共查询到20条相似文献,搜索用时 15 毫秒
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《Signal Processing: Image Communication》2006,21(2):130-142
Video transmission over error-prone networks can suffer from packet erasures which can greatly reduce the quality of the received video. Error concealment methods reduce the perceived quality degradation at the receiving end by masking the effects of such errors. They accomplish this by exploiting temporal and spatial correlations that exist in image sequences. Spatial error concealment approaches conceal errors by making use of spatial information only which is necessary in cases where motion information is not available or reliable. The performance of such methods can be greatly increased if perceptual considerations are taken into account as, e.g., the preservation of edge information. This paper proposes a spatial error concealment method that uses edge-related information in order not only to preserve existing edges but also to avoid introducing new strong ones by switching to a smooth approximation of missing information where necessary. A novel switching algorithm which uses the directional entropy of neighbouring edges chooses between two interpolation methods, a directional along detected edges or a bilinear using the nearest neighbouring pixels. Results show that the performance of the proposed method is better compared to both ‘single interpolation’ and to edge strength-based switching methods. 相似文献
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Ji Wenping Shen Lansun 《电子科学学刊(英文版)》2007,24(3):417-420
This letter presents a novel spatial error concealment algorithm for the H.264 video coding. The error concealment algorithm is based on directional interpolation. Mojette transform is used to estimate the orientation features of the damaged blocks,and the image is interpolated in the appro-priate directions. The proposed method is compared with bilinear interpolation algorithm in the ref-erence implementation of H.264 and all directional interpolation. Experimental results prove that the proposed algorithm has better subjective and objective image reconstruction quality. 相似文献
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在易发生错误的卫星信道的传输过程中,视频会产生误码和丢包.根据视频的边缘特征,将丢失块分成平坦块、边缘块和纹理块.然后,自适应地选择双线性内插、方向内插或者新方向加权内插作为内插方法,提高重构视频质量,加速误码掩盖过程.为了减少梯度计算量,将噪声像素从候选预测像素列表中剔除.为了准确地呈现图像的方向信息以及抑制噪声,选择Prewitt算子作为梯度滤波器.另外,使用分数像素内插来提高插值精度,适应高清视频应用.客观评价结果显示,在解码时间稍微增加的情况下,峰值信噪比大约提升了3 dB.主观比较结果显示,提出的算法能够获得更高的视觉质量. 相似文献
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Selective recovery of video packet loss using error concealment 总被引:3,自引:0,他引:3
An efficient recovery method using error concealment is proposed for video packet loss in fast packet switching networks. In this method, the receiver detects the damaged picture area caused by packet loss from the structured picture data received, makes error concealments, notifies the transmitter, and continues decoding. The transmitter, having received the notice, calculates the affected picture area in the local decoded picture and continues encoding without using this affected area. In this selective recovery method, video signals are not stopped even if a long propagation delay exists, no additional information is transmitted to error recovery and conventional coding algorithms can be used. The proposed method is suitable for multipoint communication. Simulation results show the affected picture area is localized for a considerable time attesting to the method's effectiveness 相似文献
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In this paper, an original spatial shape error-concealment technique, to be used in the context of object-based image and video coding schemes, is proposed. In this technique, it is assumed that the shape of the corrupted object at hand is in the form of a binary alpha plane, in which some of the shape data is missing due to channel errors. From this alpha plane, a contour corresponding to the border of the object can be extracted. However, due to errors, some parts of the contour will be missing and, therefore, the contour will be broken. The proposed technique relies on the interpolation of the missing contours with Bézier curves, which is done based on the available surrounding contours. After all the missing parts of the contour have been interpolated, the concealed alpha plane can be easily reconstructed from the fully recovered contour and used instead of the erroneous one improving the final subjective impact. 相似文献
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提出了一种改进的H.264自适应帧内错误隐藏算法,使重建图像具有较好的平滑性,同时有效恢复了边缘信息。通过区域选择、亮度信号插值、块位置检测等方式,有效降低了解码运算量并解决了工程应用中的难点。在MATLAB和H.264标准测试平台JM86上分别进行验证,结果表明,该算法简单实用,适于实时处理,峰值信噪比高出一般传统方法 3 dB,改善了重建图像的主、客观质量,具有较高的应用价值. 相似文献
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Conventional error concealment (EC) algorithms suffer from the quality degradation as the frame number increases within a group of pictures (GOP). Presented is an EC framework to improve the quality of frames in the rear of a GOP. The framework is composed of two phases: forward decoding and backward frame update. Experimental results show better performance in peak signal-to-noise ratio and subjective quality is obtained using this EC framework. 相似文献
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Packet video error concealment with Gaussian mixture models. 总被引:1,自引:0,他引:1
