Discrete Gaussian measures and new bounds of the smoothing parameter for lattices

Author(s):  
Zhongxiang Zheng ◽  
Chunhuan Zhao ◽  
Guangwu Xu
2013 ◽  
Vol 05 (02) ◽  
pp. 205-223 ◽  
Author(s):  
ISHAY HAVIV ◽  
ODED REGEV

We show that for every n-dimensional lattice [Formula: see text] the torus [Formula: see text] can be embedded with distortion [Formula: see text] into a Hilbert space. This improves the exponential upper bound of O(n3n/2) due to Khot and Naor (FOCS 2005, Math. Ann. 2006) and gets close to their lower bound of [Formula: see text]. We also obtain tight bounds for certain families of lattices. Our main new ingredient is an embedding that maps any point [Formula: see text] to a Gaussian function centered at u in the Hilbert space [Formula: see text]. The proofs involve Gaussian measures on lattices, the smoothing parameter of lattices and Korkine–Zolotarev bases.


Author(s):  
Xiang Ma ◽  
Xuemei Li ◽  
Yuanfeng Zhou ◽  
Caiming Zhang

AbstractSmoothing images, especially with rich texture, is an important problem in computer vision. Obtaining an ideal result is difficult due to complexity, irregularity, and anisotropicity of the texture. Besides, some properties are shared by the texture and the structure in an image. It is a hard compromise to retain structure and simultaneously remove texture. To create an ideal algorithm for image smoothing, we face three problems. For images with rich textures, the smoothing effect should be enhanced. We should overcome inconsistency of smoothing results in different parts of the image. It is necessary to create a method to evaluate the smoothing effect. We apply texture pre-removal based on global sparse decomposition with a variable smoothing parameter to solve the first two problems. A parametric surface constructed by an improved Bessel method is used to determine the smoothing parameter. Three evaluation measures: edge integrity rate, texture removal rate, and gradient value distribution are proposed to cope with the third problem. We use the alternating direction method of multipliers to complete the whole algorithm and obtain the results. Experiments show that our algorithm is better than existing algorithms both visually and quantitatively. We also demonstrate our method’s ability in other applications such as clip-art compression artifact removal and content-aware image manipulation.


Author(s):  
Lázió Györfi ◽  
Wolfgang Härdle ◽  
Pascal Sarda ◽  
Philippe Vieu
Keyword(s):  

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