channels with a shaped spectrum like those of digital subscribe lines (DSL). Towards this end, a novel and analytically based joint source channel coding (JSCC) algorithm to assign unequal error protection is presented. Under a block budget constraint, the image bitstream is de-multiplexed into two classes with different error responses. The algorithm assigns unequal error protection (UEP) in a way to minimize the expected mean square error (MSE) at the receiver while minimizing the probability of catastrophic failure. In order to minimize the expected mean square error at the receiver, the algorithm assigns unequal protection to the value bit class (VBC) stream. In order to minimizes the probability of catastrophic error which is a characteristic of progressive image coders, the algorithm assigns more protection to the location bit class (LBC) stream than the VBC stream. Besides having the advantage of being analytical and also numerically solvable. the algorithm is based on a new formula developed to estimate the distortion rate (D-R) curve for the VBC portion of SPIHT. The major advantage of our technique is that the worst case instantaneous minimum peak signal to noise ratio (PSNR) does not differ greatly from the averge MSE while this is not the case for the optimal single stream (UEP) system. Although both average PSNR of our method and the optimal single stream UEP are about the same, our scheme does not suffer erratic behavior because we have made the probability of catastrophic error arbitarily small. The coded image is sent via orthogonal frequency division multiplexing (OFDM) which is a known and increasing popular modulation scheme to combat ISI (Inter Symbol Interference) and impulsive noise. Using dual adaptive energy OFDM, we use the minimum energy necessary to send each bit stream at a part

关键词： SPIHT OFDM robust image transmission

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Effective quality analysis for video streaming over wireless ad hoc network

Effective quality analysis for video streaming over wireless...

引用

Conference on visual communications and image processing 2004

作者： He, ZH Chen, CW Univ Missouri Dept Elect & Comp Engn Columbia MO 65211 USA

ISBN: (纸本)0819452114

Video encoding and streaming over wireless ad hoc network operates under severe conditions, such as time-varying channel characteristics with bursty errors, limit power for data transmission, and dynamic topology of the self-organized network, stringent time delay for packet delivery, etc. Due to the dynamic topology, complex mechanism, and time-varying nature of the wireless ad hoc network, the network system and the streaming service often exhibit unpredictable behaviors. The ultimate goal in the wireless video streaming service is to provide the end user with the best possible video presentation quality. The video streaming quality, often measured by the end-to-end picture distortion, is affected by the scene coding characteristics S of the input video, and the configuration of the network parameters N which includes bandwidth, transmission power, bit error ratio, delay, etc. This brings up the following important and challenging issue: given an input video with scene characteristics S and a network configuration N, what is the average video streaming quality the receiver could expect the system to provide. To address this issue, in this work, we examine the behaviors and constraints of the major components in the streaming system, and propose an across-layer framework to model, control, and optimize the end-to-end video streaming quality.

关键词： Video Video coding Video compression Distortion Data modeling Video surveillance Computer programming Wireless communications Statistical analysis Data transmission

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Selective Bayesian estimation for efficient super-resolution

Selective Bayesian estimation for efficient super-resolution

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Fourth IEEE International Symposium on Signal processing and Information Technology, ISSPIT 2004

作者： Ivanovski, Zoran A. Karam, Lina J. Abousleman, Glen P. Department of Electrical Engineering Arizona State Univesity Tempe AZ 85287-5706 Compression Communications and Intelligence Lab. General Dynamics C4 Systems Scottsdale AZ 85257

ISBN: (纸本)0780386892

In this paper, a new approach to efficient and robust super-resolution is presented. Our method is based on selectively applying a Bayesian MAP estimator to image regions with high spatial activity. The degree of spatial activity is measured using the gradient of the estimated high-resolution image at each iteration. In addition, selective filtering is applied to enhance the visual quality of the estimated high-resolution image. The results obtained via simulation and with real video sequences demonstrate up to a 50% reduction in computational complexity, with improved visual quality, and higher SNR gains for magnification factors of four or more. © 2004 IEEE.

关键词： image analysis

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Lossless compression for three-dimensional images

Lossless compression for three-dimensional images

引用

Conference on visual communications and image processing 2004

作者： Tang, XL Pearlman, WA Rensselaer Polytech Inst ECSE Dept Troy NY 12180 USA

ISBN: (纸本)0819452114

We investigate and compare the performance of several three-dimensional (3D) embedded wavelet algorithms on lossless 3D image compression. The algorithms are Asymmetric Tree Three-Dimensional Set Partitioning In Hierarchical Trees (AT-3DSPIHT), Three-Dimensional Set Partitioned Embedded bloCK (3D-SPECK), Three-Dimensional Context-Based Embedded Zerotrees of Wavelet coefficients (3D-CB-EZW), and JPEG2000 Part II for multi-component images. Two kinds of images are investigated in our study -8-bit CT and MR medical images and 16-bit AVIRIS hyperspectral images. First, the performances by using different size of coding units are compared. It shows that increasing the size of coding unit improves the performance somewhat. Second, the performances by using different integer wavelet transforms are compared for AT-3DSPIHT, 3D-SPECK and 3D-CB-EZW. None of the considered filters always performs the best for all data sets and algorithms. At last, we compare the different lossless compression algorithms by applying integer wavelet transform on the entire image volumes. For 8-bit medical image volumes, AT-3DSPIHT performs the best almost all the time, achieving average of 12% decreases in file size compared with JPEG2000 multi-component, the second performer. For 16-bit hyperspectral images, AT-3DSPIHT always performs the best, yielding average 5.8% and 8.9% decreases in file size compared with 3D-SPECK and JPEG2000 multi-component, respectively. Two 2D compression algorithms, JPEG2000 and UNIX zip, are also included for reference, and all 3D algorithms perform much better than 2D algorithms.

