基于2DGE图像先验的蛋白质点检测方法

各种改进的分水岭变换是目前应用最广的二维凝胶电泳(2DGE)图像蛋白质点分割算法.其中标记控制分水岭分割效果较好,但由于忽略了蛋白质点大小和形状,导致外标记落在部分蛋白质点区域内而无法正确分割.针对该问题,提出一种结合2DGE先验的分水岭分割方法.首先,根据2DGE图像蛋白质点中心灰度极小先验提取中心标记,并通过中心标记膨胀提取距离标记;然后,根据2DGE图像背景灰度极大先验,在距离标记划分的区块内提取原始2DGE图的局部自然分区标记,并对二者进行融合优化,获得最佳背景标记;最后在梯度图像各区块内进行分水岭变换,提取蛋白质点边缘.通过对四组真实扫描2DGE图像进行实验,结果表明,该方法明显改善了蛋白质点边缘检测正确率.     

Unsupervised Multiphase Segmentation: A Phase Balancing Model

Variational models have been studied for image segmentation application since the Mumford-Shah functional was introduced in the late 1980s. In this paper, we focus on multiphase segmentation with a new regularization term that yields an unsupervised segmentation model. We propose a functional that automatically chooses a favorable number of phases as it segments the image. The primary driving force of the segmentation is the intensity fitting term while a phase scale measure complements the regularization term. We propose a fast, yet simple, brute-force numerical algorithm and present experimental results showing the robustness and stability of the proposed model.     

Hierarchical Segmentation for Hardware Function Evaluation

This paper presents a method for evaluating functions based on piecewise polynomial approximations (splines) with a hierarchical segmentation scheme targeting hardware implementation. The methodology provides significant reduction in table size compared to traditional uniform segmentation approaches. The use of hierarchies involving uniform splines and splines with size varying by powers of two is particularly well suited for the coverage of nonlinear regions. The segmentation step is automated and supports user-supplied precision requirements and approximation method. Bit-widths of the coefficients and arithmetic operators are optimized to minimize circuit area and enable a guarantee of 1 unit in the last place (ulp) accuracy at the output. A coefficient transformation technique is also described, which significantly reduces the dynamic ranges of the fixed-point polynomial coefficients. The hierarchical segmentation method is illustrated using a set of functions including $-(x/2) log_2{x}, cos^{-1}(x), sqrt{-ln(x)}$ , a high-degree rational function, $ln(1+x)$, and $1/(1+x)$. Various degree-1 and degree-2 approximation results for precisions between 8 to 24 bits are given. Hardware realizations are demonstrated on a Xilinx Virtex-4 field-programmable gate array (FPGA).      

基于广义Gibbs先验的优质PET成像

 最大后验方法(Maximum a posteriori, MAP)已经广泛应用于解决图像重建中的病态问题,正电子发射成像(Positron emission tomography, PET)便是其中之一。本文基于MAP方法,针对PET成像提出一新的基于图像相似结构信息的广义Gibbs先验形式,新先验能在有效地抑制噪声的同时,鲁棒地保持锐利的边缘信息。但由于新先验的引入,使得重建模型的求解趋于复杂。为解决模型解的收敛性问题,我们提出两步式的局部线化优化迭代重建策略,并结合抛物线替代坐标上升(Paraboloidal surrogate coordinate ascent,PSCA)算法进行求解。新算法分别对PET模拟数据和真实数据进行重建实验,结果表明本文提出的基于广义Gibbs先验的PET成像可以获得优质的重建图像。     

一种基于灰度分割的调焦评价函数

提出一种新的基于灰度分割的调焦评价函数.该函数利用清晰图像的灰度变化比模糊图像频繁的原理,以待调焦区域灰度均值作为其变化中心,并以该中心进行分割,最终计算出灰度围绕中心的变化频度作为评价函数值.比较了该函数和其他评价函数的效果.实验证明,该函数满足调焦评价函数的要求,可以在实际工程中较好的应用.     

A Unified Framework for Automated 3-D Segmentation of Surface-Stained Living Cells and a Comprehensive Segmentation Evaluation

This work presents a unified framework for whole cell segmentation of surface stained living cells from 3-D data sets of fluorescent images. Every step of the process is described, image acquisition, prefiltering, ridge enhancement, cell segmentation, and a segmentation evaluation. The segmentation results from two different automated approaches for segmentation are compared to manual segmentation of the same data using a rigorous evaluation scheme. This revealed that combination of the respective cell types with the most suitable microscopy method resulted in high success rates up to 97%. The described approach permits to automatically perform a statistical analysis of various parameters from living cells.     

