Block address predictive colour quantisation image compression

To display a decompressed colour image of the conventional DCT-based compression algorithms on a palette-based display system, the decoded image must be colour quantised. To avoid the computing-intensive colour quantisation process and provide a fast decoding process, a new block address predictive colour quantisation image compression scheme is proposed. A closest-pairs colour palette ordering technique is also proposed for effectively exploiting the redundancy of the palettised image.<>     

A Scalable Framework For Segmenting Magnetic Resonance Images

A fast, accurate and fully automatic method of segmenting magnetic resonance images of the human brain is introduced. The approach scales well allowing fast segmentations of fine resolution images. The approach is based on modifications of the soft clustering algorithm, fuzzy c-means, that enable it to scale to large data sets. Two types of modifications to create incremental versions of fuzzy c-means are discussed. They are much faster when compared to fuzzy c-means for medium to extremely large data sets because they work on successive subsets of the data. They are comparable in quality to application of fuzzy c-means to all of the data. The clustering algorithms coupled with inhomogeneity correction and smoothing are used to create a framework for automatically segmenting magnetic resonance images of the human brain. The framework is applied to a set of normal human brain volumes acquired from different magnetic resonance scanners using different head coils, acquisition parameters and field strengths. Results are compared to those from two widely used magnetic resonance image segmentation programs, Statistical Parametric Mapping and the FMRIB Software Library (FSL). The results are comparable to FSL while providing significant speed-up and better scalability to larger volumes of data.     

融入局部信息的直觉模糊核聚类图像分割算法

针对传统直觉模糊C均值聚类(Intuitionistic Fuzzy C-means,IFCM)的图像分割算法对噪声和初始聚类中心敏感,导致聚类精度不高和迭代次数多的问题,提出一种结合局部信息的直觉模糊核聚类的图像分割算法。在该算法中,首先采用基于直方图的方法确定聚类中心初始值,解决算法对聚类中心的初始值敏感的问题;其次,利用核函数将待分类数据集映射到高维非线性空间,改善分类数据的线性可分性,同时在目标函数中引入局部灰度信息和局部空间信息,优化直觉模糊隶属度的计算方法,提高直觉模糊聚类的分类精度。实验结果表明,提出算法能减少迭代次数,提高聚类精度,能有效对图像进行分割;无论在对图像分割还是在聚类有效性上,提出算法都要优于传统的模糊聚类算法,如模糊C均值聚类(Fuzzy C-means,FCM)、模糊核均值聚类(Kernel-based fuzzy c-means,KFCM)）、引入空间信息的直觉模糊C均值聚类(Intuitionistic Fuzzy C-means with spatial constraints ,IFCM-S)、模糊空间聚类(Fuzzy Local Information C-means,FLICM）、直觉模糊C均值聚类(Intuitionistic Kernel-based Fuzzy C-means,IFKCM）等。      

Joint quantisation and error diffusion of colour images usingcompetitive learning

A competitive learning scheme for colour image quantisation is elaborated, in which the dithering process to eliminate contouring effects is embedded in the quantisation process instead of performed a posteriori. Quantisation is performed by clustering in colour space. The dithering process is a simple error diffusion, in which the quantisation error made by one pixel is diffused to its local neighbourhood. An objective function which takes the dithering process into account is optimised by use of a competitive learning approach. In this way, the colour quantisation process is optimally adapted to the dithered image, and the dithering process is optimally adapted to the colour palette. For small colour palettes, this is demonstrated to improve the visual quality of quantised images     

A multiresolution image segmentation technique based on pyramidalsegmentation and fuzzy clustering

In this paper, an unsupervised image segmentation technique is presented, which combines pyramidal image segmentation with the fuzzy c-means clustering algorithm. Each layer of the pyramid is split into a number of regions by a root labeling technique, and then fuzzy c-means is used to merge the regions of the layer with the highest image resolution. A cluster validity functional is used to find the optimal number of objects automatically. Segmentation of a number of synthetic as well as clinical images is illustrated and two fully automatic segmentation approaches are evaluated, which determine the left ventricular volume (LV) in 140 cardiovascular magnetic resonance (MR) images. First fuzzy c-means is applied without pyramids. In the second approach the regions generated by pyramidal segmentation are merged by fuzzy c-means. The correlation coefficients of manually and automatically defined LV lumen of all 140 and 20 end-diastolic images were equal to 0.86 and 0.79, respectively, when images were segmented with fuzzy c-means alone. These coefficients increased to 0.90 and 0.93 when the pyramidal segmentation was combined with fuzzy c-means. This method can be applied to any dimensional representation and at any resolution level of an image series. The evaluation study shows good performance in detecting LV lumen in MR images.     

