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Author

A. Vincent

Bio: A. Vincent is an academic researcher. The author has contributed to research in topics: Temporal resolution & Stereoscopy. The author has an hindex of 2, co-authored 2 publications receiving 280 citations.

Papers
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Journal ArticleDOI
TL;DR: It was found that spatial filtering of one channel of a stereo video-sequence may be an effective means of reducing the transmission bandwidth: the overall sensation of depth was unaffected by low-pass filtering, while ratings of quality and of sharpness were strongly weighted towards the eye with the greater spatial resolution.
Abstract: We explored the response of the human visual system to mixed-resolution stereo video-sequences, in which one eye view was spatially or temporally low-pass filtered. It was expected that the perceived quality, depth, and sharpness would be relatively unaffected by low-pass filtering, compared to the case where both eyes viewed a filtered image. Subjects viewed two 10-second stereo video-sequences, in which the right-eye frames were filtered vertically (V) and horizontally (H) at 1/2 H, 1/2 V, 1/4 H, 1/4 V, 1/2 H 1/2 V, 1/2 H 1/4 V, 1/4 H 1/2 V, and 1/4 H 1/4 V resolution. Temporal filtering was implemented for a subset of these conditions at 1/2 temporal resolution, or with drop-and-repeat frames. Subjects rated the overall quality, sharpness, and overall sensation of depth. It was found that spatial filtering produced acceptable results: the overall sensation of depth was unaffected by low-pass filtering, while ratings of quality and of sharpness were strongly weighted towards the eye with the greater spatial resolution. By comparison, temporal filtering produced unacceptable results: field averaging and drop-and-repeat frame conditions yielded images with poor quality and sharpness, even though perceived depth was relatively unaffected. We conclude that spatial filtering of one channel of a stereo video-sequence may be an effective means of reducing the transmission bandwidth.

217 citations

Proceedings ArticleDOI
10 Sep 2000
TL;DR: It was found that the binocular percept depended on the type of degradation: for low-pass filtering, the Binocular percept was dominated by the high-quality image, whereas for quantization it corresponded to the average of the inputs to the two eyes.
Abstract: The bandwidth required to transmit stereoscopic video images is nominally twice that required for standard, monoscopic images. One method of reducing the required bandwidth is to code the two video streams asymmetrically. We assessed the perceptual impact of this bandwidth-reduction technique for low-pass filtering, DCT-based quantization, and a combination of filtering and quantization. It was found that the binocular percept depended on the type of degradation: for low-pass filtering, the binocular percept was dominated by the high-quality image, whereas for quantization it corresponded to the average of the inputs to the two eyes. The results indicated that asymmetrical coding is a promising technique for reducing storage and transmission bandwidth of stereoscopic sequences.

64 citations


Cited by
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Journal ArticleDOI
31 Jan 2011
TL;DR: An overview of the algorithmic design used for extending H.264/MPEG-4 AVC towards MVC is provided and a summary of the coding performance achieved by MVC for both stereo- and multiview video is provided.
Abstract: Significant improvements in video compression capability have been demonstrated with the introduction of the H.264/MPEG-4 advanced video coding (AVC) standard. Since developing this standard, the Joint Video Team of the ITU-T Video Coding Experts Group (VCEG) and the ISO/IEC Moving Picture Experts Group (MPEG) has also standardized an extension of that technology that is referred to as multiview video coding (MVC). MVC provides a compact representation for multiple views of a video scene, such as multiple synchronized video cameras. Stereo-paired video for 3-D viewing is an important special case of MVC. The standard enables inter-view prediction to improve compression capability, as well as supporting ordinary temporal and spatial prediction. It also supports backward compatibility with existing legacy systems by structuring the MVC bitstream to include a compatible “base view.” Each other view is encoded at the same picture resolution as the base view. In recognition of its high-quality encoding capability and support for backward compatibility, the stereo high profile of the MVC extension was selected by the Blu-Ray Disc Association as the coding format for 3-D video with high-definition resolution. This paper provides an overview of the algorithmic design used for extending H.264/MPEG-4 AVC towards MVC. The basic approach of MVC for enabling inter-view prediction and view scalability in the context of H.264/MPEG-4 AVC is reviewed. Related supplemental enhancement information (SEI) metadata is also described. Various “frame compatible” approaches for support of stereo-view video as an alternative to MVC are also discussed. A summary of the coding performance achieved by MVC for both stereo- and multiview video is also provided. Future directions and challenges related to 3-D video are also briefly discussed.

