基于人工蜂群与模糊C均值的自适应小波变换的噪声图像分割

针对传统模糊C均值（FCM）聚类算法在处理噪声图像时易受到噪声影响的问题,提出了基于FCM的小波域特征增强的噪声图像分割方法。首先,将噪声图像进行二维小波分解;其次,对近似系数进行边缘增强,同时利用人工蜂群（ABC）优化算法对细节系数进行阈值处理,并将处理后的系数进行小波重构;最后,对重构后的图片使用FCM算法来进行图像分割。选取5幅典型的灰度图像,分别添加高斯噪声和椒盐噪声,使用多种方法进行分割,以分割后图像的峰值信噪比（PSNR）和误分率（ME）作为性能指标,实验结果表明,所提方法分割后的图片相较于传统FCM聚类算法分割方法和粒子群优化（PSO）分割方法分割后的图片在PSNR上最多分别有281%和54%的提升,在ME上最多分别有55%和41%的降低。可见所提出的分割方法较好地保留了图像边缘纹理信息,其抗噪性能与分割性能得到了提升。     

Typhoon cloud image enhancement and reducing speckle with genetic algorithm in stationary wavelet domain

By employing discrete stationary wavelet transform (SWT), generalised cross-validation (GCV), genetic algorithm (GA), and non-linear gain operator, an efficient de-noising and enhancement algorithm for typhoon cloud image is proposed. Having implemented SWT to a typhoon cloud image, noise in a typhoon cloud image is reduced by modifying the stationary wavelet coefficients using GA and GCV at fine resolution levels. Asymptotical optimal de-noising threshold can be obtained, without knowing the variance of noise, by only employing the known input image data. GA and non-linear gain operator are used to modify the stationary wavelet coefficients at coarse resolution levels in order to enhance the details of a typhoon cloud image. Experimental results show that the proposed algorithm can efficiently reduce the speckle in a typhoon cloud image while well enhancing the detail. In order to accurately assess an enhanced typhoon cloud image's quality, an overall score index is proposed based on information entropy, contrast measure and peak signal-noise-ratio (PSNR). Finally, comparisons between the proposed algorithm and other similar methods, which are proposed based on discrete wavelet transform, are carried out.     

Adaptive typhoon cloud image enhancement using genetic algorithm and non-linear gain operation in undecimated wavelet domain

By combining discrete undecimated wavelet transform (UWT) with genetic algorithm (GA) an efficient enhancement algorithm for typhoon cloud image is proposed. Having implemented UWT to a typhoon cloud mage, noise in a typhoon cloud image is reduced by modifying the undecimated wavelet coefficients by combining with generalization cross validation at fine resolution levels. GA and non-linear gain operation are used to modify the undecimated wavelet coefficients at coarse resolution levels in order to extrude the details of a typhoon cloud image. Experimental results show that the proposed algorithm can efficiently reduce the additive gauss white noise in a typhoon cloud image while well extruding the detail. In order to accurately assess an enhanced typhoon cloud image’s quality, an overall score index is proposed based on information entropy, contrast measure and peak signal-noise ratio. Finally, comparisons between the proposed algorithm and five other similar methods, are carried out.     

台风云图伪彩色增强的Berkeley小波变换法

将Berkeley小波变换(BWT)和线性分配伪彩色增强方法相结合,给出一种有效的台风云图伪彩色增强方法。首先在Berkeley小波域增强云图的细节,然后将增强后的云图分别利用经典的线性分配和改进的线性分配法进行彩色增强。最后将所给出的方法与直接利用经典的线性分配方法、经典离散正交小波预处理后利用改进的线性分配方法进行对比分析。实验结果证明,该方法简便易行,运算量小,在应用中有较大的灵活性,为低对比度台风云图增强处理提供了一种新途径,同时能够有效突出台风眼区和外围螺旋云带等台风结构信息,为后续台风中心定位和台风强度预报提供参考。     

基于云模型的彩色图像分割方法

以云模型理论为基础分析彩色图像分割概念,研究已有的彩色图像分割方法,并与云模型相结合,提出基于云模型的彩色图像分割方法。该方法在HSV颜色空间对彩色图像进行非均匀量化,并寻找量化后图像的基本直方图,最后通过云模型的“3En规则”对图像进行前景/背景分割。通过与K均值算法、IS-RSC算法进行比较,实验结果表明了该方法对彩色图像分割的有效性。     

Combining stationary wavelet transform and self-organizing maps for brain MR image segmentation

This study presents an image segmentation system that automatically segments and labels T1-weighted brain magnetic resonance (MR) images. The method is based on a combination of unsupervised learning algorithm of the self-organizing maps (SOM) and supervised learning vector quantization (LVQ) methods. Stationary wavelet transform (SWT) is applied to the images to obtain multiresolution information for distinguishing different tissues. Statistical information of the different tissues is extracted by applying spatial filtering to the coefficients of SWT. A multidimensional feature vector is formed by combining SWT coefficients and their statistical features. This feature vector is used as input to the SOM. SOM is used to segment images in a competitive unsupervised approach and an LVQ system is used for fine-tuning. Results are evaluated using Tanimoto similarity index and are compared with manually segmented images. Quantitative comparisons of our system with the other methods on real brain MR images using Tanimoto similarity index demonstrate that our system shows better segmentation performance for the gray matter while it gives average results for white matter.     

