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Graph-Based Transform for 2D Piecewise Smooth Signals With Random Discontinuity Locations

IEEE TRANSACTIONS ON IMAGE PROCESSING 2017年第4期26卷 1679-1693页

作者： Zhang, Dong Liang, Jie GigPeak Inc Waterloo ON N2V 1C5 Canada Simon Fraser Univ Sch Engn Sci Burnaby BC V5A 1S6 Canada

The graph-based block transform recently emerged as an effective tool for compressing some special signals such as depth images in 3D videos. However, in existing methods, overheads are required to describe the graph of the block, from which the decoder has to calculate the transform via time-consuming eigendecomposition. To address these problems, in this paper, we aim to develop a single graph-based transform for a class of 2D piecewise smooth signals with similar discontinuity patterns. We first consider the deterministic case with a known discontinuity location in each row. We propose a 2D first-order autoregression (2D AR1) model and a 2D graph for this type of signals. We show that the closed-form expression of the inverse of a biased Laplacian matrix of the proposed 2D graph is exactly the covariance matrix of the proposed 2D AR1 model. Therefore, the optimal transform for the signal are the eigenvectors of the proposed graph Laplacian. Next, we show that similar results hold in the random case, where the locations of the discontinuities in different rows are randomly distributed within a confined region, and we derive the closed-form expression of the corresponding optimal 2D graph Laplacian. The theory developed in this paper can be used to design both pre-computed transforms and signal-dependent transforms with low complexities. Finally, depth image coding experiments demonstrate that our methods can achieve similar performance to the state-of-the-art method, but our complexity is much lower.

关键词： Graph-based transform graph laplacian covariance matrix transform coding depth coding

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Analysis of the depth-shift distortion as an estimator for view synthesis distortion

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2016年 41卷 128-143页

作者： Carballeira, Pablo Cabrera, Julian Jaureguizar, Fernando Garcia, Narciso Univ Politecn Madrid ETSI Telecomunicac Grp Tratamiento Imagenes Ciudad Univ E-28040 Madrid Spain

Aiming for 3D Video encoders with reduced computational complexity, we analyze the performance of depth-shift distortion in depth-image based rendering algorithms, incurred when coding depth maps in 3D Video, as an estimator of the distortion of synthesized views. We propose several distortion models that capture (i) the geometric distortion caused by the depth coding error, (ii) the pixel-mapping precision in view synthesis and (iii) the method to aggregate depth-shift distortion caused by the coding error in a depth block. Our analysis starts with the evaluation of the correlation between the depth-shift distortion values obtained with these models, and the actual distortion on synthesized views, with the aim of identifying the most accurate one. The correlation results show that one of the models can be used as a reasonable estimator of the synthesis distortion in low complexity depth encoders. These results also show that the Sum of Absolute Error (SAE) captures better the distortion on a depth block than the Sum of Squared Error (SSE). The correlation analysis is performed at three levels: frame, MB-row and MB. Results show that correlation values are consistently high at the frame level and for most MB-row positions, while lower values are achieved at the MB level and for specific rows at the MB row level. Finally, to assess the results obtained by the correlation analysis, the different depth-shift distortion models are employed in two algorithms of the rate-distortion optimization (RDO) cycle of the depth encoder: (i) Quantization Parameter (QP) selection and (ii) mode decision. We evaluate the QP selection algorithm at three levels: frame, MB row and MB, and the mode decision at the MB level. At the frame level, results show that the use of depth-shift distortion is equivalent to synthesis distortion, with the advantage of a lower computational complexity. At sub-frame levels, the results are consistent with the comparative correlation results, giving guide

关键词： 3D Video depth-image based rendering depth coding Rate-distortion optimization

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FVV Live: A Real-Time Free-Viewpoint Video System With Consumer Electronics Hardware

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IEEE TRANSACTIONS ON MULTIMEDIA 2022年 24卷 2378-2391页

作者： Carballeira, Pablo Carmona, Carlos Diaz, Cesar Berjon, Daniel Corregidor, Daniel Cabrera, Julian Moran, Francisco Doblado, Carmen Arnaldo, Sergio Martin, Maria del Mar Garcia, Narciso Univ Politecn Madrid Grp Tratamiento Imagenes Madrid Spain Univ Autonoma Madrid Escuela Politecn Super Video Proc & Understanding Lab Madrid 28049 Spain Univ Politecn Madrid Grp Tratamiento Imagenes Informat Proc & Telecommun Ctr Madrid 28040 Spain Univ Politecn Madrid ETSI Telecomunicac Madrid 28040 Spain

FVV Live is a novel end-to-end free-viewpoint video system, designed for real-time operation, using consumer-grade cameras and hardware, which enables low deployment costs and easy installation for immersive event-broadcasting or videoconferencing. All the blocks of the system have been designed to maximize perceptual video quality, overcoming the limitations imposed by hardware and network, which impact directly the accuracy of depth data and thus the quality of virtual view synthesis. Therefore, it does not sacrifice perceptual video quality with respect to high-end counterparts. The results presented in this paper correspond to an implementation with nine stereo-based depth cameras. However, the design of the acquisition block of FVV Live allows scalability for an arbitrary number of cameras. In addition, FVV Live presents low motion-to-photon and end-to-end delays, which enables a responsive free-viewpoint navigation and bilateral immersive communications. Moreover, the visual quality of FVV Live has been assessed through subjective assessment with satisfactory results, and additional comparative tests show that it is preferred over state-of-the-art DIBR alternatives.

