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Multimedia Tools Appl. 01/2012; 56:385-417.
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ABSTRACT: Novel distributed video coding (DVC) architectures developed by the IBBT DVC group realize state-of-the-art video coding efficiency under stringent energy restrictions, while supporting error-resilience and scalability. Therefore, these architectures are particularly attractive for application scenarios involving low-complexity energy-constrained wireless visual sensors. This demo presents the scenarios, which are considered to be the most promising areas of integration for IBBT's DVC systems, considering feasibility and commercial applicability.
2011 Fifth ACM/IEEE International Conference on Distributed Smart Cameras, Ghent, Belgium, Aug. 22-25, 2011; 01/2011
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18th IEEE International Conference on Image Processing, ICIP 2011, Brussels, Belgium, September 11-14, 2011; 01/2011
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Proceedings of the 2011 IEEE International Conference on Multimedia and Expo, ICME 2011, 11-15 July, 2011, Barcelona, Catalonia, Spain; 01/2011
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ABSTRACT: Recent advances in wireless visual sensor technology, have been calling for innovative architectures realizing efficient video coding under stringent processing and energy restrictions. Driven by profound findings in network information theory, Wyner-Ziv video coding constitutes a suitable paradigm for video sensor networks. This work presents a novel hash-driven Wyner-Ziv video coding architecture for visual sensors, which coarsely encodes a low resolution version of each Wyner-Ziv frame to facilitate accurate motion-compensated prediction at the decoder. The proposed method for side-information generation comprises hash-based multi-hypothesis pixel-based prediction. Once critical Wyner-Ziv information is decoded, the derived dense motion field is further enhanced. Experimental validation illustrates that the proposed hash-driven codec achieves significant compression gains with respect to state-of-the-art Wyner-Ziv video coding, even under demanding conditions.
2011 Fifth ACM/IEEE International Conference on Distributed Smart Cameras, Ghent, Belgium, Aug. 22-25, 2011; 01/2011
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ABSTRACT: The distributed video coding (DVC) paradigm constitutes a flexible framework where computational complexity can be freely distributed between encoder and decoder, hence favoring up-link oriented video applications where recording devices are modest in terms of computational power and are faced with energy consumption constraints. This contribution presents an original transform domain DVC architecture, which performs hash-based motion estimation at the decoder combined with a novel probabilistic motion compensation technique to generate side information. The proposed probabilistic motion compensation incorporates knowledge of the correlation channel statistics and extracts additional information from the hash. Experimental results report Bjontegaard rate savings of up to 4.61%, when using the novel probabilistic motion compensation method instead of our previous approach. Moreover, the compression performance of the presented DVC architecture, featuring the proposed probabilistic motion compensation, surpasses the performance of the state-of-the-art DISCOVER codec, showing Bjontegaard rate savings of up to 15.69%.
2011 Fifth ACM/IEEE International Conference on Distributed Smart Cameras, Ghent, Belgium, Aug. 22-25, 2011; 01/2011
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ABSTRACT: As a result of the consumer’s increasing demand for better quality and higher resolutions, the transit to television broadcasting
in HD, with a resolution of at least 1280 × 720 pixels has recently started to take shape. In this respect, an important challenge
is the selection of a suitable format for recording and production of HD material. One of the issues is that high definition,
unlike standard definition, is quite an ambiguous term. In the first phase of HD television broadcasting deployment, two different
formats were put forward: 720p50/59.94/60 or 1080i25/29.97/30. In the first part of this chapter, the benefits and drawbacks
of both options will be discussed in detail. Besides the choice between 720p and 1080i, the selection of the video compression
format and parameters for HD recording and production is also an important consideration. In this chapter, two state-of-the-art
intra-only compression formats will be reviewed and compared: Motion JPEG 2000 and H.264/AVC Intra. First, an in-depth description
of both video codecs will be provided. Thereafter, the compression schemes will be evaluated in terms of rate-distortion performance,
recompression loss and functionality.
12/2009: pages 137-156;
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10th Workshop on Image Analysis for Multimedia Interactive Services, WIAMIS 2009, London, United Kingdom, May 6-8, 2009; 01/2009
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Advanced Concepts for Intelligent Vision Systems, 8th International Conference, ACIVS 2006, Antwerp, Belgium, September 18-21, 2006, Proceedings; 01/2006
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01/2004
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01/2004
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ABSTRACT: Techniques for full scalability with motion-compensated temporal filtering (MCTF) in the wavelet-domain (in-band) are presented in this paper. The application of MCTF in the wavelet domain is performed after the production of the overcomplete discrete wavelet transform from the critically-sampled decomposition, a process that occurs at both the encoder and decoder side. This process, which is a complete-to-overcomplete discrete wavelet transform, is critical for the efficiency of the system with respect to scalability, coding performance and complexity. We analyze these aspects of the system and set the necessary constraints for drift-free video coding with in-band MCTF. As a result, the proposed architecture permits the independent operation of MCTF within different resolution levels or even different subbands of the transform and allows the successive refinement of the video information in resolution, frame-rate and quality.