风险评估打开信息安全金刚钻

2005年12月16日,黄菊副总理主持国家网络与信息安全协调小组会议,专门研究了信息安全风险评估问题,审议通过了《关于开展信息安全风险评估工作的意见》。这是我国信息安全保障工作中的一件大事。     

Comparison and Evaluation of Methods for Liver Segmentation From CT Datasets

This paper presents a comparison study between 10 automatic and six interactive methods for liver segmentation from contrast-enhanced CT images. It is based on results from the “MICCAI 2007 Grand Challenge” workshop, where 16 teams evaluated their algorithms on a common database. A collection of 20 clinical images with reference segmentations was provided to train and tune algorithms in advance. Participants were also allowed to use additional proprietary training data for that purpose. All teams then had to apply their methods to 10 test datasets and submit the obtained results. Employed algorithms include statistical shape models, atlas registration, level-sets, graph-cuts and rule-based systems. All results were compared to reference segmentations five error measures that highlight different aspects of segmentation accuracy. All measures were combined according to a specific scoring system relating the obtained values to human expert variability. In general, interactive methods reached higher average scores than automatic approaches and featured a better consistency of segmentation quality. However, the best automatic methods (mainly based on statistical shape models with some additional free deformation) could compete well on the majority of test images. The study provides an insight in performance of different segmentation approaches under real-world conditions and highlights achievements and limitations of current image analysis techniques.      

Distributed Topology Control Algorithm Based on Load Balancing Evaluation Model in Wireless Sensor Networks

Wireless Personal Communications - In wireless sensor networks, the unbalanced load of nodes is easy to cause low energy nodes die prematurely. It may lead network collapse. According to the...     

三种分割算法在BGA焊点图像分割中的应用

x射线BGA焊点检测图像中,存在大量与检测无关的冗余信息。针对这一问题,从原理和应用效果上对三种基本阈值分割算法进行了对比分析并进行仿真实验。通过对三种分割算法的比较,得到了较为通用的算法,效果令人满意。     

基于特征区域分割的立体视频视觉舒适度评价方法

为准确反映人眼在观看立体视频过程中的视觉舒适程度,提出了一种基于特征区域分割的立体视频视觉舒适度评价方法。首先自适应地分割提取出立体视频序列中的人眼的感兴趣区域,以及相邻帧间的运动区域,然后结合深度感知理论和空间合并技术,对视觉舒适度这一特征量进行建模,最后实现对立体视频视觉舒适度的评定。实验结果表明,使用本文的方法对立体视频视觉舒适度进行评价,可以很好的模拟人眼直接观测的视觉感受,对于视觉舒适度的研究具有重要的参考价值。     

基于分割评价的多层次自适应双阈值分割算法

 论文通过分析最大信息熵双阈值分割算法原理,根据先验知识,设置目标出现最小最大频度条件,改变自适应双阈值计算条件,加快计算速度.同时通过计算分割后各个目标相关特征,利用BP神经网络技术对每个目标进行评价,根据评价结果修改原输入图像相应目标区域,并引入多层次迭代机制,实现了图像的多层次综合分割.实验结果表明,基于分割评价的多层次自适应双阈值分割算法提高了算法的通用性和分割的精确性,但是算法复杂性增加.     

Bayesian Source Separation of Linear and Linear-quadratic Mixtures Using Truncated Priors

In this work, we propose a Bayesian source separation method of linear-quadratic (LQ) and linear mixtures. Since our method relies on truncated prior distributions, it is particularly useful when the bounds of the sources and of the mixing coefficients are known in advance; this is the case, for instance, in non-negative matrix factorization. To implement our idea, we consider a Gibbs’ sampler equipped with latent variables, which are set to simplify the sampling steps. Experiments with synthetic data point out that the new proposal performs well in situations where classical ICA-based solutions fail to separate the sources. Moreover, in order to illustrate the application of our method to actual data, we consider the problem of separating scanned images.     

