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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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Sparse time-frequency representation of nonlinear and nonstationary data Dedicated to Professor Shi Zhong-Ci on the Occasion of his 80th Birthday 被引量:7
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作者 HOU Thomas Yizhao SHI ZuoQiang 《Science China Mathematics》 SCIE 2013年第12期2489-2506,共18页
Adaptive data analysis provides an important tool in extracting hidden physical information from multiscale data that arise from various applications. In this paper, we review two data-driven time-frequency analysis m... Adaptive data analysis provides an important tool in extracting hidden physical information from multiscale data that arise from various applications. In this paper, we review two data-driven time-frequency analysis methods that we introduced recently to study trend and instantaneous frequency of nonlinear and nonstationary data. These methods are inspired by the empirical mode decomposition method (EMD) and the recently developed compressed (compressive) sensing theory. The main idea is to look for the sparsest representation of multiscale data within the largest possible dictionary consisting of intrinsic mode functions of the form {a(t) cos(0(t))}, where a is assumed to be less oscillatory than cos(θ(t)) and θ '≥ 0. This problem can be formulated as a nonlinear ι0 optimization problem. We have proposed two methods to solve this nonlinear optimization problem. The first one is based on nonlinear basis pursuit and the second one is based on nonlinear matching pursuit. Convergence analysis has been carried out for the nonlinear matching pursuit method. Some numerical experiments are given to demonstrate the effectiveness of the proposed methods. 展开更多
关键词 sparse representation time-frequency analysis DATA-DRIVEN
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