共查询到20条相似文献,搜索用时 15 毫秒
1.
The parameterized node multiway cut problem is for a given graph to find a separator of size bounded by k whose removal separates a collection of terminal sets in the graph. In this paper, we develop an O(k4
k
n
3) time algorithm for this problem, significantly improving the previous algorithm of time
for the problem. Our result gives the first polynomial time algorithm for the minimum node multiway cut problem when the separator size is bounded by O(log n).
A preliminary version of this paper was presented at The 10th Workshop on Algorithms and Data Structures (WADS 2007).
This work was supported in part by the National Science Foundation under the Grants CCR-0311590 and CCF-0430683. 相似文献
2.
Jun Liu Zhongdan Huan Haiyang Huang Haili Zhang 《International Journal of Computer Vision》2009,85(2):182-191
In this paper, we present a new version of the famous Rudin-Osher-Fatemi (ROF) model to restore image. The key point of the
model is that it could reconstruct images with blur and non-uniformly distributed noise. We develop this approach by adding
several statistical control parameters to the cost functional, and these parameters could be adaptively determined by the
given observed image. In this way, we could adaptively balance the performance of the fit-to-data term and the regularization
term. The Numerical experiments have demonstrated the significant effectiveness and robustness of our model in restoring blurred
images with mixed Gaussian noise or salt-and-pepper noise. 相似文献
3.
An Improved Quality Function Deployment(QFD) Model 总被引:1,自引:0,他引:1
By introducing sequential and logical relationship factors into ASI (American SuppliersInstitute) Clausing/Makabe-QFD Model, a more practical model of QFD (Quality FunctionDeployment) is presented. Based on that the quality requirements are converted into designspecifications and technical measures step by step in this model, logical relationship factors canclassify the related Hows (how to do, the quality measures) into groups, each of which should belogical to individual What (what to do, the quality goal). Sequential factors can express theimplementing sequence of Hows. A feasibility evaluation method is proposed to eliminate the inferiorgroups of Hows. This improved QFD model can provide enough information to produce a practicalquality plan. 相似文献
4.
Jooyoung Hahn Xue-Cheng Tai Sofia Borok Alfred Marcel Bruckstein 《International Journal of Computer Vision》2011,92(3):308-324
In this paper, we propose an orientation-matching functional minimization for image denoising and image inpainting. Following
the two-step TV-Stokes algorithm (Rahman et al. in Scale space and variational methods in computer vision, pp. 473–482, Springer,
Heidelberg, 2007; Tai et al. in Image processing based on partial differential equations, pp. 3–22, Springer, Heidelberg, 2006; Bertalmio et al. in Proc. conf. comp. vision pattern rec., pp. 355–362, 2001), a regularized tangential vector field with zero divergence condition is first obtained. Then a novel approach to reconstruct
the image is proposed. Instead of finding an image that fits the regularized normal direction from the first step, we propose
to minimize an orientation matching cost measuring the alignment between the image gradient and the regularized normal direction.
This functional yields a new nonlinear partial differential equation (PDE) for reconstructing denoised and inpainted images.
The equation has an adaptive diffusivity depending on the orientation of the regularized normal vector field, providing reconstructed
images which have sharp edges and smooth regions. The additive operator splitting (AOS) scheme is used for discretizing Euler-Lagrange
equations. We present the results of various numerical experiments that illustrate the improvements obtained with the new
functional. 相似文献
5.
Image Fusion for Enhanced Visualization: A Variational Approach 总被引:3,自引:0,他引:3
Gemma Piella 《International Journal of Computer Vision》2009,83(1):1-11
We present a variational model to perform the fusion of an arbitrary number of images while preserving the salient information
and enhancing the contrast for visualization. We propose to use the structure tensor to simultaneously describe the geometry
of all the inputs. The basic idea is that the fused image should have a structure tensor which approximates the structure
tensor obtained from the multiple inputs. At the same time, the fused image should appear ‘natural’ and ‘sharp’ to a human
interpreter. We therefore propose to combine the geometry merging of the inputs with perceptual enhancement and intensity
correction. This is performed through a minimization functional approach which implicitly takes into account a set of human
vision characteristics. 相似文献
6.
Ming Lei Pilian He Zhichao Li 《通讯和计算机》2006,3(8):20-24
Most of the earlier work on clustering is mainly focused on numerical data the inherent geometric properties of which can be exploited to naturally define distance functions between the data points. However, the computational cost makes most of the previous algorithms unacceptable for clustering very large databases. The k-means algorithm is well known for its efficiency in this respect. At the same time, working only on numerical data prohibits them from being used for clustering categorical data. This paper shows how to apply the notion of "cluster centers" to a dataset of categorical objects, and a k-means-like algorithm for clustering categorical data is introduced. 相似文献
7.