Dirichlet Priors for MAP Inference of Protein Conformation Abundances from SAXS

Estimation of mixture coefficients of protein conformations in solution find applications in understanding protein behavior. We describe a method for maximum a posteriori (MAP) estimation of the mixture coefficients of ensemble of conformations in a protein mixture solution using measured small angle X-ray scattering (SAXS) intensities. The proposed method builds upon a model for the measurements of crystallographically determined conformations. Assuming that a priori information on the protein mixture is available, and that priori information follows a Dirichlet distribution, we develop a method to estimate the relative abundances with MAP estimator. The Dirichlet distribution depends on concentration parameters which may not be known in practice and thus need to be estimated. To estimate these unknown concentration parameters we developed an expectation-maximization (EM) method. Adenylate kinase (ADK) protein was selected as the test bed due to its known conformations Beckstein et al. (Journal of Molecular Biology, 394(1), 160 1). Known conformations are assumed to form the full vector bases that span the measurement space. In Monte Carlo simulations, mixture coefficient estimation performances of MAP and maximum likelihood (ML) (which assumes a uniform prior on the mixture coefficients) estimators are compared. MAP estimators using known and unknown concentration parameters are also compared in terms of estimation performances. The results show that prior knowledge improves estimation accuracy, but performance is sensitive to perturbations in the Dirichlet distribution’s concentration parameters. Moreover, the estimation method based on EM algorithm shows comparable results to approximately known prior parameters.     

图像分割中的边缘检测

数字图像的边缘检测在图像分割、模式识别、机器视觉等中有很重要的作用。从70年代到现在发展出了很多种边缘检测的方法,而对于不同的应用环境,不同算法的效果不同。针对高速公路中图像的特点,对几种典型的边缘检测方法的原理和实现方法进行了详细分析和说明,对比分析了各种算法应用在高速公路图像识别中的优劣,并根据高速公路图像识别系统的特点选择了合适的检测算法。     

基于BP神经网络评价的图像闭环控制迭代分割算法

论文在分析闭环控制分割原理与OTSU算法基础上提出了一种新的分割算法.通过监督训练BP网络实现了局部分割结果评价,并根据评价结果对每个目标区域进行了平滑与擦除处理,同时增加先验目标点出现的最小最大频度参数,实现OTSU算法的闭环参数控制,然后引入迭代机制实现图像的综合分割.最后论文将算法用于显微镜细胞图像分割,试验表明该算法可以大大改善分割效果.     

无线局域网中的负载均衡技术

随着无线局域网扩展服务集中的终端（STA）的移动和无线信道的时变，各个接入点（AP）上的负载会出现差异，需要加强负载均衡，平衡各个AP的差异，以达到最大化的网络资源利用。无线局域网中的负载均衡算法可以采用STA／AP主控负载均衡或接入式／切换式负载均衡技术。在时分双工的时分同步码分多址（TD—SCDMA）系统中，由于系统在最小资源单位和媒体访问机制等方面的差异，负载均衡可以在小到时隙和码道，大到终端和小区等不同的级别上进行，体现码分多址（CDMA）和时分双工（TDD）的特点，具体方式更加灵活多样。     

Balancing sets of vectors

For n>0, d⩾0, n≡d (mod 2), let K(n, d) denote the minimal cardinality of a family V of ±1 vectors of dimension n, such that for any ±1 vector w of dimension n there is a v∈V such that |v- w|⩽d, where v-w is the usual scalar product of v and w. A generalization of a simple construction due to D.E. Knuth (1986) shows that K(n , d)⩽[n/(d+1)]. A linear algebra proof is given here that this construction is optimal, so that K(n, d)-[n/(d+1)] for all n≡d (mod 2). This construction and its extensions have applications to communication theory, especially to the construction of signal sets for optical data links     

Segmentation of microcalcifications in mammograms

A systematic method for the detection and segmentation of microcalcifications in mammograms is presented. It is important to preserve size and shape of the individual calcifications as exactly as possible. A reliable diagnosis requires both rates of false positives as well as false negatives to be extremely low. The proposed approach uses a two-stage algorithm for spot detection and shape extraction. The first stage applies a weighted difference of Gaussians filter for the noise-invariant and size-specific detection of spots. A morphological filter reproduces the shape of the spots. The results of both filters are combined with a conditional thickening operation. The topology and the number of the spots are determined with the first filter, and the shape by means of the second. The algorithm is tested with a series of real mammograms, using identical parameter values for all images. The results are compared with the judgement of radiological experts, and they are very encouraging. The described approach opens up the possibility of a reproducible segmentation of microcalcifications, which is a necessary precondition for an efficient screening program.