关键词： Cameras Streaming media Real-time systems Rendering (computer graphics) Bit rate Hardware Servers Visual communications free-viewpoint video consumer electronics multiview video depth coding depth image-based rendering subjective assessment

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Efficient Techniques for depth Video Compression Using Weighted Mode Filtering

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2013年第2期23卷 189-202页

作者： Viet-Anh Nguyen Min, Dongbo Do, Minh N. Adv Digital Sci Ctr Singapore 138632 Singapore Univ Illinois Urbana IL 61820 USA

This paper proposes efficient techniques to compress a depth video by taking into account coding artifacts, spatial resolution, and dynamic range of the depth data. Due to abrupt signal changes on object boundaries, a depth video compressed by conventional video coding standards often introduces serious coding artifacts over object boundaries, which severely affect the quality of a synthesized view. We suppress the coding artifacts by proposing an efficient postprocessing method based on a weighted mode filtering and utilizing it as an in-loop filter. In addition, the proposed filter is also tailored to efficiently reconstruct the depth video from the reduced spatial resolution and the low dynamic range. The down/upsampling coding approaches for the spatial resolution and the dynamic range are used together with the proposed filter in order to further reduce the bit rate. We verify the proposed techniques by applying them to an efficient compression of multiview-plus-depth data, which has emerged as an efficient data representation for 3-D video. Experimental results show that the proposed techniques significantly reduce the bit rate while achieving a better quality of the synthesized view in terms of both objective and subjective measures.

关键词： 3-D video depth coding depth down/upsampling depth dynamic range weighted mode filtering

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Segment-based view synthesis optimization scheme in 3D-HEVC

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JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2017年第Jan.期42卷 104-111页

作者： Dou, Huan Chan, Yui-Lam Ji, Ke-Bin Siu, Wan-Chi Beijing Univ Technol Coll Elect Informat & Control Engn Beijing Peoples R China Hong Kong Polytech Univ Dept Elect & Informat Engn Kowloon Hong Kong Peoples R China

The 3D extension of high efficiency video coding (3D-HEVC) adopts a view synthesis optimization (VSO) technique to improve the quality of synthesized views for depth map coding. The exact synthesized view distortion change (SVDC) is calculated in VSO which in turn brings huge coding complexity to the 3D-HEVC encoder due to the real view synthesis process. This work presents a scheme aimed at reducing coding complexity of the SVDC calculating process in the 3D-HEVC encoder. It skips line segments of pixels with variable lengths based on information from both of the textures and depth maps in the SVDC calculation. Experimental results demonstrate that the proposed scheme can reduce the coding complexity without any significant loss in rate distortion performance for the synthesized views. (C) 2016 Elsevier Inc. All rights reserved.

关键词： 3D-HEVC 3D video coding depth coding View synthesis optimization (VSO) Synthesized view distortion change (SVDC) Early skip mode

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Study of 3D Video Compression Using Nonlinear depth Representation

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IEEE ACCESS 2019年 7卷 31110-31122页

作者： Stankiewicz, Olgierd Wegner, Krzysztof Domanski, Marek Poznan Univ Tech Chair Multimedia Telecommun & Microelect PL-60965 Poznan Poland

The extensions of Advanced Video coding (AVC) and High-Efficiency Video coding (HEVC) for multiview video plus depth allow for the coding of 3D video scenes. During the standardization of these extensions, it was demonstrated that compression performance can often be improved by the application of nonlinear depth transformation prior to the compression and applying the respective backward nonlinear depth transformation after decompression. Such an approach is referred to as the compression of nonlinear depth representation (NDR). In this paper, a survey of the NDR technology is provided, but a large part of this survey comprises yet unpublished results. First, the motivation and rationale behind the idea of NDR are discussed. The options for the choice of nonlinear transformation are provided with the respective formulations. Also, the standardization of 3D video coding with NDR within ISO/IEC and ITU is discussed along with the experimental results that demonstrate benefits related to the application of NDR in 3D-AVC and 3D-HEVC. Furthermore, the experimental comparisons are provided for simulcast coding of multiview plus depth video using AVC and HEVC technology with and without the NDR. The similar experimental results are also provided for simulcast coding using the current version of Versatile Video coding technology that is under development for the forthcoming standard of ISO/IEC (MPEG-I) and ITU. All of the experimental results have been obtained for the standard JVC-3V video test sequences under common test conditions for 3D video coding.

