Active contours driven by Cuckoo Search strategy for brain tumour images segmentation

In this paper, an alternative Active Contour Model (ACM) driven by Multi-population Cuckoo Search (CS) algorithm is introduced. This strategy assists the converging of control points towards the global minimum of the energy function, unlike the traditional ACM version which is often trapped in a local minimum. In the proposed methodology, each control point is constrained in a local search window, and its energy minimisation is performed through a Cuckoo Search via Lévy flights paradigm. With respect to local search window, two shape approaches have been considered: rectangular shape and polar coordinates. Results showed that the CS method using polar coordinates is generally preferable to CS performed in rectangular shapes. Real medical and synthetic images were used to validate the proposed strategy, through three performance metrics as the Jaccard index, the Dice index and the Hausdorff distance. Applied specifically to Magnetic Resonance Imaging (MRI) images, the proposed method enables to reach better accuracy performance than the traditional ACM formulation, also known as Snakes and the use of Multi-population Particle Swarm Optimisation (PSO) algorithm.     

Image segmentation techniques

There are now a wide variety of image segmentation techniques, some considered general purpose and some designed for specific classes of images. These techniques can be classified as: measurement space guided spatial clustering, single linkage region growing schemes, hybrid linkage region growing schemes, centroid linkage region growing schemes, spatial clustering schemes, and split-and-merge schemes. In this paper, each of the major classes of image segmentation techniques is defined and several specific examples of each class of algorithm are described. The techniques are illustrated with examples of segmentations performed on real images.     

Image segmentation functional model

We propose a new approach of the image segmentation methods. This approach is based on a functional model composed of five elementary blocks called in an iterative process. Different segmentation methods can be decomposed with such a scheme and lead to elementary building blocks with unified functionality and interfaces. We present the decompositions of three segmentation methods and the implementation results, which illustrate the potential of the proposed model. This generic model is a common framework, which makes segmentation techniques more readable and offers new perspectives for the development, the comparison and the implementation of segmentation methods.     

基于分割块的图像语义分割方法

针对复杂室外环境下,传统语义分割模型无法准确描述对象轮廓的问题,提出了采用结构森林法生成边缘概率,运用分水岭算法将边缘概率转化成初始割块.为避免过分分割,利用超度量轮廓图算法选取适当阈值生成分割块以获取更准确的轮廓信息,通过随机森林训练分割块,得到语义分割结果.实验结果表明:在处理复杂的语义分割任务时,基于分割块的方法在精度、鲁棒性和速率方面均具有良好表现.     

A classification-based review recommender

Many online stores encourage their users to submit product or service reviews in order to guide future purchasing decisions. These reviews are often listed alongside product recommendations but, to date, limited attention has been paid as to how best to present these reviews to the end-user. In this paper, we describe a supervised classification approach that is designed to identify and recommend the most helpful product reviews. Using the TripAdvisor service as a case study, we compare the performance of several classification techniques using a range of features derived from hotel reviews. We then describe how these classifiers can be used as the basis for a practical recommender that automatically suggests the most-helpful contrasting reviews to end-users. We present an empirical evaluation which shows that our approach achieves a statistically significant improvement over alternative review ranking schemes.     

Image segmentation with ratio cut

This paper proposes a new cost function, cut ratio, for segmenting images using graph-based methods. The cut ratio is defined as the ratio of the corresponding sums of two different weights of edges along the cut boundary and models the mean affinity between the segments separated by the boundary per unit boundary length. This new cost function allows the image perimeter to be segmented, guarantees that the segments produced by bipartitioning are connected, and does not introduce a size, shape, smoothness, or boundary-length bias. The latter allows it to produce segmentations where boundaries are aligned with image edges. Furthermore, the cut-ratio cost function allows efficient iterated region-based segmentation as well as pixel-based segmentation. These properties may be useful for some image-segmentation applications. While the problem of finding a minimum ratio cut in an arbitrary graph is NP-hard, one can find a minimum ratio cut in the connected planar graphs that arise during image segmentation in polynomial time. While the cut ratio, alone, is not sufficient as a baseline method for image segmentation, it forms a good basis for an extended method of image segmentation when combined with a small number of standard techniques. We present an implemented algorithm for finding a minimum ratio cut, prove its correctness, discuss its application to image segmentation, and present the results of segmenting a number of medical and natural images using our techniques.     

