一种改进的基于MST的聚类算法

聚类是将数据分类到不同的类的一个过程,使同一个类中的对象有较大的相似性,不同类的个体有较大的差异性。本文提出一种改进的基于MST的聚类算法。该算法能更准确地确定不一致边,较好地符合人类视觉感知过程;聚类有效性表明该算法可提高聚类的效果;在信息分类与识别方面具有一定的应用价值。     

一种融合聚类与区域生长的彩色图像分割方法

论文提出了一种将聚类和区域生长有机融合的彩色图像分割方法。为了捕获图像的纹理特征,首先将图像划分成16×16子块,然后在块中按照视觉一致性准则进行颜色聚类,对于聚类后的子块,提取其颜色与纹理特征,然后采用符合人类视觉特征的生长规则,进行基于子块的区域生长。该方法充分利用了聚类算法和区域生长算法的各自优点,并符合人类视觉特征的分割策略。利用提出的算法对多幅自然图像进行了分割实验,实验结果证明了算法的有效性。     

自适应模糊C均值聚类彩色图像分割方法

模糊C均值聚类用于彩色图像分割具有简单直观,易于实现的特点,但存在聚类性能受中心点初始化影响且计算量大等问题,为此,提出一种自适应模糊C均值分割方法.算法根据人类的视觉特性,参照NBS距离与人类视觉对颜色差别的定量关系,结合具体图像的色彩分布,自动确定初始聚类中心及聚类数目,继而进行模糊C均值聚类.实验表明,该方法无需人为的干预,分割速度快,分割效果跟人的主观视觉感知保持了良好的一致性.     

基于模糊C均值聚类的环境感知推荐算法

针对现有环境感知推荐算法存在的不足,提出一种基于模糊C均值聚类的环境感知推荐算法.首先采用模糊C均值聚类算法对历史环境信息进行聚类,产生聚类及隶属矩阵;然后匹配活动用户环境信息与历史环境信息聚类,采用聚类隶属度作为映射系数将符合条件的非隶属数据映射为隶属数据,最终选择与活动环境匹配的隶属用户评分数据为用户产生推荐.同现有算法相比,该算法不仅解决了因用户环境改变不能准确推荐项目的问题,而且通过采用模糊聚类算法克服了传统硬聚类问题,并且借助于隶属映射函数解决了聚类产生的数据稀疏性问题.在MovieLens数据集上比较了新算法和其他算法的性能,验证了所提算法的有效性.     

SROC:一种面向结构鲁棒性的迭代聚类方法

聚类结果的有效性由结构有效性、算法有效性和先验知识有效性3个方面的因素决定.忽略先验知识和假设结构的有效性孤立地提升聚类算法的有效性很可能产生无效的聚类结果.现有聚类方法通常只是简单地导出假设结构下最优的聚类结果,并交付用户,缺乏对聚类结果的自省能力.实际上,聚类方法是一个不断迭代优化的过程,包括对训练数据拟合度和假设结构的迭代优化.基于上述的考虑,提出以聚类结构的鲁棒性作为聚类结果有效性的衡量指标,并将鲁棒性评估有机地整合到聚类算法的迭代优化过程中,提出一种面向结构鲁棒性的迭代聚类方法框架.此外,依托该框架下设计并实现了SROC聚类算法,通过对模拟数据和真实文档数据的聚类实验,例证了方法有效性.     

