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Сжатие видео - Stereoscopic


Английские материалы
Авторы Название статьи Описание Рейтинг
Woontack Woo and Antonio Ortega Overlapped Block Disparity Compensation with Adaptive Windows for Stereo Image Coding
Abstract—In this letter, we propose a modified overlapped block-matching (OBM) scheme for stereo image coding. OBM has been used in video coding but, to the best of our knowledge, it has not been applied to stereo image coding to date. In video coding, OBM has proven useful in reducing blocking artifacts (since multiple vectors can be used for each block), while also maintaining most of the advantages of fixed-size block matching. There are two main novelties in this work. First, we show that OBM techniques can be successfully applied to stereo image coding. Second, we take advantage of the smoothness properties typically found in disparity fields to further improve the performance of OBM in this particular application. Specifically, we note that practical OBM approaches use noniterative estimation techniques, which produce lower quality estimates than iterative methods. By introducing smoothness constraints into the noniterative DV computation, we improve the quality of the estimated disparity as compared to standard noniterative OBM approaches. In addition, we propose a disparity estimation/compensation approach using adaptive windows with variable shapes, which results in a reduction in complexity. We provide experimental results that show that our proposed hybrid OBM scheme achieves a PSNR gain (about 1.5–2 dB) as compared to a simple block-based scheme, with some slight PSNR gains (about 0.2–0.5 dB) in a reduced complexity, as compared to an approach based on standard OBM with half-pixel accuracy.
RAR  210 кбайт
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Kuei-Ann Wen, An-Yi Chen, Yin-Jin Lan, Jun-Lin Lin, and Chia-Huang Lin Three-Dimensional PAC Video Codec for Wireless Data Transmission
Abstract—A newly derived algorithm called three-dimensional polynomial approximation coding (3DPAC) is being utilized in the applications of wireless video transmission. After combining the spatial and temporal domain, the video data is organized in a cube form, which has the features of processing parallelism and great compression ratio. Such a very low bit-rate video codec is able to support the wireless data transmission with a bit rate lower than 9.6 kbits/s. The system architecture will be presented and an experimental demonstration is also shown. For a video sequence of 176 144 frame size, PSNR up to 35 dB maybe obtained under 6.5 kbits/s transmission rate.
RAR  667 кбайт
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W. A. IJsselsteijn, H. de Ridder, and J. Vliegen Subjective Evaluation of Stereoscopic Images: Effects of Camera Parameters and Display Duration
Abstract—In this paper, two experiments are presented that were aimed to investigate the effects of stereoscopic filming parameters and display duration on observers' judgements of naturalness and quality of stereoscopic images. The paper first presents a literature review of temporal factors in stereoscopic vision, with reference to stereoscopic displays. Several studies have indicated an effect of display duration on performance-oriented (criterion based) measures. The experiments reported here were performed to extend the study of display duration from performance to appreciation- oriented measures. In addition, the present study aimed to investigate the effects of manipulating camera separation, convergence distance, and focal length on perceived quality and naturalness.
RAR  140 кбайт
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George A. Triantafyllidis, Dimitrios Tzovaras, and Michael Gerassimos Strintzis, Occlusion and Visible Background and Foreground Areas in Stereo: A Bayesian Approach
Abstract—Efficient techniques are introduced in this paper for the identification of the occlusion and visible background and foreground areas in a noisy stereoscopic image pair. Three different Bayes decision methods are tested for this purpose. The first, and simplest, uses three hypotheses for the formulation of the Bayes decision rules, adopting the right image as a reference. After performing a dual-Bayes decision test having each time as a different image of the stereo pair as reference, consistency checking is added to these tests to form the second method. Finally, four compound hypotheses are used in the third method, which is the most accurate but also the more detailed and computationally involved of the three. Experimental results illustrating the performance of the proposed techniques are presented and evaluated.
RAR  346 кбайт
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Mel Siegel and Shojiro Nagata Just Enough Reality: Comfortable 3-D Viewing via Microstereopsis
Abstract—We address human factors and technology issues for the design of stereoscopic display systems that are natural and comfortable to view. Our title “just enough reality” hints at the contrast between the popularly perceived requirements for strict “virtual reality” and the expert’s pragmatic acceptance of “sufficient reality” to satisfy the human interface requirements of real-world applications. We first review how numerous perceptions and illusions of depth can be exploited to synergistically complement binocular stereopsis. Then we report the results of our experimental studies of stereoscopy with very small interocular separations and correspondingly small on-screen disparities, which we call “microstereopsis.” We outline the implications of microstereopsis for the design of future stereoscopic camera and display systems, especially the possibility of achieving zoneless autostereoscopic displays. We describe a possible class of implementations based on a nonlambertian filter element, and a particular implementation that would use an electronically switched louver filter to realize it.