Zhou Qihai 《计算机科学技术学报》1991,6(2):205-208
In this paper,an improved graphic representation for Structured Program Design--N-S-Z (Nassi-Shneiderman-Zhou Diagram) is proposed.It not only preserves the advantages of the conventional graphic and non-graphic representations,but also adds some new features which will enhance the representative power of the original diagram. 相似文献
8.
Wenyuan Wang Haibo Xu Suhua Wei 《通讯和计算机》2005,2(9):36-40,66
In this paper, we develop a new active contour model for image selective segmentation. The model adopts cascade anisotropic diffusion prcprocessing and a selective term in level set function. Cascade anisotropic diffusion filtering is powerful and tlexible to enhance image for various segmentation tasks. The selective term in level set function can evolve a single curve to capture a selective segmentation region which we are interested in. This is useful for intentional segmentatioa tasks. We ,:an al, so realize the multi-region segmentation by varying selecting term conditions. Furthermore, we obviously speed the process of the new algorithm by using AOS scheme in cascade anisotropic diffusion filtering aad discarding mean curvature motiou in level set function. We illustrate the performance of our segmentation method on images generated by different modalities. 相似文献
9.
Consider a set of labels L and a set of unordered trees \(\mathcal{T}=\{\mathcal{T}^{(1)},\mathcal{T}^{(2)},\ldots ,\allowbreak \mathcal{T}^{(k)}\}\) where each tree \(\mathcal{T}^{(i)}\) is distinctly leaf-labeled by some subset of L. One fundamental problem is to find the biggest tree (denoted as supertree) to represent \(\mathcal{T}\) which minimizes the disagreements with the trees in \(\mathcal{T}\) under certain criteria. In this paper, we focus on two particular supertree problems, namely, the maximum agreement supertree problem (MASP) and the maximum compatible supertree problem (MCSP). These two problems are known to be NP-hard for k≥3. This paper gives improved algorithms for both MASP and MCSP. In particular, our results imply the first polynomial time algorithms for both MASP and MCSP when both k and the maximum degree D of the input trees are constant. 相似文献
10.
Mingyu Xiao 《Theory of Computing Systems》2010,46(4):723-736
Given a graph G=(V,E) with n vertices and m edges, and a subset T of k vertices called terminals, the Edge (respectively, Vertex) Multiterminal Cut problem is to find a set of at most l edges (non-terminal vertices), whose removal from G separates each terminal from all the others. These two problems are NP-hard for k≥3 but well-known to be polynomial-time solvable for k=2 by the flow technique. In this paper, based on a notion farthest minimum isolating cut, we design several simple and improved algorithms for Multiterminal Cut. We show that Edge Multiterminal Cut can be solved in O(2 l kT(n,m)) time and Vertex Multiterminal Cut can be solved in O(k l T(n,m)) time, where T(n,m)=O(min?(n 2/3,m 1/2)m) is the running time of finding a minimum (s,t) cut in an unweighted graph. Furthermore, the running time bounds of our algorithms can be further reduced for small values of k: Edge 3-Terminal Cut can be solved in O(1.415 l T(n,m)) time, and Vertex {3,4,5,6}-Terminal Cuts can be solved in O(2.059 l T(n,m)), O(2.772 l T(n,m)), O(3.349 l T(n,m)) and O(3.857 l T(n,m)) time respectively. Our results on Multiterminal Cut can also be used to obtain faster algorithms for Multicut: $O((\min(\sqrt{2k},l)+1)^{2k}2^{l}T(n,m))Given a graph G=(V,E) with n vertices and m edges, and a subset T of k vertices called terminals, the Edge (respectively, Vertex) Multiterminal Cut problem is to find a set of at most l edges (non-terminal vertices), whose removal from G separates each terminal from all the others. These two problems are NP-hard for k≥3 but well-known to be polynomial-time solvable for k=2 by the flow technique. In this paper, based on a notion farthest minimum isolating cut, we design several simple and improved algorithms for Multiterminal Cut. We show that Edge Multiterminal Cut can be solved
in O(2
l
kT(n,m)) time and Vertex Multiterminal Cut can be solved in O(k
l
T(n,m)) time, where T(n,m)=O(min (n
2/3,m
1/2)m) is the running time of finding a minimum (s,t) cut in an unweighted graph. Furthermore, the running time bounds of our algorithms can be further reduced for small values
of k: Edge 3-Terminal Cut can be solved in O(1.415
l
T(n,m)) time, and Vertex {3,4,5,6}-Terminal Cuts can be solved in O(2.059
l
T(n,m)), O(2.772
l
T(n,m)), O(3.349
l
T(n,m)) and O(3.857
l
T(n,m)) time respectively. Our results on Multiterminal Cut can also be used to obtain faster algorithms for Multicut:
O((min(?{2k},l)+1)2k2lT(n,m))O((\min(\sqrt{2k},l)+1)^{2k}2^{l}T(n,m))
-time algorithm for Edge Multicut and O((2k)
k+l/2
T(n,m))-time algorithm for Vertex Multicut. 相似文献
11.