07/2003;
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ABSTRACT: Several techniques based on the three-dimensional (3-D) discrete cosine transform (DCT) have been proposed for volumetric data coding. These techniques fail to provide lossless coding coupled with quality and resolution scalability, which is a significant drawback for medical applications. This paper gives an overview of several state-of-the-art 3-D wavelet coders that do meet these requirements and proposes new compression methods exploiting the quadtree and block-based coding concepts, layered zero-coding principles, and context-based arithmetic coding. Additionally, a new 3-D DCT-based coding scheme is designed and used for benchmarking. The proposed wavelet-based coding algorithms produce embedded data streams that can be decoded up to the lossless level and support the desired set of functionality constraints. Moreover, objective and subjective quality evaluation on various medical volumetric datasets shows that the proposed algorithms provide competitive lossy and lossless compression results when compared with the state-of-the-art.
IEEE Transactions on Medical Imaging 04/2003; 22(3):441-58. · 3.64 Impact Factor
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01/2003
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Visual Communications and Image Processing 2003; 01/2003
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ABSTRACT: In this paper a new very low bit-rate video coding scheme is introduced. The scheme uses mesh-based motion estimation to reduce temporal redundancy in the video data and a wavelet-based coding technique to compress the intra-frames and the estimation errors. By using these techniques, the appearance of blocking artifacts at low bit-rates is avoided. This results in superior visual quality compared to that obtained with traditional coding schemes like H.263. Furthermore, the use of wavelet-based coding techniques allows for easier bit-rate control.
11/2001;
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ABSTRACT: In the literature, several rate control techniques have been proposed to aim at the optimal quality of digitally encoded video under given bit budget, channel rate and buffer size constraints. Typically, these approaches are group-of-picture (GOP) based. For longer, heterogeneous sequences, they become unacceptably complex or struggle with model mismatches. In this paper, an off-line segment-based rate control approach is proposed for controlling the distortion variation across successive shots of a video sequence when encoding with single-layer (MPEG-4 baseline, MPEG-4 AVC) and scalable (wavelet) video codecs. Consistent quality is achieved by optimally distributing the available bits among the different segments, based on efficient rate-distortion (R-D) modelling of each segment. The individual segments are defined based on shot segmentation and activity analysis techniques. The algorithm is formulated for three different distribution models: download, progressive download and streaming. The results indicate that the proposed technique improves the quality consistency significantly, while the processing overhead compared to classical two-pass variable bit-rate (VBR) encoding is limited.
Signal Processing: Image Communication.
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ABSTRACT: In this paper a new very low bit-rate video coding scheme is introduced. The scheme uses mesh-based motion estimation to reduce temporal redundancy in the video data and a wavelet-based coding technique to compress the intra-frames and the estimation errors. By using these techniques, the appearance of blocking artifacts at low bit-rates is avoided. This results in superior visual quality compared to that obtained with traditional coding schemes like H.263. Furthermore, the use of wavelet-based coding techniques allows for easier bit-rate control.
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ABSTRACT: An off-line shot-based rate control approach is proposed for controlling the distortion variation across successive shots of a video sequence when encoding with single-layer (MPEG-4 Baseline, MPEG-4 AVC, Windows Media 9) and scalable (wavelet) video codecs. Consistent quality is achieved by optimally distributing the available bits among the different shots, based on rate-distortion modeling of each shot. The algorithm is formulated for the download and progressive download distribution model. The method can be applied to any codec. To evaluate the performance of the algorithm, a video sequence consisting of several shots is encoded with state-of-the-art video codecs using standard rate control and using our proposed method. The quality consistency in both cases is thereafter compared based on the PSNR of the luminance component. The results indicate that the proposed technique improves the quality consistency significantly.
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ABSTRACT: Video transmission over variable-bandwidth networks requires instantaneous bit-rate adaptation at the server site to provide an acceptable decoding quality. For this purpose, recent developments in video coding aim at providing a fully embedded bit-stream with seamless adaptation capabilities in bit-rate, frame-rate and resolution. A new promising technology in this context is wavelet-based video coding. Wavelets have already demonstrated their potential for quality and resolution scalability in still-image coding. This led to the investigation of various schemes for the compression of video, exploiting similar principles to generate embedded bit-streams. In this paper we present scalable wavelet-based video-coding technology with competitive rate-distortion behavior compared to standardized non-scalable technology.