面向结构稳定性的分裂-合并聚类算法

聚类是在假设数据具有某种群聚结构的前提下根据观察到的无标记样本发现数据的最优划分。现有的聚类算法通常简单地导出假设结构和给定先验下最优或较优的聚类结果,体现为算法对样本分布拟合度的迭代最优化,即算法有效性。实际上,聚类的有效性取决于结构有效性、算法有效性和先验有效性3个方面的因素。基于这种考虑,提出了一种变体混合模型的聚类结构假设,以及判定聚类结构的稳定性的度量和方法,在算法有效的前提下通过单簇的分裂与合并来改进聚类结构的稳定性,并得到最终聚类结果,设计并实现了SMClus聚类算法,通过对模拟数据和真实数据的聚类实验,例证了方法的有效性。     

基于灰色聚类的图像检索技术

受现有灰色系统研究成果的启发，将灰色聚类方法应用于CBIR的研究巾，建立了CBIR与灰色聚类的对应哭系，提出了一种全新的基于灰色聚类的图像检索技术。该方法首先对用户主观性相似判断进行定性分析，确定若干个灰类；然后采用相应的训练算法建立各个灰类的白化函数；最后，采用灰色聚类方法对数据库图像进行聚类分析，得到检索结果集。这种方法既考虑了人类视觉感知的特点，同时又简化了问题的复杂度，从而使图像检索的效率与性能得以同时提高。     

不完全K-means聚类与分类优化结合的图像分割算法

为提升K均值聚类的效率及图像分割效果,提出了一种不完全K均值聚类与分类优化结合的图像分割(IKCO)算法。首先,采用简单的方法来进行数据精简及初始中心的确定;然后,根据给出的不完全聚类准则对图像进行聚类分割;最后,对分割结果进行分类优化以提升分割效果。实验结果表明,相对于传统的K均值聚类方法,IKCO算法在进行图像分割时具有很好的分割效率,且分割效果与人类视觉感知具有更高的一致性。     

基于K-means聚类的数字半色调算法

数字半色调是在二值设备或多色二值设备上实现图像再现的一门技术,提出将K-means聚类法应用在数字半色调技术中。算法中应用人类视觉系统模型(HVS)和印刷模型最大限度减少原始灰度连续调图像和半色调图像之间的视觉误差;利用K-means聚类法将灰度图像划分成聚类分区,在每个聚类分区应用最小平方法(least-squares)最小化二值半色调图像和原始灰度级图像之间的平方误差,所构造的半色调算法与基于模型的最小平方法(LSMB)算法相比,随着聚类分区的增加,图像平滑且边缘清晰度增加,尤其是在图像细节部位。与LSMB算法比较,该算法的均方误差值有所降低,而权重信噪比和峰值信噪比提高了0.2～2 dB,模拟实验结果验证了算法的有效性。     

利用CUDA提高内存数据聚类效能的研究

提出一种新的聚类算法AIK-Means,利用CUDA技术加速算法执行效率,并优化内存方法,可在有限时间内进行多次聚类;将Chameleon层次聚类算法用于解决K-Means算法的初始聚类中心敏感问题;在多次聚类结果中用FP-Tree进行关联分析,提高聚类有效性。将算法应用到某集团心理学MMPI数据测试,实验结果表明AIK-Means算法在执行效率和聚类有效性上具有良好的效果。     

Clustering by scale-space filtering

In pattern recognition and image processing, the major application areas of cluster analysis, human eyes seem to possess a singular aptitude to group objects and find important structures in an efficient and effective way. Thus, a clustering algorithm simulating a visual system may solve some basic problems in these areas of research. From this point of view, we propose a new approach to data clustering by modeling the blurring effect of lateral retinal interconnections based on scale space theory. In this approach, a data set is considered as an image with each light point located at a datum position. As we blur this image, smaller light blobs merge into larger ones until the whole image becomes one light blob at a low enough level of resolution. By identifying each blob with a cluster, the blurring process generates a family of clustering along the hierarchy. The advantages of the proposed approach are: 1) The derived algorithms are computationally stable and insensitive to initialization and they are totally free from solving difficult global optimization problems. 2) It facilitates the construction of new checks on cluster validity and provides the final clustering a significant degree of robustness to noise in data and change in scale. 3) It is more robust in cases where hyperellipsoidal partitions may not be assumed. 4) it is suitable for the task of preserving the structure and integrity of the outliers in the clustering process. 5) The clustering is highly consistent with that perceived by human eyes. 6) The new approach provides a unified framework for scale-related clustering algorithms derived from many different fields such as estimation theory, recurrent signal processing on self-organization feature maps, information theory and statistical mechanics, and radial basis function neural networks     