关键词： medical imaging hyperspectral imaging lossless image compression EZW SPIHT JPEG2000

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Power-rate-distortion analysis for wireless video communication under energy constraint

Power-rate-distortion analysis for wireless video communicat...

引用

Conference on visual communications and image processing 2004

作者： He, ZH Liang, YF Ahmad, I Univ Missouri Dept Elect & Comp Engn Columbia MO 65211 USA

ISBN: (纸本)0819452114

In video coding and streaming over wireless communication network, the power-demanding video encoding operates on the mobile devices with limited energy supply. To analyze, control, and optimize the rate-distortion (R-D) behavior of the wireless video communication system under the energy constraint, we need to develop a power-rate-distortion (P-R-D) analysis framework, which extends the traditional R-D analysis by including another dimension, the power consumption. Specifically, in this paper, we analyze the encoding mechanism of typical video encoding systems and develop a parametric video encoding architecture which is fully scalable in computational complexity. Using dynamic voltage scaling (DVS), a hardware technology recently developed in CMOS circuits design, the complexity scalability can be translated into the power consumption scalability of the video encoder. We investigate the rate-distortion behaviors of the complexity control parameters and establish an analytic framework to explore the P-R-D behavior of the video encoding system. Both theoretically and experimentally, we show that, using this P-R-D model, the encoding system is able to automatically adjust its complexity control parameters to match the available energy supply of the mobile device while maximizing the picture quality. The P-R-D model provides a theoretical guideline for system design and performance optimization in wireless video communication under energy constraint, especially over the wireless video sensor network.

关键词： Video Video coding Computer programming Control systems Motion estimation Distortion Wireless communications Telecommunications Mobile devices Video surveillance

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Temporal layered vs. multi-state video coding

Temporal layered vs. multi-state video coding

引用

Conference on visual communications and image processing 2004

作者： Ekmekci, S Sikora, T Tech Univ Berlin Berlin Germany

ISBN: (纸本)0819452114

Multiple Description Video Coding (MDC) and Layered Coding (LC) are both error-resilient source coding techniques used for transmission over error-prone channels. Both techniques generate multiple streams. The streams generated by MDC correspond to different descriptions of the same source whereas the streams produced by LC are differentiated as base and enhancement layer streams. Moreover whereas the MDC streams are independently decodable the decoding of the enhancement layer stream is dependent on the decoding of the base layer stream. In this work we concentrate on specific MDC and LC schemes, i.e. Multi-State Video Coding (MSVC) and Temporal Layered Coding (TLC). MSVC was introduced in(1) and it was showed that if each frame is transmitted in a separate packet and if motion information for each lost frame is also lost, MSVC outperforms Single Layer Coding (SC) in recovering from single as well as burst losses. Here we compared MSVC with TLC as an extension of SC based on transmission simulations over lossy channels under the assumption that the motion vectors are always available. Using different coding modes and specific reconstruction methods average reconstructed frame PSNR (peak signal to noise ratio) is measured and compared. Results show that when motion vectors are received TLC performs better than MSVC for every coding option tested. The performance difference is bigger for low motion sequences.

关键词： layered coding multi-state video coding multiple description coding error-resilient video communications rate allocation Automatic Repeat reQuest (ARQ) error concealment

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Reduction of blocking artifacts in JPEG compressed images

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DIGITAL SIGNAL processing 2007年第1期17卷 225-243页

作者： Singh, Sukhwinder Kumar, Vinod Verma, H. K. Indian Inst Technol Dept Elect Engn Instrumentat & Signal Proc Lab Roorkee 247667 Uttar Pradesh India

image compression is a very important issue for several applications in the area of multimedia communications, the objective being reduction of storage and transmission costs. Many efficient coding techniques have been developed for various applications. Amongst them, the Joint Photographic Experts Group (JPEG) has been recommended for compression of continuous tone still images. However, the reconstructed images from JPEG compression produce annoying blocking artifacts near block boundaries, particularly in highly compressed images, because each block is transformed and quantized independently. Several techniques/algorithms have been proposed by researchers, both in spatial and frequency domains, for reduction of these artifacts with varied degree of success. These are briefly overviewed here. A new technique working in frequency domain, is proposed here by authors. This paper puts forth a method and an algorithm, working in frequency domain, for the detection and reduction of such blocking artifacts. These artifacts are modeled here as 2-D step functions between two neighboring blocks. Presence of the blocking artifacts is detected by using block activity based on human visual system (HVS) and block statistics. The boundary regions between blocks are identified as either smooth or non-smooth regions. The blocking artifacts in smooth regions are removed by modifying a few DCT coefficients appropriately, whilst an edge-preserving smoothing filter is applied to the non-smooth regions, i.e., genuine edges. The algorithm has been applied to variety of JPEG compressed images and results are compared with other postprocessing algorithms. The reduction in the blocking artifacts for each image have been evaluated using three indices, namely peak signal-to-noise ratio (PSNR), mean structure similarity (MSSIM) index based on human visual perception, and a new index, called here block boundary measure (BBM), applied to both vertical and horizontal block boundaries. The result

关键词： image compression blocking artifacts image quality human visual perception

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