自适应红外图像直方图均衡增强算法

针对红外图像的特点,本文提出了一种自适应红外图像直方图均衡增强算法。该方法根据原始图像的直方图,自适应地构造出一个加权函数对原始图像的直方图进行加权处理,然后采用加权后的直方图对原始图像进行直方图均衡化。算法不需要人为指定阈值,而且克服了传统直方图均衡提升红外图像背景的缺点。实验结果表明,该算法对红外图像具有较好的增强效果,能够有效地抑制图像的背景,突出目标。     

自适应红外图像直方图均衡增强算法

针对红外图像的特点,本文提出了一种自适应红外图像直方图均衡增强算法.该方法根据原始图像的直方图,自适应地构造出一个加权函数对原始图像的直方图进行加权处理,然后采用加权后的直方图对原始图像进行直方图均衡化.算法不需要人为指定阈值,而且克服了传统直方图均衡提升红外图像背景的缺点.实验结果表明,该算法对红外图像具有较好的增强效果,能够有效地抑制图像的背景,突出目标.     

基于图像信息熵统计直方图的图像增强算法

目的为了解决图像因亮度较大造成的成像效果不佳、局部细节不清楚等问题。方法将直方图均衡化技术(Histogram Equalization, HE)引入图像信息熵域,提出对比度弱化的图像信息熵统计直方图自适应均衡化算法(Contrast-reduced Adaptive Entropy Histogram Equalization, CRAEHE)。以各个灰度级信息熵统计值为基础,先将原图像分割成若干个子区域,对每个子区域的灰度信息熵统计值进行阈值截取,补充到子区域内各个灰度级上,再对子区域进行信息熵直方图均衡化处理。采用USC-SIPI和CBSD432数据集图像,用图像灰度均值、标准差、平均梯度、信息熵等参数对实验样本进行质量评价。结果文中算法处理结果较原图灰度均值下降了7.94%,标准差平均提高了52.22%,信息熵平均提高了19.86%,平均梯度提高了57.19%。结论文中算法增强了选自数据集里的过亮图像的细节,并使图像整体细节与质量都得到了改善,该算法的处理结果较其他处理实验样本的主观质量提升明显,对光照强度适应范围广。     

一种小波域的图像增强算法

微弱图像具有对比度低、噪声高、质量差等特点,一定程度上影响了图像的观察和使用。因此,提出一种小波域的图像增强算法,通过对微弱图像多尺度、多分辨率的小波变换分离各维度小波系数,对低频小波系数进行直方图均衡化,高频小波系数进行Canny算法提取边缘,最后将处理后的各维度小波系数进行图像重构以实现图像增强。并选取了3幅微弱图像,将其经所提出的算法及几种传统经典图像增强算法增强后的图像进行实验仿真对比。仿真结果表明,在主观评价上,所提算法增强后的图像的细节更加丰富,视觉感受更加平滑自然;客观评价指标中信息熵的值也都是最大的,分别是4.989 3,3.741 5,4.796 1,信息丰富度最高;而峰值信噪比和图像质量测量函数的数据表明所提算法增强图像的强度适中,整体性较好。可见,所提出的针对微弱图像的增强算法能够在视觉效果上和图像信息上进行有效的图像增强。     

对CT图像的增强方法研究

图像增强是图像处理中一个重要的内容,在图像生成、传输或变换的过程中,由于多种因素的影响,造成图像质量下降、图像模糊、特征淹没,给分析和识别带来困难。因此,按特定的需要将图像中感兴趣的特征有选择地突出,衰减不需要的特征,提高图像的可懂度是图像增强的主要内容。研究对医学CT图像的图像增强方法,主要是对空域方法和频域方法两种方法的研究。     

关于数字图像处理中直方图均衡化的探讨

直方图均衡化就是把一已知灰度概率分布的图像经过一种变换,使之演变成一幅具有均匀灰度概率分布的新图像。它是以累积分布函数变换法为基础的直方图修正法。分析和总结灰度直方图的均衡化算法并通过MATLAB实验验证该方法能有效达到图像增强的目的。     

基于FPGA的实时红外图像处理方法研究

文章在深入分析各种数字图像处理方法的基础上,采用了一种新的中值算法对传统红外图像处理方法进行了改进,有效地改善了数据的处理结果并明显地降低了系统逻辑资源的占用.此外,还通过FPGA板卡对本算法进行验证.实验结果表明,本系统设计的算法能够很好地完成大容量数据流的实时处理,达到了预期的设计目标.     