Connectivity-based local adaptive thresholding for carotid artery segmentation using MRA images

The computer algorithms for the delineation of anatomical structures and other regions of interest on the medical imagery are important component in assisting and automating specific radiological tasks. In addition, the segmentation of region is an important first step for variety image related application and visualization tasks. In this paper, we propose a fast and automated connectivity-based local adaptive thresholding (CLAT) algorithm to segment the carotid artery in sequence medical imagery. This algorithm provides the new feature that is the circumscribed quadrangle on the segmented carotid artery for region-of-interest (ROI) determination. By using the preserved connectivity between consecutive slice images, the size of the ROI is adjusted like a moving window according to the segmentation result of previous slice image. The histogram is prepared for each ROI and then smoothed by local averaging for the threshold selection. The threshold value for carotid artery segmentation is locally selected on each slice image and is adaptively determined through the sequence image. In terms of automated features and computing time, this algorithm is more effective than region growing and deformable model approaches. This algorithm is also applicable to segment the cylinder shape structures and tree-like blood vessels such as renal artery and coronary artery in the medical imagery. Experiments have been conducted on synthesized images, phantom and clinical data sets with various Gaussian noise.     

卫星云图感兴趣区域自动提取方法研究

卫星云图中人们感兴趣的区域(ROI)往往是各类云团,针对卫星云图内容的复杂性,利用直方图模糊加权C均值聚类方法实现云图的图像分割,对分割结果进行后处理,最终获取云图内的感兴趣区域。常规聚类方法需要人工指定类个数,影响了ROI提取过程的自动化程度。引入修正聚类评价指标,基于该指标实现最佳类别个数的自动确定。云图分割是感兴趣区域提取过程的关键,采用的直方图模糊加权C均值聚类方法在原有算法基础上,引入样本权重概念,使得聚类过程更为合理;同时将聚类对象由原始像素转换为灰度直方图,提高了聚类过程执行效率。实验结果表明设计的感兴趣区域提取方法能较为准确地分辨出陆地、水体、低云、中云、卷云、对流云六类区域,提取结果与客观实际一致。     

一种新的灰度直方图分割阈值的自动检测方法

本文提出了一种新的灰度直方图的阈值点自动提取方法。利用灰度直方图的直观特征,把直方图的峰点作为分水岭,每两个相邻的峰值点和两者之间的谷点组成一个水域。从最低的谷点向上升高水位,直到各个水域水满为止。找到水量最大的几个水域,其谷底就是作为分割阈值的谷点。     

Texture segmentation using wavelet transform

Texture analysis such as segmentation and classification plays a vital role in computer vision and pattern recognition and is widely applied to many areas such as industrial automation, bio-medical image processing and remote sensing. This paper describes a novel technique of feature extraction for characterization and segmentation of texture at multiple scales based on block by block comparison of wavelet co-occurrence features. The performance of this segmentation algorithm is superior to traditional single resolution techniques such as texture spectrum, co-occurrences, local linear transforms, etc. The results of the proposed algorithm are found to be satisfactory.     

一种基于小波变换的马尔可夫随机场的视频对象分割

马尔可夫随机场（Markov Random Field,MRF）理论已经被广泛地应用于视频图像的分割。提出一种基于小波变换的马尔可夫随机场模型的视频对象分割算法。该算法利用小波变换将图像序列分解到小波域,并在此基础上建立马尔可夫随机场模型,构造相应的能量函数。通过迭代求解能量函数的最优解,得出标记场,提取出运动对象。仿真结果表明,该算法能够有效地抑制噪声,提高构成对象边界像素的数量,快速有效地提取出视频对象。     

基于小波分析的Mean Shift航拍图像分割算法

对于噪声大、分辨率低的航拍图像,提出了利用小波分析多尺度特性,在较粗尺度下对图像进行分割的算法,可有效抑制Mean Shift图像分割算法的过分割问题。分析了Mean Shift算法中核函数窗宽变化对图像分割结果的影响,提出了改进的误分率表示方法,利用新的图像分割性能指标,对几幅实际的航拍图像进行了定量分析,表明了新算法的优点并说明了误分率性能评价指标的有效性。     

基于自动选取最佳阈值的X光图像快速分割方法*

为实现对数字X光图像进行快速分割,提出一种针对直方图的包络特征进行处理的新方法.该方法采用分水岭算法对数字X光图像的直方图一维信号进行处理.首先计算出图像的直方图,然后对直方图进行形态学滤波,提取出直方图的包络.在此基础上对直方图的包络采用分水岭算法自动提取出最佳阈值.用提取出的阈值进行基于阈值的初步分割,然后进一步采用基于标记的分水岭算法对初步分割的二值图像作进一步分割.通过实验表明,采用该方法可以有效地分割大幅X光图像.     