Equational programming language (EP) is a novel intelligence language.This paper describes our EP system based on equational logic.Its execution mechanism is pattern matching.The paper focuses the discussion on the improvement to bottom-up tree pattern matching.The new bottom-up method shows high execution efficiency. 相似文献
12.
In recent years we have seen a tremendous growth in the amount of freely available 3D content, in part due to breakthroughs for 3D model design and acquisition. For example, advances in range sensor technology and design software have dramatically reduced the manual labor required to construct 3D models. As collections of 3D content continue to grow rapidly, the ability to perform fast and accurate retrieval from a database of models has become a necessity. At the core of this retrieval task is the fundamental challenge of defining and evaluating similarity between 3D shapes. Some effective methods dealing with this challenge consider similarity measures based on the visual appearance of models. While collections of rendered images are discriminative for retrieval tasks, such representations come with a few inherent limitations such as restrictions in the image viewpoint sampling and high computational costs. In this paper we present a novel algorithm for model similarity that addresses these issues. Our proposed method exploits techniques from spherical signal processing to efficiently evaluate a visual similarity measure between models. Extensive evaluations on multiple datasets are provided. 相似文献
13.
Yoshifumi Sakai 《Theory of Computing Systems》2011,48(1):189-210
The sparse spliced alignment problem consists of finding a chain of zero or more exons from O(n) prescribed candidate exons of a DNA sequence of length O(n) that is most similar to a known related gene sequence of length n. This study improves the running time of the fastest known algorithm for this problem to date, which executes in O(n
2.25) time, or very recently, in O(n
2log 2
n) time, by proposing an O(n
2log n)-time algorithm. 相似文献
14.
Shishir K. Shah 《International Journal of Computer Vision》2008,80(1):92-103
This paper presents a probabilistic framework based on Bayesian theory for the performance prediction and selection of an
optimal segmentation algorithm. The framework models the optimal algorithm selection process as one that accounts for the
information content of an input image as well as the behavioral properties of a particular candidate segmentation algorithm.
The input image information content is measured in terms of image features while the candidate segmentation algorithm’s behavioral
characteristics are captured through the use of segmentation quality features. Gaussian probability distribution models are
used to learn the required relationships between the extracted image and algorithm features and the framework tested on the
Berkeley Segmentation Dataset using four candidate segmentation algorithms. 相似文献
15.
Vinay Shet Maneesh Singh Claus Bahlmann Visvanathan Ramesh Jan Neumann Larry Davis 《International Journal of Computer Vision》2011,93(2):141-161
Predicate logic based reasoning approaches provide a means of formally specifying domain knowledge and manipulating symbolic
information to explicitly reason about different concepts of interest. Extension of traditional binary predicate logics with
the bilattice formalism permits the handling of uncertainty in reasoning, thereby facilitating their application to computer
vision problems. In this paper, we propose using first order predicate logics, extended with a bilattice based uncertainty
handling formalism, as a means of formally encoding pattern grammars, to parse a set of image features, and detect the presence
of different patterns of interest. Detections from low level feature detectors are treated as logical facts and, in conjunction
with logical rules, used to drive the reasoning. Positive and negative information from different sources, as well as uncertainties
from detections, are integrated within the bilattice framework. We show that this approach can also generate proofs or justifications
(in the form of parse trees) for each hypothesis it proposes thus permitting direct analysis of the final solution in linguistic
form. Automated logical rule weight learning is an important aspect of the application of such systems in the computer vision
domain. We propose a rule weight optimization method which casts the instantiated inference tree as a knowledge-based neural
network, interprets rule uncertainties as link weights in the network, and applies a constrained, back-propagation algorithm
to converge upon a set of rule weights that give optimal performance within the bilattice framework. Finally, we evaluate
the proposed predicate logic based pattern grammar formulation via application to the problems of (a) detecting the presence
of humans under partial occlusions and (b) detecting large complex man made structures as viewed in satellite imagery. We
also evaluate the optimization approach on real as well as simulated data and show favorable results. 相似文献
16.