Image segmentation using evolutionary computation

Image segmentation denotes a process by which a raw input image is partitioned into nonoverlapping regions such that each region is homogeneous and the union of any two adjacent regions is heterogeneous. A segmented image is considered to be the highest domain-independent abstraction of an input image. The image segmentation problem is treated as one of combinatorial optimization. A cost function which incorporates both edge information and region gray-scale uniformity is defined. The cost function is shown to be multivariate with several local minima. The genetic algorithm, a stochastic optimization technique based on evolutionary computation, is explored in the context of image segmentation. A class of hybrid evolutionary optimization algorithms based on a combination of the genetic algorithm and stochastic annealing algorithms such as simulated annealing, microcanonical annealing, and the random cost algorithm is shown to exhibit superior performance as compared with the canonical genetic algorithm. Experimental results on gray-scale images are presented     

Image segmentation by pixel classification

A fast boundary finding algorithm is presented which works without threshold operation and without any interactive control. The procedure can be described as a hierarchical two-step algorithm. In the first step the image is divided into two disjunct regions, one of them including the whole object of interest.In the second step the problem of boundary finding is suggested as a classification problem, which means that for any pixel a four-dimensional feature vector is computed which allows classification of pixels into contour elements and any other pixels.The algorithm was tested on several thousand cell images and can be easily adapted to other problems by modification of a set of parameters.     

Image segmentation with directed trees

This correspondence presents a simple algorithm to detect and label homogeneous areas in an image, using directed trees for region labeling. The scheme constructs directed trees with the image points as nodes, guided by an edge value computed at every point. These directed trees segment the image into disjoint regions. Because of a valley seeldng property of the tree construction procedure, the boundaries separating the resultant segments pass through the center of the edges. The algorithm thus performs wel1 with thick and wide edges of varying height, because no thresholding of the edge image is involved. The properties of the resultant segments are stated in terms of the edge image. The algorithm is shown to be simple, efficient, and effective for detecting homogeneous segments in the presence of noise. Results of application in the algorithm to segment a LANDSAT multispectral scene of an agricultural area are included.     

基于玻耳兹曼熵分析的图像分割方法研究*

根据热力学玻耳兹曼熵关系式,定义基于图像灰度谱的玻耳兹曼熵谱,将图像空间局部结构隐含于灰度谱的客观事实与玻耳兹曼熵谱联系在一起。最后在像素近邻空间进行统计计算,通过识别玻耳兹曼熵谱特征,实现图像分割。实验与比较分析表明,该方法具有显著优势。     

基于PSO算法的图像分割方法

针对大多数图像分割方法计算量大、不利于实时处理的缺点,提出用微粒群算法（PSO）优化最小误差分割方法.该方法不但具备最小误差分割法受目标和噪声影响小以及对小图像分割效果好的优点,还克服了遗传算法等加速算法需要预先设定众多运行参数,受目标变化影响大的问题.图像分割的效果和速度得到了提高,性能也更加稳定.实验结果反映了该方法的有效性.     

Image segmentation by a multiresolution approach

Multiresolution approaches to computer vision are able to rapidly detect and extract global structures from an image. In this paper we present (a) a pyramid-based algorithm that can detect the bimodality of the population of pixels in a grey level digital image and (b) a pyramid-based algorithm that maps the values of a bimodal population into two constant values which are approximately the means of the two component subpopulations. A population is considered bimodal if it can be divided into two component subpopulations whose variances are small relative to the population variance. An improvement to the above algorithm, which uses an iterative scheme, is also given, as well as some examples of segmented images. Both algorithms require processing times on the order of the logarithm of the population size.     

