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结构相似度索引耦合最优稀疏表示的大规模损坏图像动态修复 被引量:11
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作者 耿卫江 《科学技术与工程》 北大核心 2014年第25期107-114,共8页
当前的图像修复算法在处理小面积损坏图像时,可取得较佳的视觉质量;但难以用于高对比度边缘和高频分量的大面积损坏图像的修复,存在明显的模糊效应与块效应,使得修复质量较差。对此,提出了结构相似度索引耦合优化稀疏表示的大规模损坏... 当前的图像修复算法在处理小面积损坏图像时,可取得较佳的视觉质量;但难以用于高对比度边缘和高频分量的大面积损坏图像的修复,存在明显的模糊效应与块效应,使得修复质量较差。对此,提出了结构相似度索引耦合优化稀疏表示的大规模损坏图像动态修复机制。基于数据度与置信度构造图像块先验模型,提取损坏图像的已知块;再引入K-SVD算法和拉格朗日乘数机制,构造最优字典矩阵,优化稀疏表示,以重构目标图像损坏区域;并设计结构相似度索引与动态更新机制,估算稀疏表示系数,并动态更新字典矩阵,输出修复图像。最后测试了其机制性能。结果表明:与当前图像修复算法相比,在大规模损坏图像与高对比度边缘图像修复中,具有更好的修复效果、更高的相似度,显著消除了模糊效应与块效应。 展开更多
关键词 结构相似度索引 优化稀疏表示 最优字典矩阵 块先验 图像动态修复
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Privacy-Preserving Top-k Keyword Similarity Search over Outsourced Cloud Data 被引量:1
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作者 TENG Yiping CHENG Xiang +2 位作者 SU Sen WANG Yulong SHUANG Kai 《China Communications》 SCIE CSCD 2015年第12期109-121,共13页
In this paper,we study the problem of privacy-preserving top-k keyword similarity search over outsourced cloud data.Taking edit distance as a measure of similarity,we first build up the similarity keyword sets for all... In this paper,we study the problem of privacy-preserving top-k keyword similarity search over outsourced cloud data.Taking edit distance as a measure of similarity,we first build up the similarity keyword sets for all the keywords in the data collection.We then calculate the relevance scores of the elements in the similarity keyword sets by the widely used tf-idf theory.Leveraging both the similarity keyword sets and the relevance scores,we present a new secure and efficient treebased index structure for privacy-preserving top-k keyword similarity search.To prevent potential statistical attacks,we also introduce a two-server model to separate the association between the index structure and the data collection in cloud servers.Thorough analysis is given on the validity of search functionality and formal security proofs are presented for the privacy guarantee of our solution.Experimental results on real-world data sets further demonstrate the availability and efficiency of our solution. 展开更多
关键词 similarity keyword preserving cloud collection privacy validity files ranking separate
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