Infrared image segmentation algorithm based on distribution information intuitionistic fuzzy c-means clustering

Due to the sensitivity of the traditional intuitionistic fuzzy c-means (IFCM) clustering algorithm to the clustering center in image segmentation,which resulted in the low clustering precision,poor retention of details,and large time complexity,an intuitionistic fuzzy c-means clustering algorithm was proposed based on spatial distribution information suitable for infrared image segmentation of power equipment.The non-target objects with high intensity and the non-uniformity of image intensity in the infrared image had strong interference to the image segmentation,which could be effectively suppressed by the proposed algorithm.Firstly,the Gaussian model was introduced into the global spatial distribution information of power equipment to improve the IFCM algorithm.Secondly,the membership function was optimized by local spatial operator to solve the problem of edge blur and image intensity inhomogeneity.The experiments conducted on Terravic motion IR database and the data set containing 300 infrared images of power equipment show that,the relative region error rate is about 10% and is less affected by the change of fuzzy factor m.The effectiveness and applicability of the proposed algorithm are superior to other comparison algorithms.     

基于模糊C均值聚类与空间信息相结合的图像分割新算法

针对传统的模糊C均值聚类（FCM）图像分割方法未考虑图像的空间信息,对噪声十分敏感的问题,本文提出了一种结合空间信息的模糊C均值聚类分割新算法;该算法将图像的二维直方图引入传统的模糊C均值聚类算法中,并对隶属函数做了改进;依据平方误差和最小准则,来确定模糊分类矩阵及聚类中心;最后,依据最大隶属度原则,划分图像像素的类别归属,以改善传统的PCM算法的分割质量。实验结果表明,该算法显示了较好的分割效果和较强的抗噪性能。     

基于模糊聚类的图像分割研究进展

模糊聚类算法（Fuzzy C-Means,FCM）是一种基于软划分的聚类过程,已被广泛应用于机器学习、图像处理和计算机视觉等领域.虽然当前已涌现出大量关于FCM的图像分割算法,但仍然面临诸多挑战.本文将基于FCM的图像分割算法归纳为三类：基于空间邻域信息的FCM算法、基于直方图信息的快速FCM算法及基于维度加权的FCM算法.首先系统分析和阐述了各类FCM算法的研究现状,然后通过实验分析各类算法的性能,最后总结了FCM算法在图像分割中存在的问题以及将来的研究方向.     

Fuzzy image clustering incorporating spatial continuity

The authors present a spatial fuzzy clustering algorithm that exploits the spatial contextual information in image data. The objective functional of their method utilises a new dissimilarity index that takes into account the influence of the neighbouring pixels on the centre pixel in a 3×1 window. The algorithm is adaptive to the image content in the sense that influence from the neighbouring pixels is suppressed in nonhomogeneous regions in the image. A cluster merging scheme that merges two clusters based on their closeness and their degree of overlap is presented. Through this merging scheme, an `optimal' number of clusters can be determined automatically as iteration proceeds. Experimental results with synthetic and real images indicate that the proposed algorithm is more tolerant to noise, better at resolving classification ambiguity and coping with different cluster shape and size than the conventional fuzzy c-means algorithm     

Visual privacy-preserving level evaluation for multilayer compressed sensing model using contrast and salient structural features

