Can 3D synthesized views be reliably assessed through usual subjective and objective evaluation protocols?

International audienceThis paper addresses the problem of evaluating virtual view synthesized images in the multi-view video context. As a matter of fact, view synthesis brings new types of distortion. The question refers to the ability of the traditional used objective metrics to assess synthesized views quality, considering the new types of artifacts. The experiments conducted to determine their reliability consist in assessing seven different view synthesis algorithms. Subjective and objective measurements have been performed. Results show that the most commonly used objective metrics can be far from human judgment depending on the artifact to deal with

Perceived quality of DIBR-based synthesized views

International audienceThis paper considers the reliability of usual assessment methods when evaluating virtual synthesized views in the multi-view video context. Virtual views are generated from Depth Image Based Rendering (DIBR) algorithms. Because DIBR algorithms involve geometric transformations, new types of artifacts come up. The question regards the ability of commonly used methods to deal with such artifacts. This paper investigates how correlated usual metrics are to human judgment. The experiments consist in assessing seven different view synthesis algorithms by subjective and objective methods. Three different 3D video sequences are used in the tests. Resulting virtual synthesized sequences are assessed through objective metrics and subjective protocols. Results show that usual objective metrics can fail assessing synthesized views, in the sense of human judgment

Navigation domain representation for interactive multiview imaging

Enabling users to interactively navigate through different viewpoints of a static scene is a new interesting functionality in 3D streaming systems. While it opens exciting perspectives towards rich multimedia applications, it requires the design of novel representations and coding techniques in order to solve the new challenges imposed by interactive navigation. Interactivity clearly brings new design constraints: the encoder is unaware of the exact decoding process, while the decoder has to reconstruct information from incomplete subsets of data since the server can generally not transmit images for all possible viewpoints due to resource constrains. In this paper, we propose a novel multiview data representation that permits to satisfy bandwidth and storage constraints in an interactive multiview streaming system. In particular, we partition the multiview navigation domain into segments, each of which is described by a reference image and some auxiliary information. The auxiliary information enables the client to recreate any viewpoint in the navigation segment via view synthesis. The decoder is then able to navigate freely in the segment without further data request to the server; it requests additional data only when it moves to a different segment. We discuss the benefits of this novel representation in interactive navigation systems and further propose a method to optimize the partitioning of the navigation domain into independent segments, under bandwidth and storage constraints. Experimental results confirm the potential of the proposed representation; namely, our system leads to similar compression performance as classical inter-view coding, while it provides the high level of flexibility that is required for interactive streaming. Hence, our new framework represents a promising solution for 3D data representation in novel interactive multimedia services

View and depth preprocessing for view synthesis enhancement

In the paper, two preprocessing methods for virtual view synthesis are presented. In the first approach, both horizontal and vertical resolutions of the real views and the corresponding depth maps are doubled in order to perform view synthesis on images with densely arranged points. In the second method, real views are filtered in order to eliminate blurred or improperly shifted edges of the objects. Both methods are performed prior to synthesis, thus they may be applied to different Depth-Image-Based Rendering algorithms. In the paper, for both proposed methods, the achieved quality gains are presented

Objective View Synthesis Quality Assessment

International audienceView synthesis brings geometric distortions which are not handled efficiently by existing image quality assessment metrics. Despite the widespread of 3-D technology and notably 3D television (3DTV) and free-viewpoints television (FTV), the field of view synthesis quality assessment has not yet been widely investigated and new quality metrics are required. In this study, we propose a new full-reference objective quality assessment metric: the View Synthesis Quality Assessment (VSQA) metric. Our method is dedicated to artifacts detection in synthesized view-points and aims to handle areas where disparity estimation may fail: thin objects, object borders, transparency, variations of illumination or color differences between left and right views, periodic objects... The key feature of the proposed method is the use of three visibility maps which characterize complexity in terms of textures, diversity of gradient orientations and presence of high contrast. Moreover, the VSQA metric can be defined as an extension of any existing 2D image quality assessment metric. Experimental tests have shown the effectiveness of the proposed method