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Visual Communications and Image Processing (VCIP), 2011 IEEE

Date 6-9 Nov. 2011

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Displaying Results 1 - 25 of 147
  • [Front cover]

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  • Organizing committee

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  • Session index

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  • Table of contents

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  • Reviewer committee members

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  • Author index

    Page(s): 1 - 33
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  • Context-based adaptive zigzag scanning for image coding

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (455 KB) |  | HTML iconHTML  

    Coefficient scanning plays an important role in block-based image and video coding standards, such as JPEG, MPEG, and the latest H.264/AVC. In these coding standards, the zigzag scanning method is used for image / frame coding and the field scanning method is used for field coding. Although these scanning methods can achieve acceptable coding efficiency, they do not take the statistical properties of the quantized coefficients of each block into consideration. Therefore, coding redundancy still exists. In this paper, we propose a novel adaptive zigzag scanning scheme, which is called the context-based adaptive coefficient scanning method, and apply it in the lossy JPEG baseline algorithm. Simulation results show that our proposed method achieves better coding efficiency than both the conventional zigzag scanning method and the two-stage zigzag scanning (TSZS) method adopted in JPEG. View full abstract»

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  • Improved rate-adaptive codes for Distributed Video Coding

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (286 KB) |  | HTML iconHTML  

    Distributed Video Coding (DVC) is a coding paradigm which shifts the major computational intensive tasks from the encoder to the decoder. Temporal correlation is exploited at the decoder by predicting the Wyner-Ziv (WZ) frames from the adjacent key frames. Compression is then achieved by transmitting just the parity information required to correct the predicted frame and recover the original frame. This paper proposes an algorithm which identifies most of the unreliable bits in the predicted bit planes, by considering the discrepancies in the previously decoded bit plane. The design of the used Low Density Parity Check (LDPC) codes is then biased to provide better protection to the unreliable bits. Simulation results show that, for the same target quality, the proposed scheme can reduce the WZ bit rates by up to 7% compared to traditional schemes. View full abstract»

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  • Adaptive raster scan for slice/frame coding

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2152 KB) |  | HTML iconHTML  

    In this paper, new raster scan orders other than the conventional horizontal scan from the top-left corner of the image/slice are proposed to fully exploit content correlation from the regions right to and below the current coding unit. By being applied to each slice/frame adaptively with the conventional one, features influencing the scan order selection are investigated. Different adaptive scan schemes are tested and compared. Up to 3.4% bit-rate reduction can be achieved for Intra coding with limited increase in complexity. View full abstract»

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  • Video deblurring algorithm using an adjacent unblurred frame

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (739 KB) |  | HTML iconHTML  

    Blurred frames may sparsely exist in a video sequence acquired by digital camcorder or digital camera. In order to remove the visually annoying artifact due to those blurred frames, this paper presents a novel motion deblurring algorithm where a blurred frame can be reconstructed utilizing adjacent unblurred frames. Firstly, a motion-compensated predictor of the blurred frame is derived from its neighboring unblurred frame using motion estimation. Then, an accurate blur kernel, which is difficult to obtain from a single blurred frame, is computed using both the predictor and the blurred frame. Next, again using those both frames, a residual deconvolution is proposed to reduce ringing artifacts inherent to conventional deconvolution. Simulation results show that the proposed algorithm provides superior deblurring results over conventional deblurring algorithms while preserving details with reduced ringing artifacts. View full abstract»

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  • Content-adaptive encoder optimization of the H.264/AVC deblocking filter for visual quality improvement

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (850 KB) |  | HTML iconHTML  

    This paper presents a new self-adapting and content-sensitive optimization technique for the H.264/AVC in-loop deblocking filter [1], focussing on the visual enhancement of the perceived reconstruction quality. Performed frame-wisely at the encoder side, the proposed algorithm first identifies visually important image regions in the currently decoded and blocky frame, including natural and artificial edge areas, and then optimizes the filter inherent threshold decisions, finding the best trade-off between preserving natural and suppressing artificial edges. As fast optimization criterion, the low complex Edge-PSNR [2] is employed, which has proved a very good congruence to the human visual quality sensation, much better than standard PSNR. In this work, the optimization behavior of all thresholds is analyzed, showing their mostly good-natured curve shape for convex optimization, but high content dependency of the optimal values. The in-loop coding results for AVC evidence the approach's high capability for visual improvement, whose general design is easily portable to other AVC deblocking based architectures like HEVC. View full abstract»

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  • Fast disparity estimation for Multi-view plus depth video coding

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (339 KB) |  | HTML iconHTML  

    Disparity estimation is used in Multi-view Video Coding (MVC) to remove the inter-view redundancies present in both color and depth multi-view video sequences. The standard H.264/MVC achieves high compression efficiency by deriving the optimal disparity vector through the exhaustive calculation of the Rate-Distortion cost function for all the possible search points. This makes disparity estimation highly computational expensive. This paper proposes an efficient technique that exploits both the multi-view and the epipolar geometries to determine the optimal search area, resulting in a reduction of search points and thus computations. Simulation results show that this technique can save up to 95% of the computational cost for disparity estimation, with negligible loss in coding efficiency for both the color and the depth multi-view video coding. View full abstract»

