A novel adaptive morphological approach for degraded character image segmentation

This work proposes a novel adaptive approach for character segmentation and feature vector extraction from seriously degraded images. An algorithm based on the histogram automatically detects fragments and merges these fragments before segmenting the fragmented characters. A morphological thickening algorithm automatically locates reference lines for separating the overlapped characters. A morphological thinning algorithm and the segmentation cost calculation automatically determine the baseline for segmenting the connected characters. Basically, our approach can detect fragmented, overlapped, or connected character and adaptively apply for one of three algorithms without manual fine-tuning. Seriously degraded images as license plate images taken from real world are used in the experiments to evaluate the robustness, the flexibility and the effectiveness of our approach. The system approach output data as feature vectors keep useful information more accurately to be used as input data in an automatic pattern recognition system.     

二维直方图图形统计分析的分割方法

一维阈值分割方法对噪声污染的图像很难达到理想的分割效果。二维直方图的分割方法结合了灰度和空间信息使分割精度提高,但计算复杂度急剧增加,并且传统二维直方图的方法对噪声和边缘像素的处理不够准确。改进了二维直方图的构造方法,采用自适应滤波器平滑噪声的同时更高效地保持了图像边缘和高频细节信息。运用改进的Hough变换对二维直方图进行图形统计分析,并搜索二维直方图的平面分割线,将二维直方图划分为不同的分割区域。实验结果表明改进的算法对噪声污染的图像有更好的抗噪能力,分割也更加准确。     

利用Kolmogorov-Smirnov统计的区域化图像分割

目的 为了在未知或无法建立图像模型的情况下,实现统计图像分割,提出一种结合Voronoi几何划分、K-S(Kolmogorov-Smirnov)统计以及M-H(Metropolis-Hastings)算法的图像分割方法.方法 首先利用Voronoi划分将图像域划分成不同的子区域,而每个子区域为待分割同质区域的一个组成部分,并利用K-S统计定义类属异质性势能函数,然后应用非约束吉布斯表达式构建概率分布函数,最后采用M-H算法进行采样,从而实现图像分割.结果 采用本文算法,分别对模拟图像、合成图像、真实光学和SAR图像进行分割实验,针对模拟图像和合成图像,分割结果精度均达到98%以上,取得较好的分割结果.结论 提出基于区域的图像分割算法,由于该算法中图像分割模型的建立无需原先假设同质区域内像素光谱测度的概率分布,因此提出算法具有广泛的适用性.为未知或无法建立图像模型的统计图像分割提供了一种新思路.     

一种新的人民币号码图像分割方法

针对人民币号码图像前景与背景分离问题,在对现有的几种分割方法进行分析实验的基础上,提出了一种新的人民币号码分割方法,即基于形态学处理的直方图阈值分割人民币号码图像的方法,对目标和背景混杂在一起,阈值选取困难的图像,先进行形态学变换,处理后的直方图阈值就很好选取了.实验结果表明,该方法的错误分割率明显低于普通的直方图阈值...     

工业检测图像灰度波动变换自适应阈值分割算法

工业检测图像经常受到不均光照的影响,对该类图像局部自适应分割算法比全局算法能产生更好的分割效果. 但局部算法中基于分块的算法对分块方法缺乏指导,而基于邻域的算法容易在背景或前景内部产生误分. 针对上述缺点,本文提出了一种多方向灰度波动变换的自适应阈值分割算法. 该算法先从多个方向依照灰度波动对图像进行转换,构造以多维向量为基础的灰度波动变换矩阵, 然后利用主成分分析法(Principal component analysis, PCA)将高维向量压缩至一维并生成变换图像,最后运用Otsu算法分割变换图像. 该算法无需分块,并且仅需波动幅度阈值和布尔型背景色两个参数. 实验结果表明,该算法能够有效减少不均光照对工业检测图像分割的影响, 与Niblack法、Sauvola法等几种局部算法相比,该法在分割效果上具有了明显的提升.     