Daniel Persson Thomas Eriksson Per Hedelin 《IEEE transactions on image processing》2008,17(2):145-154
In this paper, Gaussian mixture modeling is applied to error concealment for block-based packet video. A Gaussian mixture model for video data is obtained offline and is thereafter utilized online in order to restore lost blocks from spatial and temporal surrounding information. We propose estimators on closed form for missing data in the case of varying available neighboring contexts. Our error concealment strategy increases peak signal-to-noise ratio compared to previously proposed schemes. Examples of improved subjective visual quality by means of the proposed method are also supplied. 相似文献
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Resynchronizing variable-length codes (RVLCs) for large alphabets are designed by first creating resynchronizing Huffman codes and then adding an extended synchronizing codeword, and the RVLCs are applied to both JPEG and wavelet-based image compression. The RVLCs demonstrate the desired resynchronization properties, both at a symbol level and structurally so that decoded data can be correctly placed within an image following errors. The encoded images, when subject to both structural and statistical error detection and concealment, can tolerate BERs of up to 10-4 and are very tolerant of burst errors. The RVLC-JPEG images have negligible overhead at visually lossless bit rates, while the RVLC-wavelet overhead can be adjusted based on the desired tolerance to burst errors and typically ranges from 7 to 18%. The tolerance to both bit and burst errors demonstrates that images coded with such RVLCs can be transmitted over imperfect channels suffering bit errors or packet losses without channel coding for the image data, or with less channel coding than would be required if the encoded image data could tolerate no bit errors. While the overhead is nontrivial for the RVLC-wavelet images and the lower-rate RVLC-JPEG images, the encoded bitstreams do not have the firm restrictions on numbers or spacings of bit errors that some error correcting codes have, and hence provide more graceful degradation 相似文献
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The adaptive finite-element method (FEM) is an iterative variant of the FEM where, in a first step, an initial mesh with few and low-order elements is generated, the corresponding algebraic problem is solved and the error in the solution is estimated in order to add degrees of freedom in those regions of the domain with the biggest error estimation. This process is repeated until an ending condition is reached. The two basic stages in this method are the error indication and the mesh enrichment. In this paper, within the analysis of waveguiding structures, a new error indicator based on the curl recovery is described. In addition, an overview on refinement techniques is presented, and the h-refinement employed in this study is briefly described. Results obtained with the curl-recovery indicator are discussed and compared with the classical nonadaptive FEM and two previously developed error indicators: the residual and flux continuity indicators. 相似文献
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Spatiotemporal error concealment with optimized mode selection and application to H.264 总被引:2,自引:0,他引:2
S. Belfiore M. Grangetto E. Magli G. Olmo 《Signal Processing: Image Communication》2003,18(10):907-923
In this paper we propose an error concealment algorithm for video transmission over lossy packet networks. The proposed technique is based on temporal and spatial interpolation. A sophisticated mode selection algorithm decides whether to employ the temporal or the spatial part, or a combination thereof, to estimate a missing macroblock; the selection does not rely on knowledge of the original coding modes. The resulting error concealment algorithm is designed so as to optimize both PSNR and visual quality of the restored video sequence, and employs directional interpolation and texture analysis/synthesis. The technique has been applied to H.264 coded video, providing satisfactory results on a number of test sequences. 相似文献
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Chih-Ming Fu Wen-Liang Hwang Chung-Lin Huang 《IEEE transactions on image processing》2007,16(4):1022-1035
We propose a new framework for multiple scalable bitstream video communications over lossy channels. The major feature of the framework is that the encoder estimates the effects of postprocessing concealment and includes those effects in the rate-distortion analysis. Based on the framework, we develop a rate-distortion optimization algorithm to generate multiple scalable bitstreams. The algorithm maximizes the expected peak signal-to-noise ratio by optimally assigning forward error control codes and transmission schemes in a constrained bandwidth. The framework is a general approach motivated by previous methods that perform concealment in the decoder, as in our special case. Simulations show that the proposed approach can be implemented efficiently and that it outperforms previous methods by more than 2 dB. 相似文献
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基于H.263视频解码的错误检测和掩盖 总被引:10,自引:1,他引:10
本文提出了一种应用于H.263视频编码传输的纠错方法,即基于H.263视频解码的错误检测和掩盖算法。这种算法可应用于公共交换电话网(PSTN),Internet或移动信道的视频通信。模拟结果表明,这种纠错方法在不降低编码效率的前提下,使在有噪声干扰的信道上传输图像的质量有显著的改善。 相似文献