RAR  463 кбайт
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Detlef Runde How to Realize a Natural Image Reproduction using Stereoscopic Displays with Motion Parallax
Abstract—In order to achieve a realistic image representation with a high degree of telepresence, stereoscopy is known as a very powerful means. Motion parallax is another important visual cue. It contributes to the naturalness of vision and can reduce artifacts of common stereoscopic representation techniques. This paper focuses on the ratio of (real or virtual) camera movement to head movement (“gain of motion parallax”) and on the image reproduction conditions that allow of perceiving a stable and natural stereoscopic image providing motion parallax. Results show that the gain of motion parallax should be adjustable by the viewer. For most observers, the preferred gain is lower than the geometrically correct value of 1. A good starting point seams to be a value of 0.75. All three dimensions of head movement and the individual (and currently actual) interocular distance should be taken into account when calculating the appropriate views. Spatial quantization of eye position should be better than 5 min of arc, and temporal sampling of eye position should be done with 40 Hz or more.
RAR  934 кбайт
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Nikolaos D. Doulamis, Anastasios D. Doulamis, Yannis S. Avrithis, Klimis S. Ntalianis, and Stefanos D. Kollias Efficient Summarization of Stereoscopic Video Sequences
Abstract—An efficient technique for summarization of stereoscopic video sequences is presented in this paper, which extracts a small but meaningful set of video frames using a content-based sampling algorithm. The proposed video-content representation provides the capability of browsing digital stereoscopic video sequences and performing more efficient content-based queries and indexing. Each stereoscopic video sequence is first partitioned into shots by applying a shot-cut detection algorithm so that frames (or stereo pairs) of similar visual characteristics are gathered together. Each shot is then analyzed using stereo-imaging techniques, and the disparity field, occluded areas, and depth map are estimated. A multiresolution implementation of the Recursive Shortest Spanning Tree (RSST) algorithm is applied for color and depth segmentation, while fusion of color and depth segments is employed for reliable video object extraction. In particular, color segments are projected onto depth segments so that video objects on the same depth plane are retained, while at the same time accurate object boundaries are extracted. Feature vectors are then constructed using multidimensional fuzzy classification of segment features including size, location, color, and depth. Shot selection is accomplished by clustering similar shots based on the generalized Lloyd–Max algorithm, while for a given shot, key frames are extracted using an optimization method for locating frames of minimally correlated feature vectors. For efficient implementation of the latter method, a genetic algorithm is used. Experimental results are presented, which indicate the reliable performance of the proposed scheme on real-life stereoscopic video sequences.
RAR  2860 кбайт
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Yoshihiro Kajiki, Hiroshi Yoshikawa, and Toshio Honda Autostereoscopic 3-D Video Display Using Multiple Light Beams with Scanning
Abstract—An autostereoscopic 3-D displaying technique that uses fan-likely placed multiple light beams in a light array with 2-D raster scanning is proposed. This technique is capable of displaying multiple perspective views at high resolution because the number of views only depends on the number of light beams, while the number of light beams does not depend on the resolution of each view. Moreover, dozens or hundreds of perspective views at an angular interval narrower than one degree can be produced if small light sources are used. On the basis of this technique, an experimental 3-D display system capable of producing 45-view video images at an angular interval of 0.5 degrees at a time is developed. Furthermore, the effectiveness of the technique is demonstrated by using this system.