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  • Towards quality-oriented scheduling for live swarm-based P2P streaming

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1508 KB) |  | HTML iconHTML  

    During recent years, the success of live swarm-based P2P streaming system has been witnessed. Nevertheless, how to design an effective mechanism for mitigating video quality degradation in a lossy network environment is still not thoroughly resolved yet. Unlike conventional client-server paradigm, there is data availability problem in swarm-based P2P streaming system. If we directly conduct the importance-first scheduling strategy (i.e. let the chunks with most distortion-rate efficiency get scheduled first) in swarm-based P2P streaming system, the serious content bottleneck for low priority chunks occurs, particularly when the population size is large. To cope with the above issue, in this work, we propose a dynamic strategy-switching approach that combines the advantages of random scheduling and importance-first scheduling. Our simulation results indicate that compared with existing approaches our approach not only provides better scheduling efficiency, but also is scalable even if population size is large. View full abstract»

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  • Real-time forward error correction for video transmission

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    When the video streams are transmitted over the unreliable networks, forward error correction (FEC) codes are usually used to protect them. Reed-Solomon codes are block-based FEC codes. On one hand, enlarging the block size can enhance the performance of the Reed- Solomon codes. On the other hand, large Reed-Solomon block size leads to long delay which is not tolerable for real-time video applications. In this paper a novel approach is proposed to improve the performance of Reed-Solomon codes. With the proposed approach, more than one video frame are encompassed in the Reed-Solomon coding block yet no delay is introduced. Experimental results show that the proposed approach outperforms other real-time error resilient video coding technologies. View full abstract»

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  • Quantitative assessment of 2D versus 3D visualisation modalities

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1233 KB) |  | HTML iconHTML  

    Despite the growth of stereoscopic technology, there has been very little research done into the quantitative benefits of 3D over 2D visualisation systems. This study seeks to quantify and compare the human brain's response to 2D versus 3D images using EEG technology, in particular focusing on the trend in changes between the p300 response resulting from 2D and 3D stimulus sequences using the oddball paradigm. It was found that the p300 response to the 3D stimuli degraded at a faster rate than the 2D stimuli as target spotting task difficulty was raised. View full abstract»

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  • Image matting based on mutual information

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1759 KB) |  | HTML iconHTML  

    In this paper, we propose a novel framework to solve the image matting problem. We design a temporary image based on the estimated foreground and background colors for unknown pixels as well as an initial matte. The similarity of the temporary image and original image is modeled as an energy function in the Markov Random Field (MRF). The global optimized matte is obtained by minimizing the energy function. Therefore, image matting is converted to how to maximize the similarity of the original image and the temporary image. The experiments demonstrate that the proposed method could produce high quality mattes and it is also more effective compared to other top ranking methods. View full abstract»

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  • Priority pyramid based bit allocation for multiview video coding

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (817 KB) |  | HTML iconHTML  

    In Multivew Video Coding (MVC), Hierarchial B Pictures (HBP) structure is adopted to remove the redundancy of multiview videos. It makes the rate control of MVC more difficult with respect to accurate bit control and good compression efficiency. The existing rate control algorithms of MVC are based on those of monoview video coding standards, which didn't exploit the correlations of multiview video frames fully. In this paper, a Group of pictures from multiple views (called GoGOP) are rearranged in the form of a pyramid. The top layer of the pyramid containing anchor frames receives the highest priority in bits consuming. And the next layer is inferior to it but superior to others in bits consuming. Secondly, a matrix of weighting factors is further introduced to perform the bit allocation for MVC. Thirdly, the parameter updating is handled in a vector operation, which is somewhat robust and has a low level of computational complexity. The experimental results demonstrate that our proposed bit allocation cooperating with the conventional rate-distortion (R-D) model in H.264/AVC is efficient in rate control of MVC. The coding performance of the proposed algorithm is comparable to that of hierarchical quantization scheme (HQS) of MVC. Meanwhile, a small bit control error is obtained by our algorithm. View full abstract»

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  • Recognizing human actions using curvature estimation and NWFE-based histogram vectors

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB) |  | HTML iconHTML  

    This paper presents a novel scheme for human action recognition. First of all, we employ the curvature estimation to analyze human posture patterns and to yield the discriminative feature sequences. The feature sequences are further represented into sets of strings. Consequently, we can solve human action recognition problem by the string matching technique. In order to boost the performance of string matching, we apply the Nonparametric Weighted Feature Extraction (NWFE) to compact the string representation. Finally, we train a Bayes classifier to perform action recognition. Unlike traditional approaches using the nearest neighbor rule, our proposed scheme can classify the human actions more efficiently while maintaining high accuracy. The experiment results show that the proposed scheme is efficient and accurate in human action recognition. View full abstract»

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  • Interactive object segmentation using iterative adjustable graph cut