On mean shift-based clustering for circular data

Cluster analysis is a useful tool for data analysis. Clustering methods are used to partition a data set into clusters such that the data points in the same cluster are the most similar to each other and the data points in the different clusters are the most dissimilar. The mean shift was originally used as a kernel-type weighted mean procedure that had been proposed as a clustering algorithm. However, most mean shift-based clustering (MSBC) algorithms are used for numeric data. The circular data that are the directional data on the plane have been widely used in data analysis. In this paper, we propose a MSBC algorithm for circular data. Three types of mean shift implementation procedures with nonblurring, blurring and general methods are furthermore compared in which the blurring mean shift procedure is the best and recommended. The proposed MSBC for circular data is not necessary to give the number of cluster. It can automatically find a final cluster number with good clustering centers. Several numerical examples and comparisons with some existing clustering methods are used to demonstrate its effectiveness and superiority of the proposed method.     

复杂高维数据的密度峰值快速搜索聚类算法

机器学习的无监督聚类算法已被广泛应用于各种目标识别任务。基于密度峰值的快速搜索聚类算法(DPC)能快速有效地确定聚类中心点和类个数,但在处理复杂分布形状的数据和高维图像数据时仍存在聚类中心点不容易确定、类数偏少等问题。为了提高其处理复杂高维数据的鲁棒性,文中提出了一种基于学习特征表示的密度峰值快速搜索聚类算法(AE-MDPC)。该算法采用无监督的自动编码器(AutoEncoder)学出数据的最优特征表示,结合能刻画数据全局一致性的流形相似性,提高了同类数据间的紧致性和不同类数据间的分离性,促使潜在类中心点的密度值成为局部最大。在4个人工数据集和4个真实图像数据集上将AE-MDPC与经典的K-means,DBSCAN,DPC算法以及结合了PCA的DPC算法进行比较。实验结果表明,在外部评价指标聚类精度、内部评价指标调整互信息和调整兰德指数上,AE-MDPC的聚类性能优于对比算法,而且提供了更好的可视化性能。总之,基于特征表示学习且结合流形距离的AE-MDPC算法能有效地处理复杂流形数据和高维图像数据。     

一种基于视觉感知的非线性幅型比变换方法

随着高清电视的出现,幅型比变换的应用范围越来越广泛。本文提出了一种基于人的视觉感知特性的非线性幅型比变换方法。该方法利用运动估计技术获得视频帧的运动矢量,采用基于修正划分模糊度的模糊聚类算法对运动矢量进行聚类并估算每一帧的运动重心(MCOG)。同时针对幅型比变换后由视频序列前后帧不连续引起的视觉上的抖动现象,采用基于运动重心和中心区域的非均匀区域划分法,并针对不同的区域进行非线性比率扩展。实验结果表明,该方法很好地反映了人的视觉对视频的感知情况,变换后的视觉效果明显优于传统的幅型比变换方法。     

A semi-supervised probabilistic model for clustering large databases of complex images

Image content clustering is an effective way to organize large databases thereby making the content based image retrieval process much easier. However, clustering of images with varied background and foreground is quite challenging. In this paper, we propose a novel image content clustering paradigm suitable for clustering large and diverse image databases. In our approach images are represented in a continuous domain based on a probabilistic Gaussian Mixture Model (GMM) with the images modeled as mixture of Gaussian distributions in the selected feature space. The distance metric between the Gaussian distributions is defined in the sense of Kullback–Leibler (KL) divergence. The clustering is done using a semi-supervised learning framework where labeled data in the form of cluster templates is used to classify the unlabelled data. The clusters are formed around initially chosen seeds and are updated in the due course based on user inputs. In our clustering approach the user interaction is done in a structured way as to get maximum inputs from the user in a limited time. We propose two methods to carry out the structured user interaction using which the cluster templates are updated to improve the quality of the clusters formed. The proposed method is experimentally evaluated on benchmark datasets that are specifically chosen to include a wide variation of images around a common theme that is typically encountered in applications like photo-summarization and poses a major semantic gap challenge to conventional clustering approaches. The experimental results presented demonstrate the effectiveness of the proposed approach.     