683 citations

Journal ArticleDOI
26 Jul 2010
TL;DR: The most important perceptual aspects of stereo vision are discussed and their implications for stereoscopic content creation are formalized into a set of basic disparity mapping operators that enable us to control and retarget the depth of a stereoscopic scene in a nonlinear and locally adaptive fashion.
Abstract: This paper addresses the problem of remapping the disparity range of stereoscopic images and video. Such operations are highly important for a variety of issues arising from the production, live broadcast, and consumption of 3D content. Our work is motivated by the observation that the displayed depth and the resulting 3D viewing experience are dictated by a complex combination of perceptual, technological, and artistic constraints. We first discuss the most important perceptual aspects of stereo vision and their implications for stereoscopic content creation. We then formalize these insights into a set of basic disparity mapping operators. These operators enable us to control and retarget the depth of a stereoscopic scene in a nonlinear and locally adaptive fashion. To implement our operators, we propose a new strategy based on stereoscopic warping of the input video streams. From a sparse set of stereo correspondences, our algorithm computes disparity and image-based saliency estimates, and uses them to compute a deformation of the input views so as to meet the target disparities. Our approach represents a practical solution for actual stereo production and display that does not require camera calibration, accurate dense depth maps, occlusion handling, or inpainting. We demonstrate the performance and versatility of our method using examples from live action post-production, 3D display size adaptation, and live broadcast. An additional user study and ground truth comparison further provide evidence for the quality and practical relevance of the presented work.

418 citations

Proceedings ArticleDOI
TL;DR: In this paper, the importance of various causes and aspects of visual discomfort was clarified and the following factors were identified: (1) excessive demand of accommodation-convergence linkage, e.g., by fast motion in depth, viewed at short distances, 3D artefacts resulting from insufficient depth information in the incoming data signal yielding spatial and temporal inconsistencies, and unnatural amounts of blur.
Abstract: Visual discomfort has been the subject of considerable research in relation to stereoscopic and autostereoscopic displays, but remains an ambiguous concept used to denote a variety of subjective symptoms potentially related to different underlying processes. In this paper we clarify the importance of various causes and aspects of visual comfort. Classical causative factors such as excessive binocular parallax and accommodation-convergence conflict appear to be of minor importance when disparity values do not surpass one degree limit of visual angle, which still provides sufficient range to allow for satisfactory depth perception in consumer applications, such as stereoscopic television. Visual discomfort, however, may still occur within this limit and we believe the following factors to be the most pertinent in contributing to this: (1) excessive demand of accommodation-convergence linkage, e.g., by fast motion in depth, viewed at short distances, (2) 3D artefacts resulting from insufficient depth information in the incoming data signal yielding spatial and temporal inconsistencies, and (3) unnatural amounts of blur. In order to adequately characterize and understand visual discomfort, multiple types of measurements, both objective and subjective, are needed.

293 citations

Journal ArticleDOI
01 Apr 2006
TL;DR: Results on asymmetric and symmetric coding showed that the relationship between perceived image quality and average bit rate is not straightforward, and in some cases, image quality ratings of a symmetric coded pair can be higher than for an asymmetriccoded pair, even if the averaged bit rate for the symmetric pair is lower, than for the asymmetric pair.
Abstract: JPEG compression of the left and right components of a stereo image pair is a way to save valuable bandwidth when transmitting stereoscopic images. This paper presents results on the effects of camera-base distance (B) and JPEG coding on overall image quality, perceived depth, perceived sharpness, and perceived eye strain. In the experiment, two stereoscopic still scenes were used, varying in depth (three different camera-base distances: 0, 8, and 12 cm) and compression ratio (4 levels: original, 1:30, 1:40, and 1:60). All levels of compression were applied to both the left and right stereo image, resulting in a 4 × 4 matrix of all possible symmetric and asymmetric coding combinations. The observers were asked to assess image quality, sharpness, depth, and eye strain. Results showed that an increase in JPEG coding had a negative effect on image quality, sharpness, and eye strain, but had no effect on perceived depth. An increase in camera-base distance increased perceived depth and reported eye strain, but had no effect on perceived sharpness. Results on asymmetric and symmetric coding showed that the relationship between perceived image quality and average bit rate is not straightforward. In some cases, image quality ratings of a symmetric coded pair can be higher than for an asymmetric coded pair, even if the averaged bit rate for the symmetric pair is lower, than for the asymmetric pair. Furthermore, sharpness and eye strain correlated highly and medium, respectively, with perceived image quality.

188 citations

Journal ArticleDOI
TL;DR: The correlation between subjective and objective evaluation of color plus depth video and transmission over Internet protocol (IP) is investigated, and subjective results are used to determine more accurate objective quality assessment metrics for 3D color plus Depth video.
Abstract: In the near future, many conventional video applications are likely to be replaced by immersive video to provide a sense of ldquobeing there.rdquo This transition is facilitated by the recent advancement of 3D capture, coding, transmission, and display technologies. Stereoscopic video is the simplest form of 3D video available in the literature. ldquoColor plus depth maprdquo based stereoscopic video has attracted significant attention, as it can reduce storage and bandwidth requirements for the transmission of stereoscopic content over communication channels. However, quality assessment of coded video sequences can currently only be performed reliably using expensive and inconvenient subjective tests. To enable researchers to optimize 3D video systems in a timely fashion, it is essential that reliable objective measures are found. This paper investigates the correlation between subjective and objective evaluation of color plus depth video. The investigation is conducted for different compression ratios, and different video sequences. Transmission over Internet protocol (IP) is also investigated. Subjective tests are performed to determine the image quality and depth perception of a range of differently coded video sequences, with packet loss rates ranging from 0% to 20%. The subjective results are used to determine more accurate objective quality assessment metrics for 3D color plus depth video.

169 citations