自适应多阈值图像分割算法

本文提出了一种新的自适应多阈值图像分割算法.它首先利用势基函数对-维灰度直方图拟合,通过势函数聚类自动确定划分类数;然后在灰度共生矩阵的基础上,依据形状连通度准则,求得使形状连通度最大的一组分割阈值;最后按该组分割阈值执行多阈值图像分割.理论分析和实验结果都表明该算法较传统阈值分割算法优越,具有运算速度快、划分效果好、抗干扰性强的特点.     

Construction and verification of retinal vessel segmentation algorithm for color fundus image under BP neural network model

To improve the accuracy of retinal vessel segmentation, a retinal vessel segmentation algorithm for color fundus images based on back-propagation (BP) neural network is proposed according to the characteristics of retinal blood vessels. Four kinds of green channel image enhancement results of adaptive histogram equalization, morphological processing, Gaussian matched filtering, and Hessian matrix filtering are used to form feature vectors. The BP neural network is input to segment blood vessels. Experiments on the color fundus image libraries DRIVE and STARE show that this algorithm can obtain complete retinal blood vessel segmentation as well as connected vessel stems and terminals. When segmenting most small blood vessels, the average accuracy on the DRIVE library reaches 0.9477, and the average accuracy on the STARE library reaches 0.9498, which has a good segmentation effect. Through verification, the algorithm is feasible and effective for blood vessel segmentation of color fundus images and can detect more capillaries.

     

On the performance of nature inspired algorithms for the automatic segmentation of coronary arteries using Gaussian matched filters

This paper presents a comparative analysis of four nature inspired algorithms to improve the training stage of a segmentation strategy based on Gaussian matched filters (GMF) for X-ray coronary angiograms. The statistical results reveal that the method of differential evolution (DE) outperforms the considered algorithms in terms of convergence to the optimal solution. From the potential solutions acquired by DE, the area (A_z) under the receiver operating characteristic curve is used as fitness function to establish the best GMF parameters. The GMF-DE method demonstrated high accuracy with A_z = 0.9402 with a training set of 40 angiograms. Moreover, to evaluate the performance of the coronary artery segmentation method compared to the ground-truth vessels hand-labeled by a specialist, measures of sensitivity, specificity and accuracy have been adopted. According to the experimental results, GMF-DE has obtained high coronary artery segmentation rate compared with six state-of-the-art methods provided an average accuracy of 0.9134 with a test set of 40 angiograms. Additionally, the experimental results in terms of segmentation accuracy, have also shown that the GMF-DE can be highly suitable for clinical decision support in cardiology.     

复杂光照下DPM图像自适应多阈值分割方法研究

复杂工况下,CCD相机采集到的DPM（Direct Part Mark）工业二维码图像受光照影响易出现大片光斑或阴影区域,造成DPM区域的信息遗漏,从而导致识别困难。为此,提出一种基于分段直方图凹度分析的多阈值自适应分割算法。首先在灰度直方图平滑的基础上计算出系列局部峰值,并借此完成直方图分段,再递推计算出每分段区域下凹处的分割阈值。其次通过引入基于阈值点局部区域信息的修正因子,使分割阈值自适应变化而更适用于局部对比度较低的状况。实验结果表明,该方法分割效果优于经典的阈值分割算法,平均运行效率比最快的多阈值分割算法提高17.75倍。经自适应局部阈值分割后,DPM图像复杂光照区域有用信息得以增强,缺失信息得以弥补,为后续的对象识别奠定基础。该方法也可推广于对比度多变的图像增强。     

基于同态滤波与Curvelet变换的钻孔图像自适应增强

针对岩石数字钻孔图像存在的光照不均、图像中岩石表面边缘细节模糊等情况,提出了一种钻孔图像自适应增强算法.对原图进行同态滤波;使用Curvelet变换分解原图与滤波后的图像,对两者的低频子带使用系数直方图匹配算法,将前者与后者的直方图进行匹配,改善光照不均的影响;对原图的高频子带使用自适应的阈值进行滤波,同时利用自适应增强函数进行增强;使用Curvelet反变换重构得到增强后的图像.实验结果表明:算法可以有效地改善钻孔图像光照不均的问题,增强图像中物体的边缘信息,在主观视觉效果和图像客观评价指标上相对于其他算法均有一定优势.     