快速模糊C均值聚类彩色图像分割方法

模糊C均值(FCM)聚类用于彩色图像分割具有简单直观、易于实现的特点，但存在聚类性能受中心点初始化影响且计算量大等问题，为此，提出了一种快速模糊聚类方法(FFCM)。这种方法利用分层减法聚类把图像数据分成一定数量的色彩相近的子集，一方面，子集中心用于初始化聚类中心点；另一方面，利用子集中心点和分布密度进行模糊聚类，由于聚类样本数量显著减少以及分层减法聚类计算量小，故可以大幅提高模糊C均值算法的计算速度，进而可以利用聚类有效性分析指标快速确定聚类数目。实验表明，这种方法不需事先确定聚类数目并且在优化聚类性能不变的前提下，可以使模糊聚类的速度得到明显提高，实现彩色图像的快速分割。     

Multispectral remote sensing image segmentation using rival penalized controlled competitive learning and fuzzy entropy

This paper proposes an image segmentation approach for multispectral remote sensing imagery based on rival penalized controlled competitive learning (RPCCL) and fuzzy entropy. In this approach, the clustering center component for each band of the image is first chosen based on the fuzzy entropy histogram of the corresponding band of the image. The initial clustering centers are then formed by combining the obtained clustering center components. The number of clusters and the real clustering centers are then determined by the use of the RPCCL method. The advantages of the proposed approach are the appropriate initial cluster centers and the fact that the number of clusters is determined automatically. The results of the experiments showed that without providing the number of clustering centers before the clustering operation, the proposed method can effectively perform an unsupervised segmentation of remote sensing images.     

一种快速的模糊C均值聚类彩色图像分割方法

FCM用于彩色图像分割存在聚类数目需要事先确定、计算速度慢的问题,为此,提出一种快速的模糊C均值聚类方法（FFCM）。首先,对原始彩色图像进行基于梯度图的分水岭变换,从而把原始彩色图像数据分成一些具有色彩一致性的子集;然后,利用这些子集的大小和中心点进行模糊聚类。由于FFCM聚类样本数量显著减小,因此可以大幅提高模糊C均值聚类算法的计算速度,进而可以采用聚类有效性指标确定聚类数目。实验表明,这种方法不需要事先确定聚类数目,在聚类有效性能不变的前提下,可以使模糊聚类的速度得到明显提高,实现了彩色图像的快速分割。     

A robust dynamic niching genetic algorithm with niche migration for automatic clustering problem

In this paper, a genetic clustering algorithm based on dynamic niching with niche migration (DNNM-clustering) is proposed. It is an effective and robust approach to clustering on the basis of a similarity function relating to the approximate density shape estimation. In the new algorithm, a dynamic identification of the niches with niche migration is performed at each generation to automatically evolve the optimal number of clusters as well as the cluster centers of the data set without invoking cluster validity functions. The niches can move slowly under the migration operator which makes the dynamic niching method independent of the radius of the niches. Compared to other existing methods, the proposed clustering method exhibits the following robust characteristics: (1) robust to the initialization, (2) robust to clusters volumes (ability to detect different volumes of clusters), and (3) robust to noise. Moreover, it is free of the radius of the niches and does not need to pre-specify the number of clusters. Several data sets with widely varying characteristics are used to demonstrate its superiority. An application of the DNNM-clustering algorithm in unsupervised classification of the multispectral remote sensing image is also provided.