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (593 KB) |  | HTML iconHTML  

    Interactive object segmentation is widely used for extracting any user-interested objects from natural images. A common problem with many interactive segmentation approaches is that the object segmentation quality is degraded due to inaccurate object/background seeds provided by the user. This paper proposes an iterative adjustable graph cut to efficiently solve this problem. First, object/background seeds are initialized based on the object segmentation result obtained with the user-specified scribbles as the interactive input. Then, an iterative seed adjustment scheme is exploited to correct inaccurate seeds and extract new suitable seeds via graph cut, in which the balancing weight between energy terms are adaptively updated to protect stable seeds and speedup the iteration process. Finally, suitable seeds are obtained and graph cut is used to segment the objects. Experimental results demonstrate the better segmentation performance of our approach even if user provides rather rough seeds. View full abstract»

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  • Subjective quality analyses of stereoscopic images in 3DTV system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1942 KB) |  | HTML iconHTML  

    Subjective quality evaluation is the basis of quality evaluation of stereoscopic images. As the lack of a public and diverse testing database currently, in this paper, a symmetric stereoscopic images database is built. And then the subjective quality of stereoscopic images is analyzed from two aspects, one is the effects of JPEG, JPEG2000, H.264. The other is the comparisons between symmetric and asymmetric stereoscopic images from Gaussian blurring, white Gaussian noise, JPEG and JPEG2000, respectively. The results show three compressions are quite different in the subjective quality of symmetric stereoscopic images at different bitrates, and the comparisons between symmetric and asymmetric stereoscopic images investigate the properties of binocular fusion, binocular suppression, and binocular summation. View full abstract»

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  • Unequal channel error protection of multiple description codes for wireless media streaming

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1219 KB) |  | HTML iconHTML  

    We investigate the problem of optimal channel protection of multiple-description coded (MDC) multimedia contents at a wireless access point (WAP). For each MDC packet, the WAP has the option to protect and broadcast the packet using one of the available channel coders, or to drop the packet altogether. For a fixed FEC-based MDC, we show how this optimization can be approximated by a convex optimization problem with linear constraints, and thus, can be solved efficiently. We verify the validity of our results through ex- tensive simulations of a wireless image streaming application that employs multiple turbo channel coders, where we report gains of more than 2.50 dB PSNR in average reconstruction quality at receivers. We also devise an iterative algorithm for joint optimization of the channel code rate assignment and the design of the MDC. Our simulations show further gains of up to 5.40 dB in average PSNR when this joint optimization is employed. View full abstract»

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  • Recent progress on perceptual video coding

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (702 KB) |  | HTML iconHTML  

    The purpose of this technical demonstration is to show how the compressed video quality can be improved by taking the characteristics of human visual system into account in the rate distortion optimization and rate control processes of a video encoder. Both the R-D performance of the video encoder and the picture quality can be evaluated subjectively by the viewers in this demonstration to witness that perceptual video coding is indeed a promising direction for next generation video coding. View full abstract»

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  • Image indexing using 3D model for image retrieval

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (267 KB) |  | HTML iconHTML  

    Content-based image retrieval (CBIR) is an interesting but difficult topic of research. It uses the visual features to achieve the image searching on database. In this paper, we propose an image indexing for CBIR based on color feature, which consider both the computational complexity and the spatial relationship. We use a 3D mathematical model to design the color codebook and exploit the feature of the query image to adopt it. In the experiments, we discuss the three parameters affecting the performance and find out the corresponding optimal value to raise the retrieval speed and accuracy. Besides, we also demonstrate that the proposed scheme is robust for some image distortions and best matches human perception overall. View full abstract»

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  • Compressive sensing based video scrambling for privacy protection

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5502 KB) |  | HTML iconHTML  

    Surveillance video privacy protection has drawn significant attention recently. In this paper, we describe a privacy protected video surveillance system which utilizes the emerging compressive sensing (CS) theory. Privacy regions are scrambled through block based CS sampling on quantized coefficients during compression. Security is ensured by key controlled chaotic sequence which is used to construct CS measurement matrix. To prevent drift error caused by scrambling, a coding restricted scheme is exploited. Experimental results show that the proposed system effectively protects privacy with the scene intelligible. Compared with the existing ones, this system has high security and dramatic coding efficiency improvement. View full abstract»

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  • Real-time multi-camera air surveillance system using a simultaneous estimation, filtering and rejection tracking algorithm

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1275 KB) |  | HTML iconHTML  

    In this paper, we propose an aerial surveillance system utilizing a static camera and a PTZ camera. The static camera captures a wide angle view of the scene, while the PTZ camera is capable of zooming in to a region of interest (ROI) selected by the user and capturing a detailed image. The system consists of a novel tracking algorithm named Simultaneous Estimation, Filtering and Rejection (SEFAR) and a multi- camera apparatus accommodating real-time requirements. The SEFAR algorithm performs feature point detection, homography estimation and outlier rejection in a one-pass process, avoiding time consuming iterations. The multi-camera apparatus uses high-resolution cameras of different zoom factors with a rotatable mirror for faster PTZ movements. Experimental results show robust and efficient tracking performance of SEFAR, demonstrating its possible use in real aerial surveillance systems in the future. View full abstract»

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