噪声不敏感的柱状图特征描述符及其在图像检索中的应用

基于内容的图像检索方法往往将图片的内容表示成柱状图,根据图片柱状图之间的相似性进行图片的检索。数码图片中包含的噪声使得柱状图变得平滑,从而使图片之间变得更为相似,这增加了返回结果中包含的图片数量。为了进一步提高图片检索的性能,提出了一种对噪声不敏感的柱状图特征描述符,并应用该特征描述符进行图像之间的相似性匹配。首先将图片中的噪声描述为平稳附加高斯白噪声,并给出了相应的柱状图表示;然后通过随机变量的原点矩定义了柱状图的特征描述符,并分析了如何应用特征描述符恢复原始图片的柱状图。在算法的性能验证过程中,将提出的方法与4种相关算法进行比较,应用两个真实的图片数据库的图像检索实验验证了所提方法的有效性。     

几种常用CT图像分割算法分析和探讨

图像分割是数字图像处理的一个经典难题。其分割质量的好坏直接影响到图像处理的后续工作。因而在理论研究和实际应用中受到研究人员的广泛重视。本文在总结了过去的分割方法基础上,就目前常用几种分割方法进行实验研究。主要包括阈值分割、LOG算子分割、FCM聚类分割、分水岭分割,并结合CT图像进行图像分割。文章阐述了各种分割方法的概念及原理,并在此基础上对分割结果进行了分析和探讨,得出各种方法的优点和不足。这些实验结论将为后续研究提供科学依据。     

基于多特征融合的花卉图像检索

以植物花卉图像为研究对象,对植物花卉图像在区域分割、特征提取、基于内容的雷同图像过滤以及基于SVM的植物花卉图像检索等方面进行了系统、深入和较为全面的研究。首先为保证检索效果,提出了基于Canny边缘的雷同图片过滤算法对花卉图像库中的雷同图片进行过滤。然后提出基于2RGB混合颜色模型的自适应阂值分割算法来对花卉图像进行分割。对特征提取采用多特征融合的方法,其中针对形状特征提出了基于HSV颜色模型的加权不变矩,并提出了结合形状特征与纹理特征的边缘LBP算子。通过在花卉图像库进行的实验表明,提出的若干方法都是有效的。     

复杂背景下的阈值插值方法

图像分割是进行图像处理的关键步骤。目前很多图像分割的技术都需要人工干预，而且是针对单纯的图像背景才能达到目标。为了解决有复杂背景的图像的分割问题，采用自适应阈值(阈值插值)的方法，并对其加以改进，用迭代阈值判断子图像的直方图是否是双峰分布，同时确定直方图有双峰的子图像的阈值；用双线性插值的方法确定直方图非双峰分布的予图像的阈值，使这种算法在实际中可行。实验证明这种方法适用于复杂背景的图像分割，且通用性比较好。     

基于天空分割的单幅交通标志图像去雾算法

针对现有去雾算法应用于交通标志图像时容易产生信息丢失、色彩失真等问题,导致去雾后图像质量较低,不能很好地满足交通标志识别系统（TSRS）的实际应用需求,提出一种基于天空分割的单幅交通标志图像去雾算法。根据大津算法结合图像灰度特征得到自适应阈值实现天空区域和非天空区域的准确分割;非天空区域采取改进的暗通道先验算法去雾,引入自适应中值滤波和快速双边滤波联合的方法优化透射率,天空区域则采取直方图均衡化算法去雾;通过融合得到无雾图像;引入高斯滤波对严重降质图像进行去雾后清晰化处理。实验结果表明,去雾后图像在峰值信噪比等多个客观评价指标上的综合表现优于其他几种去雾方法,所提算法在保证较低的时间复杂度的同时,能有效地保留图像信息,还原出清晰的真实图像,满足TSRS的实际应用需求。     