基于等周算法的图像分割

采用一种基于图论的等周算法对图像的分割进行了研究。首先利用等周算法对静止图像进行分割,并与边缘检测和区域检测的两种分割方法进行结果比较;接着利用等周算法并结合数学形态学处理对图像序列的分割进行了研究。实验结果表明：等周算法不仅可用于静止图像的分割,也可应用于图像序列的分割。基于等周算法可获取更为精确的分割结果,是一种快速的图论分割方法。并且结合形态学处理可对低对比度的目标获取好的分割结果。     

Image segmentation as an estimation problem

Picture segmentation is expressed as a sequence of decision problems with the framework of a split-and-merge algorithm. First regions of an arbitrary initial segmentation are tested for uniformity and if not uniform they are subdivided into smaller regions, or set aside if their size is below a given threshold. Next regions classified as uniform are subject to a cluster analysis to identify similar types which are merged. At this point there exist reliable estimates of the parameters of the random field of each type of region and they are used to classify some of the remaining small regions. Any regions remaining after this step are considered part of a boundary ambiguity zone. The location of the boundary is estimated then by interpolation between the existing uniform regions. Experimental results on artificial pictures are also included.     

利用视觉显著性的图像分割方法

提出一种利用视觉显著性对图像进行分割的方法。首先提取图像的底层视觉特征,从局部显著性、全局显著性和稀少性3个方面计算各特征图像中各像素的视觉显著性,得到各特征显著图;对各特征显著图进行综合,生成最终的综合显著图。然后对综合显著图进行阈值分割,得到二值图像,将二值图像与原始图像叠加,将前景和背景分离,得到图像分割结果。在多幅自然图像上进行实验验证,并给出相应的实验结果和分析。实验结果表明,该方法正确有效,具有和人类视觉特性相符合的分割效果。     

基于图像显著性检测的图像分割

图像分割在许多图像处理和机器视觉问题中是一个非常重要的过程,是将一幅图分割成几个显著的区域,然而不能将其中最显著的目标直接分割出来,需要进一步处理。为此本文采用显著性检测的算法实现了对目标的分割。显著性区域检测可以应用于目标检测、图像检索、图像分割等机器视觉问题。使用杨等人提出的基于图论的流形排序算法检测显著性算法得到显著性图,再结合mean-shift分割算法,实现了对视觉显著性目标分割提取,可获得可观的图像分割结果,并将此算法应用到了森林火灾检测中,能对图像中的火焰部分进行有效的分割提取。     

图像分割技术分析与展望

图像分割是图像处理中的一项关键技术,也是一经典难题,文章对近几年来出现的图像分割方法作了较为全面的分析,并对图像分割技术的研究方向作了探讨,对从事图像处理学习与研究的人员具有一定的启发作用。     

无需初始轮廓的图像分割模型

为了增强对初始轮廓的鲁棒性并提高对灰度不均图像、噪声图像的分割效率,提出一种基于区域的活动轮廓模型.首先分别构造全局灰度拟合力与局部灰度拟合力,然后用线性组合获得模型的拟合项,并通过调整拟合力之间的权重提高模型对初始轮廓的鲁棒性,最后利用演化曲线的长度项保持曲线的光滑性.通过实验结果可以看出:与区域可变灰度拟合(RSF...     

Automated segmentation of brain MR images

A simple, robust and efficient image segmentation algorithm for classifying brain tissues from dual echo Magnetic Resonance (MR) images is presented. The algorithm consists of a sequence of adaptive histogram analysis, morphological operations and knowledge based rules to accurately classify various regions such as the brain matter and the cerebrospinal fluid, and detect if there are any abnormal regions. It can be completely automated and has been tested on over hundred images from several patient studies. Experimental results are provided.