In 3-D video, view synthesis with depth-image-based rendering is employed to generate any virtual view between available camera views. Distortions in depthmap induce geometry changes in the virtual views, and thus de...
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In 3-D video, view synthesis with depth-image-based rendering is employed to generate any virtual view between available camera views. Distortions in depthmap induce geometry changes in the virtual views, and thus degrade the performance of view synthesis. This paper proposes a depth map coding method to improve the performance of view synthesis based on distortion analyses. The major technical innovation of this paper is to formulate maximum tolerable depth distortion (MTDD) and depth disocclusion mask (DDM), since such depth sensitivity for view synthesis and inter-view redundancy can be well utilized in coding. To be more specific, we define two different encoders (e.g., base encoder and side encoder) for depthmaps in left and right views, respectively. For base encoding, different types of coding units are extracted based on the distribution of MTDD and assigned with different quantitative parameters for coding. For side encoding, a warped-SKIP mode is designed to remove inter-view redundancy based on the distribution of DDM. The experimental results show that the proposed scheme not only achieves high view synthesis performance, but also reduce the computational complexity of encoding.
In texture-plus-depth format, depthmap compression is an important task. Different from normal texture images, depthmaps have less texture information, while contain many homogeneous regions separated by sharp edges...
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In texture-plus-depth format, depthmap compression is an important task. Different from normal texture images, depthmaps have less texture information, while contain many homogeneous regions separated by sharp edges. This feature will be employed to form an efficient depth map coding scheme in this paper. Firstly, the histogram of the depthmap will be analyzed to find an appropriate threshold that segments the depthmap into the foreground and background regions, allowing the edge between these two kinds of regions to be obtained. Secondly, the two regions will be encoded through rate distortion optimization with a shape adaptive wavelet transform, while the edges are lossless encoded with JBIG2. Finally, a depth-updating algorithm based on the threshold and the depth range is applied to enhance the quality of the decoded depthmaps. Experimental results demonstrate the effective performance on both the depthmap quality and the synthesized view quality.
New data formats that include both video and the corresponding depthmaps, such as multiview plus depth (MVD), enable new video applications in which intermediate video views (virtual views) can be generated using the...
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ISBN:
(纸本)9780819479365
New data formats that include both video and the corresponding depthmaps, such as multiview plus depth (MVD), enable new video applications in which intermediate video views (virtual views) can be generated using the transmitted/stored video views (reference views) and the corresponding depthmaps as inputs. We propose a depth map coding method based on a new distortion measurement by deriving relationships between distortions in coded depthmap and rendered view. In our experiments we use a codec based on H.264/AVC tools, where the rate-distortion (RD) optimization for depth encoding makes use of the new distortion metric. Our experimental results show the efficiency of the proposed method, with coding gains of up to 1.6 dB in interpolated frame quality as compared to encoding the depthmaps using the same coding tools but applying RD optimization based on conventional distortion metrics.
A complete encoding solution for efficient intra-based depthmap compression is proposed in this paper. The algorithm, denominated predictive depthcoding (PDC), was specifically developed to efficiently represent the...
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A complete encoding solution for efficient intra-based depthmap compression is proposed in this paper. The algorithm, denominated predictive depthcoding (PDC), was specifically developed to efficiently represent the characteristics of depthmaps, mostly composed by smooth areas delimited by sharp edges. At its core, PDC involves a directional intra prediction framework and a straightforward residue coding method, combined with an optimized flexible block partitioning scheme. In order to improve the algorithm in the presence of depth edges that cannot be efficiently predicted by the directional modes, a constrained depth modeling mode, based on explicit edge representation, was developed. For residue coding, a simple and low complexity approach was investigated, using constant and linear residue modeling, depending on the prediction mode. The performance of the proposed intra depth map coding approach was evaluated based on the quality of the synthesized views using the encoded depthmaps and original texture views. The experimental tests based on all intra configuration demonstrated the superior rate-distortion performance of PDC, with average bitrate savings of 6%, when compared with the current state-of-the-art intra depth map coding solution present in the 3D extension of a high-efficiency video coding (3D-HEVC) standard. By using view synthesis optimization in both PDC and 3D-HEVC encoders, the average bitrate savings increase to 14.3%. This suggests that the proposed method, without using transform-based residue coding, is an efficient alternative to the current 3D-HEVC algorithm for intra depth map coding.
The 3D extension of High Efficiency Video coding significantly improves the coding efficiency of 3D video at the expense of computational complexity. This paper presents a novel fast mode decision algorithm for depth ...
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The 3D extension of High Efficiency Video coding significantly improves the coding efficiency of 3D video at the expense of computational complexity. This paper presents a novel fast mode decision algorithm for depth map coding based on the grayscale similarity and inter-view correlation. First, depthmap grayscale similarity is adopted to judge whether the reference frame could assist the coding of the current frame. When the difference in the average grayscale between the co-located coding unit (CU) and the current CU is smaller than the similarity threshold, the depth level of the current CU will be restricted by that of the coded reference CU. Second, the grayscale similarity and inter-view correlation are jointly used for dependent views to achieve early decision on the best prediction unit (PU) mode. The mode decision procedure will be determined early when the co-located CU, which has a grayscale similarity with the current CU, selects Merge or Inter 2Nx2N as the best prediction mode. Moreover, when the corresponding CU in the independent view selects Merge or Inter 2N x 2N as the best prediction mode, the current CU will skip other PU modes checking based on the strong inter-view correlation. Finally, different strategies are proposed for the P-frames and B-frames of dependent views in view of the characteristics of different prediction structures. For B frames, the PU mode information of the coded independent view is utilized as reference to skip the unnecessary mode decision processes. For P frames, the spatial-temporal correlation is considered in the process of early mode decision to determine whether to choose the Merge mode or Inter 2N x 2N as the best mode. Experimental results show that our proposed scheme achieves considerable time saving with negligible degradation of coding performance.