一种改进的声呐图像自适应增强算法

针对声呐图像增强算法研究较少等问题，提出了一种具有较强自适应能力改进图像增强算法，该算法通过自适应选择方差最小的滑动窗口作为当前像素点的增强处理窗口，并自适应判别像素点所属的区域类别，以进行相应的增强处理。仿真与现有算法的结果对比表明，本方法具有算法简单、易于实现等特点，且增强效果可较好地满足视觉效果的需求。     

一种有效的红外图像中人造目标分割方法

提出一种红外图像单阈值分割方法。为了减少计算量,结合先验信息选择包含待分割目标的感兴趣区域,利用Bezier曲线法平滑感兴趣区域直方图的噪声;对平滑后的感兴趣区域的直方图求解其曲率曲线,用曲率曲线的波峰所对应的灰度值作为初始分割阈值;基于先验信息从初始分割阈值中确定最佳分割阈值并进行初步分割。为了弥补单纯利用阈值法分割的缺陷,结合上述分割结果和目标的边缘信息得到封闭性良好的完整目标的二值图像。实验结果表明,提出的方法能快速有效地将红外目标从复杂的背景中分割出来,算法的计算复杂度为O(MN)。     

基于RBF神经网络的低对比度图像自适应增强算法

针对低对比度图像增强问题,提出了一种将直方图修正与RBF神经网络相结合的图像对比度增强算法。首先由原始图像获得与其邻域存在对比度的像素的条件概率直方图,通过调整两个增强参数可以改变条件概率直方图和均匀分布直方图的权重,生成新的直方图对图像进行增强。采用RBF神经网络建立图像特征与两个增强参数之间的非线性映射关系。根据图像本身的特征快速获得增强参数,从而实现图像的自适应增强。该方法计算量小,实时性强,应用范围广,有较强的自适应性。     

An improved adaptive detail enhancement algorithm for infrared images based on guided image filter

Detail enhancement algorithms are important for raw infrared images to improve their overall contrast and highlight important information in them. To solve the problems that current algorithms like GF&DDE have, an improved adaptive detail enhancement algorithm for infrared images based on a guided image filter is proposed in this paper. It chooses the threshold for the base layer image adaptively according to the histogram statistical information and adjusts the mapping range of the histograms according to the dynamic range of the image. Besides, the detail layer is handled by a simpler adaptive gain control method to achieve the good detail enhancement effect. Finally, the base layer and the detail are merged according to the approximate proportion of the background and the details. Experimental results show that the proposed algorithm can adaptively and efficiently enhance different dynamic range images in different scenarios. Moreover, this algorithm has high real-time performance.     

改善劣质实时图像预处理效果的优选法研究

针对某次实际飞行实验条件下所采集的有较严重问题的CCD实时景像图预处理算法研究问题，提出一种优选法。该方法先利用已有的Photoshop图形处理软件与人工手动调节相结合对原始图像进行处理，得到期望图像，再根据原图像的具体问题和已有的先验知识选择几种可能的预处理方法对原图像进行仿真，将所得图像与期望图像进行对比选出最适合处理此种劣质图像数据的优化预处理算法。将该算法应用于本次飞行实验数据上，飞行航线的匹配概率由5．41％提高到了86．48％，结果表明本文提出的优选法具有可行性和实用性。     

实时图像的电子消旋系统

为了消除图像旋转对准确进行目标的自动识别和跟踪带来的影响,提出了一种基于FPGA的电子学消旋方法。该方法利用旋转算法将原图像反向旋转相应的角度,再用双线性插值方法进行重采样,从而得到消旋后的图像。在此基础上构建了以XC2S200-5PQ208为核心处理器的实时图像消旋系统。这种电子学的消旋方法能够克服光学消旋系统加工困难、功耗大、角度分辨率低、体积大等严重不足之处。实验结果表明,该系统能够成功地对256×256×8bit的灰度图像进行实时消旋处理,其消旋角的分辨率最小可达到3′,最大像素误差小于一个像素。     

透火焰红外数字全息图像的分辨率增强算法

近年来,高温干扰遮蔽情况下利用红外热成像与数字全息成像相结合的新技术观察火场中目标成为时下的研究重点。理论上火焰和浓烟对长波长的红外数字全息成像没有影响,但在现实火场环境中,燃烧物的大颗粒灰尘将会干扰光路,严重增加了全息图重建图像的噪声。本文提出了一种新的图像处理算法来抑制红外数字全息重建的噪声。该算法利用双边滤波器配合拉普拉斯金字塔算法将全息重建图像的细节和能量层分开,再对细节层进行滤波,然后用反向拉普拉斯金字塔算法将分离的层叠加回重建图像中,从而提高重建像的分辨率,并通过模拟火场环境验证了该算法对改善红外数字全息图重建像的分辨率具有显著效果。     