RAR  168 кбайт
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Klaus Hopf An Autostereoscopic Display Providing Comfortable Viewing Conditions and a High Degree of Telepresence
Abstract—Research and development on 3-D displays make great progress and even autostereoscopic 3-D displays are on the verge of being put onto the market. The main market within the near future will be, besides entertainment applications, the field of multimedia desktop displays. The use of autostereoscopic displays makes it possible to watch 3-D images without special glasses. Particularly in communication applications dark spectacles hamper natural face-to-face communication. This paper presents a concept for a realization of a 3-D desktop display which was developed at the Heinrich–Hertz-Institute. In this concept a collimation optic was combined with an autostereoscopic display unit. In the past, collimation optics were usually used in head mounted devices. Only a few realizations of autostereoscopic displays are known, which combine autostereoscopic technologies with collimation optics [5]. Studies performed at NASA’s Langley Research Center showed that the usable volume of depth can extend to large values when a collimation optic is integrated in a stereoscopic display [9]. Results of our work showed that a “puppet theater effect” is not perceptible when a collimated display is used. Two autostereoscopic prototype setups suitable for communication applications were realized that avoid the disadvantages of most common stereoscopic displays.
RAR  150 кбайт
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Hirokazu Yamanoue, Makoto Okui, and Ichiro Yuyama A Study on the Relationship Between Shooting Conditions and Cardboard Effect of Stereoscopic Images
Abstract—In this paper, we examine the cardboard effect by varying such image acquisition parameters as lighting intercamera distances, lens focal length, and presence or absence of motion parallax and backgrounds in program production. Subjective evaluation tests show that binocular disparity calculated from cameraseparation lens selection and convergence point are dominant factors. The cardboard effect can be effectively avoided or lessened by enhancing increasing the binocular parallax. In case of actual program production, it is practical to use standard lenses or ones close in focal length to standard lenses, and to set camera separation around the same as the average eye separation of human eyes in order to mitigate the cardboard effect. When binocular disparity is small using lenses with long focal length, other cues, such as motion parallax accompanied by the relative movement between subjects and cameras, are effective.
RAR  168 кбайт
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Makoto Okui, Atsuo Hanazato, Fumio Okano, and Ichiro Yuyama A Study on Scanning Methods for a Field-Sequential Stereoscopic Display
Abstract—This paper focuses on the scanning methods of a fieldsequential stereoscopic display system. We examined the advantages and disadvantages of several scanning methods to identify the most suitable one for the field-sequential stereoscopic display technique. An evaluation test using a system with 525 scanning lines and a 120-Hz field frequency was conducted. The results show that the picture quality of the 4:2 or 4:1 interlace method, which maintains high vertical resolution, is superior to that of the simple 2:1 interlace one. We also developed an experimental field-sequential stereoscopic system for HDTV with 4:2 interlacing and confirmed that it is possible to display high-quality stereoscopic HDTV pictures in full 1125-line vertical resolutions.
RAR  465 кбайт
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Reinhard Bцrner, Bernd Duckstein, Oliver Machui, Hans Rцder, Thomas Sinnig, and Thomas Sikora, A Family of Single-User Autostereoscopic Displays with Head-Tracking Capabilities
Abstract—In this paper, we present prototypes of autostereoscopic displays which allow single users to experience stereoscopic vision without the need for special eye glasses or helmet-mounted displays. The design of the displays is based on lenticular raster plates and includes a number of novel concepts for tracking of raster plates or projection lenses to account for changes of the viewers position in front of the screen. Applications envisioned include 3-D multimedia desktop visualization for medical and biological imaging, design, and architecture, as well as computer games and 3-D virtual reality in general. Concepts and results for both high-resolution flat liquid-crystal panel monitors for PC desktop applications as well as large screen high resolution displays using rear-projection technology are discussed.
RAR  714 кбайт
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Franёcoys Labontґe, Chon Tam Le Dinh, Jocelyn Faubert, and Paul Cohen Spatiotemporal Spectral Coding of Stereo Image Sequences
Abstract—This paper presents a new compression scheme for interlaced stereoscopic sequences which differentiates between a region of fixation and a peripheral area, and thereby compacts the stereoscopic information into the spectral space of a monocular video channel. Spectral compression is achieved by avoiding transmitting high-frequency information over the entire images, but only within and around the region where the observer acuity is the highest. The proposed approach consists of decomposing the left and right fields of the stereoscopic pairs into low-pass and high-pass components. High-frequency components are then limited to a fixation region, thus allowing a reduction of their spectral extent. A composite video signal is then formed by positioning the different components into the available spectral space through filtering and modulation. The approach is compatible with the NTSC standard in the sense that the same color subcarrier and the same spectral region are used for the chrominance components. Strategies are proposed for the estimation of the fixation region, based upon a psychophysical study on visual strategies during depth discrimination tasks.
RAR  561 кбайт
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