掌纹ROI分割算法的研究与实现

掌纹感兴趣区(ROI)分割是掌纹识别的关键步骤,目前掌纹分割方法主要存在定位点不易确定和同类图像ROI提取偏移度较大等问题,为改善这些问题,提出一种新的ROI分割算法。首先确定手掌图像中的两个指谷点;然后利用手掌轮廓特定区域边界点拟合直线,以该直线为基准,以固定角度的方式建立直角坐标系,利用指谷点找到掌纹信息丰富的区域,确定掌纹的ROI,最后提取特征矢量进行匹配识别。实验结果表明,该算法分割掌纹ROI的准确度高、速度快,对同类图像分割的偏移度更小,掌纹ROI的提取率达98.2%,掌纹正确识别率提高了3%左右,为基于掌纹的身份认证系统的实现提供了理论和实验依据。     

A novel nonlinear algorithm for typhoon cloud image enhancement

A novel nonlinear gray transform method is proposed to enhance the contrast of a typhoon cloud image. Generally, the typhoon cloud image obtained by a satellite cannot be directly used to make an accurate prediction of the typhoon’s center or intensity because the contrast of the received typhoon cloud image may be bad. Our aim is to extrude the typhoon’s eye in the typhoon cloud image. A normalized arc-tangent transformation operation is designed to enhance global contrast of the typhoon cloud image. Differential evolution algorithm is used to choose the optimal nonlinear transform parameter. Finally, geodesic activity contour model is used to extract the typhoon’s eye to verify the performance of the proposed method. Experimental results show that the proposed method can efficiently enhance the global contrast of the typhoon cloud image while greatly extruding the typhoon’s eye.     

图像分割中算法的应用研究

研究图像优化分割问题,最佳阈值选取直接影响到图像分割的清晰度质量。传统采用经验法进行分割,难以获得最佳阈值,导致分割准确率低,易产生图像误分割。为了提高图象分割准确率,提出一种基于遗传算法的Otsu图像分割。首先对图像进行去噪处理并绘制直方图;然后直方图信息选取适当灰度值作为遗传算法中的初始种群,最优阈值作为目标函数,最后通过选择、交叉和变异等遗传操作得到图像分割最优阈值,并进行图像分割。实验结果表明,遗传算法的Otsu图像分割加快了速度,减少了计算量,提高了图像分割准确率,证明适应于图像实时处理。     

基于图像边缘信息的2维阈值分割方法

为了改善2维阈值分割性能,提高图像分割的效率,在传统2维Otsu阈值分割算法的基础上,提出了一种基于图像边缘信息的2维阈值分割方法。这种改进的方法保留了2维Otsu阈值分割算法分割结果准确的优点,并在此基础上充分利用图像的边缘信息,通过分析图像的边缘直方图和阈值的关系来得到最优分割阈值。仿真实验结果表明,该方法与传统2维分割算法相比,不仅计算简单,而且实时性好。     

基于直方图预处理与BF算法的含噪图像分割

图像中的噪声会直接影响图像分割质量,为快速、准确地识别含噪图像中的目标,提出一种基于直方图预处理与BF算法的含噪图像分割方法。该方法通过小波变换抑制图像中的噪声,分析增强图像的直方图特点以缩小分割阈值的分布范围,以二维最大类间方差为原则设计分割目标函数,利用BF算法快速搜索最优分割阈值。实验结果表明,该方法在收敛速度、稳定性和分割效果三个方面均优于基于遗传算法、人工鱼群算法等其他群体智能的分割方法。     

一种基于低对比度图像的车辆检测算法

提出一种基于低对比度图像的车辆检测算法。对图像分割算法得到的感兴趣区域(ROI)进行预处理,利用Haar小波特征提取算法提取ROI的图像边缘及纹理特征,利用支持向量机对ROI进行车辆检测。实验结果表明,该方法对车辆检测率达到90.6%,误报率为3.8%。通过再学习还可以进一步提高算法的识别性能。     

基于均匀区域分割的图像检索研究

为减少图像分割准确性对基于内容的图像检索效率的影响,提出了一种基于均匀区域分割的图像检索算法。首先对图像进行均匀区域划分,提取其区域直方图颜色特征和Gabor小波纹理特征,再利用与所提取的图像特征相适应的相似性度量实现有效检索。实验结果表明,与SIMPLIcity系统相比,该算法平均检索性能提高了3.6%,具有良好的平均查找率。