关键词： 3D video 3D-HEVC AVC coding compression depth coding depth representation MVD representation Versatile Video Codec VVC

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Efficient compression of multi-view depth data based on MVC

Efficient compression of multi-view depth data based on MVC

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1st International Conference on 3DTV

作者： Merkle, Philipp Smolic, Aljoscha Mueller, Karsten Wiegand, Thomas Heinrich Hertz Inst Nachrichtentech Berlin GmbH Fraunhofer Inst Telecommun Image Proc Dept D-10587 Berlin Germany

ISBN: (纸本)9781424407217

This paper presents a method for efficient compression of multi-view depth data based on our multi-view video coding approach for color data. The idea is to exploit statistical dependencies from both temporal and inter-view reference pictures for prediction. For this purpose a multi-view video data set including color and depth information is analyzed in terms of coding efficiency. coding experiments using prediction structures with and without inter-view reference pictures are performed with multi-view depth data and compared to multi-view video coding. The results show that additionally applying inter-view prediction to temporal prediction with hierarchical B pictures improves coding efficiency for depth as well as color, reporting average gains in PSNR-Y of 0.5 dB for depth and 0.3 dB for color.

关键词： multiview video depth coding 3D television hierarchical B pictures H.264/AVC

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Adaptive depth Boundary Sharpening for Effective View Synthesis

Adaptive Depth Boundary Sharpening for Effective View Synthe...

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29th Picture coding Symposium (PCS)

作者： Song, Yunseok Lee, Cheon Ho, Yo-Sung Wey, Hocheon Lee, Jaejoon GIST Seoul South Korea Samsung Adv Inst Technol Suwon South Korea

ISBN: (纸本)9781457720482

This paper focuses on sharpening boundaries in depth maps for multi-view video coding. Artifacts around boundaries degrade the quality of synthesized images. In order to encounter this problem, after applying the deblocking filter for each frame, we create a binary edge map and find the location of blocks that need to be altered. Subsequently, we apply a boundary sharpening filter which uses pixel frequency, similarity, and closeness as sub-costs. This filter is only applied to blocks which are near edges. Experimental results exhibit much more visual comfort level in synthesized images compared to when JMVC was used.

关键词： depth coding multi-view video coding view synthesis deblocking filter

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Multiview Video and depth Compression for Free-view Navigation

Multiview Video and Depth Compression for Free-view Navigati...

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Conference on Stereoscopic Displays and Applications XXIII (SD and A)/IS and T/SPIE Electronic Imaging - Science and Technology Symposium

作者： Higuchi, Yuta Tehrani, Mehrdad Panahpour Yendo, Tomohiro Fujii, Toshiaki Tanimoto, Masayuki Nagoya Univ Grad Sch Engn Chikusa Ku Furo Cho Nagoya Aichi 4648603 Japan Nagaoka Univ Technol Dept Elect Engn Nagaoka Niigata 9402188 Japan

ISBN: (纸本)9780819489357

In this paper, we discuss a multiview video and depth coding system for Multiview video applications such as 3DTV and Free View-point Television (FTV)(1). We target an appropriate multiview and depth compression method. And then we investigate the effect on free view synthesis quality by changing the transmission rates between multiview and depth sequences. In the simulations, we employ MVC in parallel to compress the multiview video and depth sequences at different bitrates, and compare the virtual view sequences generated by decoded data with the original video sequences taken in the same viewpoint. Our experimental results show that bitrates of multi depth stream has less effect on the view synthesis quality compared with the multi view stream.

关键词： Free View Synthesis Multiview Video coding depth coding

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EFFICIENT EDGE-PRESERVING INTERPOLATION AND IN-LOOP FILTERS FOR depth MAP COMPRESSION

EFFICIENT EDGE-PRESERVING INTERPOLATION AND IN-LOOP FILTERS ...

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19th IEEE International Conference on Image Processing (ICIP)

作者： Nguyen, Viet-Anh Min, Dongbo Do, Minh N. Adv Digital Sci Ctr Singapore Singapore Univ Illinois Urbana IL 61801 USA

ISBN: (纸本)9781467325332;9781467325349

Due to abrupt signal changes on object boundaries, a depth video compressed by conventional video coding standards often introduces serious coding artifacts over the boundaries, which severely affect the quality of a synthesized view. In this paper, we propose an edge-preserving depth interpolation filter based on weighted mode filtering to provide more accurate fractional-pixel samples in the motion-compensated interpolation for an effective inter-coding of the depth video. In addition, an efficient post-processing method is also proposed to further suppress the coding artifacts on the depth video and utilized as an in-loop filter. Experimental results show the proposed methods can significantly improve the synthesized view quality in terms of both objective and subjective measures.

关键词： Weighted mode filtering (WMF) depth coding 3D video motion-compensated interpolation

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