In stereoscopic video coding, vast and varied coding modes are utilized to adapt various video content. In order to select the optimal coding parameter set for coding unit, rate-distortion optimization (RDO) criterion...
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In stereoscopic video coding, vast and varied coding modes are utilized to adapt various video content. In order to select the optimal coding parameter set for coding unit, rate-distortion optimization (RDO) criterion is employed as a critical technology. It has been found that the Lagrangian Multiplier of RDO criterion for depth map coding has an impact on coding performance of stereoscopic video. Therefore, the Lagrangian Multiplier should be determined properly. In this paper, we first provide an analysis of the factors that could affect the Lagrangian Multiplier. Then, an adaptive Lagrangian Multiplier derivation model for depth map coding in 3D-HEVC is established by involving these affect factors. At last, the optimal coding parameter set can be obtained by the adjusted RDO criterion through the derived Lagrangian Multiplier. Experimental results demonstrate that the proposed adaptive Lagrangian Multiplier derivation model can lead to a favorable coding performance of stereoscopic video. An average 3.13% bitrate saving can be achieved compared with the HTM 16.0 reference software. Moreover, compared to two other state-of-art methods, namely the Yang's method and the Huo's method, the proposed model can achieve 0.21% and 0.11% bitrate savings, respectively.
In depth map coding, rate-distortion optimization for those pixels that will cause occlusion in view synthesis is a rather challenging task, since the synthesis distortion estimation is complicated by the warping comp...
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In depth map coding, rate-distortion optimization for those pixels that will cause occlusion in view synthesis is a rather challenging task, since the synthesis distortion estimation is complicated by the warping competition and the occlusion order can be easily changed by the adopted optimization strategy. In this paper, an efficient depth map coding approach using allowable depthmap distortions is proposed for occlusion-inducing pixels. First, we derive the range of allowable depth level change for both the zero disparity error case and non-zero disparity error case with theoretic and geometrical proofs. Then, we formulate the problem of optimally selecting the depth distortion within allowable depth distortion range with the objective to minimize the overall synthesis distortion involved in the occlusion. The unicity and occlusion order invariance properties of allowable depth distortion range is demonstrated. Finally, we propose a dynamic programming based algorithm to locate the optimal depth distortion for each pixel. Simulation results illustrate the performance improvement of the proposed algorithm over the other state-of-the-art depth map coding optimization schemes.
depth map coding aims to maximize the perceived visual quality of the synthesized virtual views instead of the depthmaps. Therefore, it is necessary to develop new synthesized view distortion model to capture the eff...
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depth map coding aims to maximize the perceived visual quality of the synthesized virtual views instead of the depthmaps. Therefore, it is necessary to develop new synthesized view distortion model to capture the effect of depthmap distortion on the final quality of the synthesized views. This paper proposes a structural similarity-based synthesized view distortion (SS-SVD) model to relate perceptual distortion in coded depthmap and synthesized view by deriving the relationship between the depthmap distortion, warping error and synthesized view distortion. The SS-SVD model is applied to the rate distortion optimization which describes the relationship between depthcoding bit-rate and synthesized view distortion for depth map coding mode selection. Experimental results show that the proposed SS-SVD method obtains both better rate distortion performance and perceptual quality of synthesized views than JM reference software(1).
Rate-distortion optimisation (RDO) is the key technology that is used to choose the optimal coding parameters in video coding. As the Lagrangian multiplier plays a vital role in RDO, a model-based Lagrangian multiplie...
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Rate-distortion optimisation (RDO) is the key technology that is used to choose the optimal coding parameters in video coding. As the Lagrangian multiplier plays a vital role in RDO, a model-based Lagrangian multiplier derivation method is proposed for depth map coding. This method is based on the analysis of the relationships among the Lagrangian multiplier, the coding distortion, the coding bitrate and the quantisation step. Experimental results demonstrate that the proposed method can achieve an average 3.42% bitrate saving compared with the method in HTM 16.0 reference software, and an average 0.41% bitrate saving compared with a state-of-art method.
3D-high efficiency video coding (3D-HEVC) contains more encoding viewpoints than traditional HEVC, resulting in a significant increase of coding complexity. In this paper, we propose a low complexity intra mode decisi...
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3D-high efficiency video coding (3D-HEVC) contains more encoding viewpoints than traditional HEVC, resulting in a significant increase of coding complexity. In this paper, we propose a low complexity intra mode decision algorithm to reduce the number of intra modes by detecting the flat area and texture direction of the depthmap. The corresponding intra prediction modes are skipped when the flat region condition is satisfied. Otherwise, the direction of the edge is detected to decrease the number of angle modes in rough mode decision, which can reduce the intra-coding complexity and coding time cost. Experimental results demonstrate that the proposed algorithm achieves on average 36.48% time saving with negligible degradation of coding performance.
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