核素肺通气/灌注显像的伪影识别与分割

SPECT核素肺通气/灌注显像的定量分析是诊断肺动脉栓塞的一种有效手段。对通气/灌注图像中肺部区域能否准确定位及有效分割是整个定量分析的前期工作与基础。提出一种均值检测法实现核素肺部成像的伪影识别及感兴趣区ROI提取,并基于二维最大熵理论确定阈值分割出双肺影像。通过对16例正常人和10例肺栓塞病患的SPECT通气/灌注图像进行处理,该方法提取效率高、运算速度快,较好地实现了肺部感兴趣区定位与分割。     

Recursive algorithm based on fuzzy 2-partition entropy for 2-level image thresholding

The fuzzy c-partition entropy approach for threshold selection behaves well in segmenting images. But the size of search space increases very rapidly when the number of parameters needed to determine the membership function increases. The computation complexity of the fuzzy 2-partition entropy approach is bounded by O(L³). In this paper, a recursive scheme which decreases the computation complexity of the basic algorithm to O(L²) is proposed. The approach does not need the calculation of the membership function. The processing time of each image is reduced from more than 5 min to less than 20 s.     

C#实现彩色图像分割

针对图像分析应用日益广泛的现状,基于阈值法对彩色图像实现分割进行论述。介绍图像分割基本概念,讲述彩色图像直方图阈值分割方法,利用二维直方图方便地寻找彩色图像阈值,最后通过C#可行的程序稳定、准确地实现彩色图像阈值分割。     

基于循环神经网络的通信卫星故障检测

随着现代航天事业的飞速发展,通信卫星的结构日益复杂,其故障也逐渐增多,通信卫星的故障检测已成为当前航天领域关注的重点问题。目前,各大航天机构对故障的检测仍以简单的上下限阈值检测为主,只能检测出少部分特定的故障。早期利用传统机器学习算法进行检测的研究也仅能检测出数量特征上的故障。针对传统的机器学习算法难以有效学习遥测数据趋势变化的问题,文中提出了基于长短时记忆(Long Short-term Memory,LSTM)网络的阈值化方法。通过LSTM预测模型来学习卫星遥测数据的趋势变化,同时以最大化相关系数与F1分数的方式为多维遥测数据的故障判定确定合适的阈值,此方式能够有效地通过卫星遥测数据的趋势变化来判断故障。实验数据采用某航天机构提供的时长为2年的24维通信卫星遥测数据,其核心模型LSTM网络在NVIDIA Corporation GP102[TITAN Xp]上训练,最终整体模型的准确率为99.34%,查准率为81.93%,查全率为94.62%。同时,与传统机器学习算法以及基于LSTM的非阈值方法进行对比,该模型的精度明显更高。实验结果表明,LSTM网络能够高效地学习到卫星遥测数据的...     

A fast recursive algorithm based on fuzzy 2-partition entropy approach for threshold selection

The fuzzy c-partition entropy approach for threshold selection is an effective approach for image segmentation. The approach models the image with a fuzzy c-partition, which is obtained using parameterized membership functions. The ideal threshold is determined by searching an optimal parameter combination of the membership functions such that the entropy of the fuzzy c-partition is maximized. It involves large computation when the number of parameters needed to determine the membership function increases. In this paper, a recursive algorithm is proposed for fuzzy 2-partition entropy method, where the membership function is selected as S-function and Z-function with three parameters. The proposed recursive algorithm eliminates many repeated computations, thereby reducing the computation complexity significantly. The proposed method is tested using several real images, and its processing time is compared with those of basic exhaustive algorithm, genetic algorithm (GA), particle swarm optimization (PSO), ant colony optimization (ACO) and simulated annealing (SA). Experimental results show that the proposed method is more effective than basic exhaustive search algorithm, GA, PSO, ACO and SA.     

An improved wavelet-based speech enhancement by using speech signal features

This paper presents a new speech enhancement system that works in wavelet domain. The core of system is an improved WaveShrink module. First, different parameters of WaveShrink are studied; then, based on the features of speech signal, an improved wavelet-based speech enhancement system is proposed. The system uses a novel thresholding algorithm, and introduces a new method for threshold selection. Moreover, the efficiency of system has been increased by selecting more suitable parameters for voiced, unvoiced and silence regions, separately. The proposed system has been evaluated on different sentences under various noise conditions. The results show a plausible improvement in performance of system, in comparison with similar approaches.     

Color image segmentation: advances and prospects

Image segmentation is very essential and critical to image processing and pattern recognition. This survey provides a summary of color image segmentation techniques available now. Basically, color segmentation approaches are based on monochrome segmentation approaches operating in different color spaces. Therefore, we first discuss the major segmentation approaches for segmenting monochrome images: histogram thresholding, characteristic feature clustering, edge detection, region-based methods, fuzzy techniques, neural networks, etc.; then review some major color representation methods and their advantages/disadvantages; finally summarize the color image segmentation techniques using different color representations. The usage of color models for image segmentation is also discussed. Some novel approaches such as fuzzy method and physics-based method are investigated as well.     

基于阈值法与区域生长法综合集成的图像分割法

本文首先对一类因照明不均匀使得图像质量受到一定影响的这样一类比较复杂的图像特点及其分割难点做分析,然后提出一种新的基于阈值法与区域生长法综合集成的图像分割方法。实验结果表明,该分割算法不仅适用于较简单的图像分割问题,而且适用于分割因照明不均匀使得图像质量受到一定影响的这样一类较复杂的图像的分割,且分割时间可进一步缩短。     

把彩色图象处理成由图案组成的二色图象

根据抖动原理,巧妙定义抖动矩阵,把彩色图象灰度比,结合特定图案的抖动矩阵对灰度图象进行二值化处理,最后使彩色图象变成了一幅有特殊图案组成的二色图象,并解决了抖动过程中的一些特殊问题。     

基于二维阈值化和遗传算法的图像分割方法

本文以二维最大熵为例,讨论了如何利用遗传算法和二维直方图进行图像阈值的自动选取。实验结果表明,利用遗传算法可以有效地提高原有图像阈值选取方法的速度。