Visualization strategies for infrared spectroscopic images

Although infrared imaging is becoming more commonplace and publications demonstrating its utility are on the rise, only a small portion of the literature involves visualization strategies and techniques. In order to fully realize the potential of imaging, visualization of the data in the form of images needs to be examined more thoroughly. Visualization techniques are discussed using the dynamic process of polymer dissolution. The dissolution of poly(ethylene oxide)(PEO) was captured as a series of images showing the changes of the polymer front brought about by the dissolving solvent. Using a unique infrared band for both the polymer and solvent, each species is tracked through the entire experiment. The ability to reconstruct the dissolution from the spatially resolved infrared data proves very valuable. However, the processing of the data is not trivial and steps must be taken to ensure that the images best display the specific attributes of the species. Scaling and color mapping are demonstrated to be two ways to achieve excellent imagery.     

Contrast enhancement using real coded genetic algorithm based modified histogram equalization for gray scale images

Histogram equalization is a well‐known technique used for contrast enhancement. The global HE usually results in excessive contrast enhancement because of lack of control on the level of contrast enhancement. A new technique named modified histogram equalization using real coded genetic algorithm (MHERCGA) is aimed to sweep over this drawback. The primary aim of this paper is to obtain an enhanced method which keeps the original brightness. This method incorporates a provision to have a control over the level of contrast enhancement and applicable for all types of image including low contrast MRI brain images. The basic idea of this technique is to partition the input image histogram into two subhistograms based on a threshold which is obtained using Otsu's optimality principle. Then, bicriteria optimization problem is formulated to satisfy the aforementioned requirements. The subhistograms are modified by selecting optimal contrast enhancement parameters. Finally, the union of the modified subhistograms produce a contrast enhanced and details preserved output image. While developing an optimization problem, real coded genetic algorithm is applied to determine the optimal value of contrast enhancement parameters. This mechanism enhances the contrast of the input image better than the existing contemporary HE methods. The quality of the enhanced brain image indicates that the image obtained after this method can be useful for efficient detection of brain cancer in further process like segmentation, classification, etc. The performance of the proposed method is well supported by the contrast enhancement quantitative metrics such as discrete entropy and natural image quality evaluator. © 2015 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 25, 24–32, 2015     

Digital enhancement of video images for NDT

Due to recent advances in micro-electronics, many digital image enhancement techniques can now be readily applied at standard video-rates using commercially available hardware. These techniques are being increasingly applied in the field of nondestructive testing, in particular to methods that generate TV-type video images, such as real-time radiography and pulse-video thermography. The latest techniques used by the National NDT Centre at Harwell are described and are illustrated by examples from three application areas.     

Principal-component characterization of noise for infrared images

Principal-component decomposition is applied to the analysis of noise for infrared images. It provides a set of eigenimages, the principal components, that represents spatial patterns associated with different types of noise. We provide a method to classify the principal components into processes that explain a given amount of the variance of the images under analysis. Each process can reconstruct the set of data, thus allowing a calculation of the weight of the given process in the total noise. The method is successfully applied to an actual set of infrared images. The extension of the method to images in the visible spectrum is possible and would provide similar results.     

Passive Fourier-transform infrared spectroscopy of chemical plumes: an algorithm for quantitative interpretation and real-time background removal

We present a ratioing algorithm for quantitative analysis of the passive Fourier-transform infrared spectrum of a chemical plume. We show that the transmission of a near-field plume is given by τ(plume) = (L(obsd) - L(bb-plume))/(L(bkgd) - L(bb-plume)), where τ(plume) is the frequency-dependent transmission of the plume, L(obsd) is the spectral radiance of the scene that contains the plume, L(bkgd) is the spectral radiance of the same scene without the plume, and L(bb-plume) is the spectral radiance of a blackbody at the plume temperature. The algorithm simultaneously achieves background removal, elimination of the spectrometer internal signature, and quantification of the plume spectral transmission. It has applications to both real-time processing for plume visualization and quantitative measurements of plume column densities. The plume temperature (L(bb-plume)), which is not always precisely known, can have a profound effect on the quantitative interpretation of the algorithm and is discussed in detail. Finally, we provide an illustrative example of the use of the algorithm on a trichloroethylene and acetone plume.     

基于FPGA的实时脉冲参数检测系统的设计

提出了一种基于可编程逻辑硬件结构的实时脉冲参数检测系统的方案,该方案对高速脉冲信号的采样序列建立微分门限算法,并以可编程逻辑硬件方式实现实时高效地获取脉冲特征参数。文中以大规模可编程器件为设计基础,以硬件描述语言为设计工具,详细地阐述了各功能模块的设计思路和具体实现方法,并进行了时效分析和功能仿真,为实时脉冲参数检测提供了一个简单有效的操作方案。