基于CT心脏图像的腔体区域分割新算法

在心脏图像处理中,为解决心脏四腔过分割问题,使用基于直方图的多阈值分割和标记分水岭分割相结合的新方法.由于CT心脏腔体区域灰度十分相似,组织相互连通,采取单一阈值分割无法得到目标区域,新算法使用多阈值分割,根据图像对应的直方图选择合适的阈值,并将分割结果作为基于标记的分水岭分割算法的输入图像,最终获得心脏的腔体区域,最后,通过重建得到左心房心室的三维结构图.而与其他分水岭改进方法相比,该算法以基于直方图的多阈值分割为前提,标记提取更为准确,目标组织边界清晰,能够获得更加理想的分割结果,有效降低了仅使用分水岭算法存在的过分割现象.     

Adaptive spatial information-theoretic clustering for image segmentation

The incorporation of spatial context into clustering algorithms for image segmentation has recently received a significant amount of attention. Many modified clustering algorithms have been proposed and proven to be effective for image segmentation. In this paper, we propose a different framework for incorporating spatial information with the aim of achieving robust and accurate segmentation in case of mixed noise without using experimentally set parameters based on the original robust information clustering (RIC) algorithm, called adaptive spatial information-theoretic clustering (ASIC) algorithm. The proposed objective function has a new dissimilarity measure, and the weighting factor for neighborhood effect is fully adaptive to the image content. It enhances the smoothness towards piecewise-homogeneous segmentation and reduces the edge blurring effect. Furthermore, a unique characteristic of the new information segmentation algorithm is that it has the capabilities to eliminate outliers at different stages of the ASIC algorithm. These result in improved segmentation result by identifying and relabeling the outliers in a relatively stronger noisy environment. Comprehensive experiments and a new information-theoretic proof are carried out to illustrate that our new algorithm can consistently improve the segmentation result while effectively handles the edge blurring effect. The experimental results with both synthetic and real images demonstrate that the proposed method is effective and robust to mixed noise and the algorithm outperforms other popular spatial clustering variants.     

Nonparametric Bayesian Image Segmentation

Image segmentation algorithms partition the set of pixels of an image into a specific number of different, spatially homogeneous groups. We propose a nonparametric Bayesian model for histogram clustering which automatically determines the number of segments when spatial smoothness constraints on the class assignments are enforced by a Markov Random Field. A Dirichlet process prior controls the level of resolution which corresponds to the number of clusters in data with a unique cluster structure. The resulting posterior is efficiently sampled by a variant of a conjugate-case sampling algorithm for Dirichlet process mixture models. Experimental results are provided for real-world gray value images, synthetic aperture radar images and magnetic resonance imaging data.     

Technique for preprocessing of digital mammogram

Digital mammogram has emerged as the most popular screening technique for early detection of breast cancer and other abnormalities in human breast tissue. It provides us opportunities to develop algorithms for computer aided detection (CAD). In this paper we have proposed three distinct steps. The initial step involves contrast enhancement by using the contrast limited adaptive histogram equalization (CLAHE) technique. Then define the rectangle to isolate the pectoral muscle from the region of interest (ROI) and finally suppress the pectoral muscle using our proposed modified seeded region growing (SRG) algorithm. The proposed algorithms were extensively applied on all the 322 mammogram images in MIAS database resulting in complete pectoral muscle suppression in most of the images. Our proposed algorithm is compared with other segmentation methods showing superior results in comparison.     

固体推进剂药柱图像的自适应阈值分割方法

以固体推进剂药柱内窥镜图像表面缺陷的自动检测为例,在分析了此类图像特征的基础上,提出了一种利用梯度直方图信息的图像自适应阈值分割算法。通过实例,与原自适应直方图阈值分割算法和固定阈值分割算法相比较,结果表明：该算法采用可动态调整的形态学梯度算子计算梯度直方图,充分利用了图像的边缘信息和缺陷内部灰度分布不均匀的特性,算法简单,适应性广,具有实时准确分割图像的特点。