Recognition and classification tasks in images or videos are ubiquitous, but they can lead to privacy issues. People increasingly hope that camera systems can record and recognize important events and objects, such as real-time recording of traffic conditions and accident scenes, elderly fall detection, and in-home monitoring. However, people also want to ensure these activities do not violate the privacy of users or others. The sparse representation classification and recognition algorithms based on compressed sensing (CS) are robust at recognizing human faces from frontal views with varying expressions and illuminations, as well as occlusions and disguises. This is a potential way to perform recognition tasks while preserving visual privacy. In this paper, an improved Gaussian random measurement matrix is adopted in the proposed multilayer CS (MCS) model to realize multiple image CS and achieve a balance between visual privacy-preserving and recognition tasks. The visual privacy-preserving level evaluation for MCS images has important guiding significance for image processing and recognition. Therefore, we propose an image visual privacy-preserving level evaluation method for the MCS model (MCS-VPLE) based on contrast and salient structural features. The basic concept is to use the contrast measurement model based on the statistical mean of the asymmetric alpha-trimmed filter and the salient generalized center-symmetric local binary pattern operator to extract contrast and salient structural features, respectively. The features are fed into a support vector regression to obtain the image quality score, and the fuzzy c-means algorithm is used for clustering to obtain the final evaluated image visual privacy-preserving score. Experiments on three constructed databases show that the proposed method has better prediction effectiveness and performance than conventional methods.     

基于核距离的直觉模糊c均值聚类算法

针对现有直觉模糊c均值聚类算法无法发现非凸聚类结构的缺陷,提出了一种基于核化距离的直觉模糊c均值聚类算法。算法在定义了基于核的直觉模糊欧式距离基础上,通过把聚类样本映射到高维特征空间,使原来没有显现的特征突现出来,从而能够更好地聚类。实验选择一组人工数据集及一组UCI数据集测试了本文算法,并将其与五种经典的聚类算法进行了比较。实验结果充分表明了该算法的有效性及优越性。     

A New Method for the Estimation of Mass Functions in?the?Dempster�CShafer��s Evidence Theory: Application to Colour Image Segmentation

In this paper, the problem of colour image segmentation is addressed using the Dempster–Shafer (DS) theory. Examples are provided showing that this theory is able to take into account a large variety of special situations that occur and which are not well solved using classical approaches. Modelling both uncertainty and imprecision, and computing the conflict between images and introducing a priori information are the main features of this theory. Consequently, the performance of such a segmentation scheme is largely conditioned by the appropriate estimation of mass functions in the DS evidence theory. In this paper, a new method of automatically determining the mass function for colour-image segmentation problems is presented. The mass function of each pixel is determined by applying possibilistic c-means (PCM) clustering to the grey levels of the three primitive colours. A reliability criterion, associated with each pixel and the mass functions of its neighbouring pixels, is used into a fuzzy based reasoning system in order to decide on the appropriate segmentation. Experimental segmentation results on medical and textured colour images highlight the effectiveness of the proposed method.     

Comparison of Clustering Methods in Yeast Saccharomyces Cerevisiae

In recent years,microarray technology has been widely applied in biological and clinical studies for simultaneous monitoring of gene expression in thousands of genes.Gene clustering analysis is found useful for discovering groups of correlated genes potentially co-regulated or associated to the disease or conditions under investigation.Many clustering methods including k-means,fuzzy c-means,and hierarchical clustering have been widely used in literatures.Yet no comprehensive comparative study has been performed to evaluate the effectiveness of these methods,specially,in yeast saccharomyces cerevislae.In this paper,these three gene clustering methods are compared.Classification accuracy and CPU time cost are employed for measuring performance of these algorithms.Our results show that hierarchical clustering outperforms k-means and fuzzy c-means clustering.The analysis provides deep insight to the complicated gene clustering problem of expression profile and serves as a practical guideline for routine microarray cluster analysis of gene expression.     

Fuzzy C-means Clustering Image Segmentation Algorithm Based on Hidden Markov Model

Mobile Networks and Applications - Aiming at the poor anti-jamming effect of traditional fuzzy c-means clustering image segmentation method, a fuzzy c-means clustering image segmentation algorithm...     

基于SPKFCM快速双循环水平集非均匀图像分割

针对传统快速双循环水平集对初始演化曲线过于依赖的问题,提出一种基于空间惩罚核模糊C-means (SPKFCM)算法的初始演化曲线自动选取快速双循环水平集算法.首先,对模糊均值聚类算法进行改进,通过增加空间惩罚函数提出SPKFCM算法,用于对快速双循环水平集算法的自动初始化;其次,基于SPKFCM并结合快速双循环水平集算法,设计基于SPKFCM快速双循环水平集算法框架,并给出相应速度参量Fd和Fint模糊化形式;最后,通过与已有算法在仿真图像上的对比结果显示,所提算法在随机初始化条件下,具有更高的分割精度和计算效率.     