In this paper, we present feature/detail preserving models for color image smoothing and segmentation using the Hamiltonian
quaternion framework. First, we introduce a novel quaternionic Gabor filter (QGF) which can combine the color channels and
the orientations in the image plane. We show that these filters are optimally localized both in the spatial and frequency
domains and provide a good approximation to quaternionic quadrature filters. Using the QGFs, we extract the local orientation
information in the color images. Second, in order to model this derived orientation information, we propose continuous mixtures
of appropriate exponential basis functions and derive analytic expressions for these models. These analytic expressions take
the form of spatially varying kernels which, when convolved with a color image or the signed distance function of an evolving
contour (placed in the color image), yield a detail preserving smoothing and segmentation, respectively. Several examples
on widely used image databases are shown to depict the performance of our algorithms. 相似文献
17.
Giorgos Sfikas Christophoros Nikou Nikolaos Galatsanos Christian Heinrich 《Journal of Mathematical Imaging and Vision》2010,36(2):91-110
Spatially varying mixture models are characterized by the dependence of their mixing proportions on location (contextual mixing proportions) and they have been widely used in image segmentation. In this work, Gauss-Markov random field (MRF) priors are employed
along with spatially varying mixture models to ensure the preservation of region boundaries in image segmentation. To preserve
region boundaries, two distinct models for a line process involved in the MRF prior are proposed. The first model considers
edge preservation by imposing a Bernoulli prior on the normally distributed local differences of the contextual mixing proportions. It is a discrete line process model whose parameters are computed by variational inference. The second model imposes Gamma
prior on the Student’s-t distributed local differences of the contextual mixing proportions. It is a continuous line process whose parameters are also automatically estimated by the Expectation-Maximization (EM) algorithm.
The proposed models are numerically evaluated and two important issues in image segmentation by mixture models are also investigated
and discussed: the constraints to be imposed on the contextual mixing proportions to be probability vectors and the MRF optimization
strategy in the frameworks of the standard and variational EM algorithm. 相似文献
18.
Sébastien Bougleux Abderrahim Elmoataz Mahmoud Melkemi 《International Journal of Computer Vision》2009,84(2):220-236
We propose a discrete regularization framework on weighted graphs of arbitrary topology, which unifies local and nonlocal
processing of images, meshes, and more generally discrete data. The approach considers the problem as a variational one, which
consists in minimizing a weighted sum of two energy terms: a regularization one that uses the discrete p-Dirichlet form, and an approximation one. The proposed model is parametrized by the degree p of regularity, by the graph structure and by the weight function. The minimization solution leads to a family of simple linear
and nonlinear processing methods. In particular, this family includes the exact expression or the discrete version of several
neighborhood filters, such as the bilateral and the nonlocal means filter. In the context of images, local and nonlocal regularizations,
based on the total variation models, are the continuous analog of the proposed model. Indirectly and naturally, it provides
a discrete extension of these regularization methods for any discrete data or functions. 相似文献
19.
As early as in 1975, Shamos and Hoey first gave an O(n lg n)-time divide-and-conquer algorithm (Stt algorithm in short) for the problem of finding the closest pair of points. In one process of combination, the Euclidean distances between 3n pairs of points need to be computed, so the overall complexity of computing distance is then 3n lgn. Since the computation of distance is more costly compared with other basic operation, how to improve SH algorithm from the aspect of complexity of computing distance is considered. In 1998, Zhou, Xiong and Zhu improved SH algorithm by reducing this complexity to 2n lg n. In this paper, we make further improvement. The overall complexity of computing distances is reduced to (3n lg n)/2, which is only half that of SH algorithm. 相似文献
20.
This paper presents a further improved Production Activity Control Architecture to deal with the complexity of information by creating Sub-Producers and Sub-Movers which will not only give a better control at workstation level but also reduce load on the Dispatcher. It also makes an analysis of the basic and improved PAC (Production Activity Control) Architecture in the Control System for Integrated Manufacturing. The PAC Architecture and the improvement will further enhance the flexibility and adaptability of the architecture in the ever changing environment of the Shop Floor Control (SFC) Systems. 相似文献