采用NSCT与FCM相结合的SAR和多光谱图像融合算法

合成孔径雷达（SAR）和多光谱（MS）图像的融合,有助于得到对观察对象的更好地视觉感知。但是,由于其内在成像机制上的差异,许多经典的方法已被证明不适合这一研究,因此本文提出了采用非下采样contourlet变换（NSCT）和模糊C均值聚类（FCM）相结合的图像融合算法。采用FCM对SAR图像进行分割,得到目标区域和背景区域;采用NSCT对SAR图像和多光谱图像进行分解,得到低频子带和高频方向子带;对于低频部分,不同分割区域采用不同的自适应融合准则进行融合;对于高频部分,采用区域块能量准则进行融合;最后,通过NSCT逆变换得到融合后图像。实验结果表明,该算法的融合图像能很好的保留SAR图像的目标信息和多光谱图像的光谱信息,融合效果优于大部分传统的融合算法。      

Convergent algorithms for successive approximation vectorquantisation with applications to wavelet image compression

Embedded wavelet coders have become very popular in image compression applications, owing to their simplicity and high coding efficiency. Most of them incorporate some form of successive approximation scalar quantisation. Recently developed algorithms for successive approximation vector quantisation have been shown to be capable of outperforming successive approximation scalar quantisation ones. In the paper, some algorithms for successive approximation vector quantisation are analysed. Results that were previously known only on an experimental basis are derived analytically. An improved algorithm is also developed and is proved to be convergent. These algorithms are applied to the coding of wavelet coefficients of images. Experimental results show that the improved algorithm is more stable in a rate×distortion sense, while maintaining coding performances compatible with the state-of-the-art     

关于FCM算法中的权重指数m的一点注记

模糊c均值算法(FCM)是经常使用的聚类算法之一.使用模糊c均值算法时,如何选取模糊指标m一直是一个悬而未决的问题.部分文献根据实验结果建议最佳的权重指数可能位于区间 ,但大多数研究者使用m=2.本文阐述了FCM算法有效性与聚类有效性之间的理论联系,指出如果某个权重指数使得FCM算法作为聚类算法不能有效工作,则其不能作为最佳的权重指数.据此,我们进行了数据实验,数据实验结果说明了权重指数的最佳取值未必位于区间 .     

Grey relational analysis based approach for data clustering

This paper generalises the concept of grey relational analysis to develop a technique, called grey relational pattern analysis, for analysing the similarity between given patterns. Based on this technique, a clustering algorithm is proposed for finding cluster centres of a given data set. This approach can be categorised as an unsupervised clustering algorithm because it does not need predetermination of appropriate cluster centres in the initialisation. The problem of determining the optimal number of clusters and optimal locations of cluster centres is also considered. Finally, the approach is used to solve several data clustering problems as examples. In each example, the performance of the proposed algorithm is compared with other well-known algorithms such as the fuzzy c-means method and the hard c-means method. Simulation results demonstrate the effectiveness and feasibility of the proposed method.     

A novel fuzzy clustering algorithm with non local adaptive spatial constraint for image segmentation

Generalized fuzzy c-means clustering algorithm with improved fuzzy partitions (GIFP_FCM) is a novel fuzzy clustering algorithm. However when GIFP_FCM is applied to image segmentation, it is sensitive to noise in the image because of ignoring the spatial information contained in the pixels. In order to solve this problem, a novel fuzzy clustering algorithm with non local adaptive spatial constraint (FCA_NLASC) is proposed in this paper. In the proposed method, a novel non local adaptive spatial constraint term is introduced to modify the objective function of GIFP_FCM. The characteristic of this technique is that the adaptive spatial parameter for each pixel is designed to make the non local spatial information of each pixel playing a different role in guiding the noisy image segmentation. Segmentation experiments on synthetic and real images, especially magnetic resonance (MR) images, are performed to assess the performance of an FCA_NLASC in comparison with GIFP_FCM and fuzzy c-means clustering algorithms with local spatial constraint. Experimental results show that the proposed method is robust to noise in the image and more effective than the comparative algorithms.