Real-time digital image enhancement

A programmable system for enhancing monocular and stereographic images at video rates is presented. The system provides both automatic and interactive enhancement modes based on histogram modification and intensity mapping techniques. Experimental results which illustrate enhancement capabilities under a variety of scene types and conditions are described.     

MATLAB在数字图像增强中的应用

基于数字图像增强对图像处理的重要性,将计算软件MATLAB应用于数字图像增强中,给出了用这一软件完成图像的对比度增强、直方图均衡化、平滑滤波、锐化等操作的示例,并给出了处理前后的对照图像。同时论述了MATLAB在进行图像处理试验时简洁、高效的特点。     

Data structures and computational organization in digital image enhancement

Two practical questions in developing an image enhancement computer program are considered: the data structure for the matrix of image samples, and computing the FFT of a large matrix. Experience in developing such programs is discussed, and characteristics of an enhancement program developed for the CDC 6600/7600 computers are described.     

Automatic image hanging protocol for chest radiographs in PACS.

Chest radiography is one of the most widely used techniques in diagnostic imaging. It comprises at least one-third of all diagnostic radiographic procedures in hospitals. However, in the picture archive and communication system, images are often stored with the projection and orientation unknown or mislabeled, which causes inefficiency for radiologists' interpretation. To address this problem, an automatic hanging protocol for chest radiographs is presented. The method targets the most effective region in a chest radiograph, and extracts a set of size-, rotation-, and translation-invariant features from it. Then, a well-trained classifier is used to recognize the projection. The orientation of the radiograph is later identified by locating the neck, heart, and abdomen positions in the radiographs. Initial experiments are performed on the radiographs collected from daily routine chest exams in hospitals and show promising results. Using the presented protocol, 98.2% of all cases could be hung correctly on projection view (without protocol, 62%), and 96.1% had correct orientation (without protocol, 75%). A workflow study on the protocol also demonstrates a significant improvement in efficiency for image display.     

一种数字图像增强系统的设计与实现

数字图像增强处理是根据特定的要求突出数字图像中感兴趣的部分,弱化和除去不感兴趣的内容,它是数字图像处理过程中的重要一环.利用MATLAB软件提供的图形用户界面开发环境和图像处理工具箱,开发了一个面向教学的可视化、开放性、交互性于一体的"数字图像增强系统".实际应用结果表明,该系统运行稳定、操作方便,可移植性和可扩展性强,具有一定的应用前景和较高的实用价值.     

基于模糊自适应算法的胸片图像增强研究

胸片图像增强是计算机辅助诊断的关键之一,更适合医生对病人的观察或机器的分析处理。本文在基于模糊理论的基础上,通过研究经典的Pal和King模糊增强算法中的不足,对胸片图像进行增强处理。提出了一种自适应阈值的广义模糊增强算法。将图像引入广义模糊空间;然后定义一个衡量图像质量标准的参数。改进的算法通过调节参数使图像更加清晰...     

一种红外图像细节增强算法

针对红外图像对比度低的特点提出一种红外图像细节增强算法,并对其进行了仿真。该算法首先利用腐蚀和膨胀以及均值滤波来消除散粒噪声,然后通过均值滤波得到低频图像,从而提取出细节图像,并且计算每个像素的权重,对细节图像进行有权重的直方图统计,通过幂级数变化降低背景的影响。仿真结果表明,此方法在不同情景下都能够取得较好的效果,并且由于该算法复杂度低,在硬件实现时需要的资源也较少,可以进行商用。     

高斯混合模型自适应微光图像增强

为了改善微光情况下可见光图像传感器输出图像的质量,提出了一种基于高斯混合模型的自适应微光图像增强算法。对图像的直方图进行混合高斯建模,应用改进的期望最大化算法对直方图拟合,从而获取高斯混合模型的最优参数,然后根据各个聚类的交点将直方图分区,最后确定输出图像所属聚类的映射关系,同时应用保持最大熵方法逼近人类视觉特性映射函数得到最终的增强图像。实验结果表明,此图像增强模型能自适应确定最佳聚类个数,提高直方图拟合的运算速度,一帧图像平均处理时间为0.37s,在相关信息熵和纹理信息等的客观评价中,增强结果明显优于传统方法,有效地提高了微光图像的对比度,同时保持了图像的细节。     

Motion detection and motion compensation for digital subtraction angiography image enhancement

For the enhancement of digital subtraction angiography (DSA) images, registration of mask and contrast image prior to subtraction is a pre-requisite. One of the main requirements of this task is that the region-of-interest used for the calculation of the registration parameters should contain the vascular structures of interest. This, however, is also one of the main problems in DSA because the contrasted vascular structures can be regarded as a distortion that makes the images to be compared dissimilar. In this paper we present a comparison between three frequently used similarity measures and histogram-based similarity measures. This reveals the advantages of the latter. The data-driven approach is especially suitable for registration of two images which are identical except for some structures visible in one but not in the other image. Based on an energy similarity measure, a motion vector field is obtained by template matching, which gives a set of homologous landmarks or control points in the mask and contrast image. A point-based registration is performed fitting the parameter of an appropriate transformation for patient motion correction. An affine and an elastic transformation are compared for an abdominal fluoroscopic scene.     

基于图像增强的改进自适应加权均值滤波算法

为了尽可能滤除图像中的椒盐噪声同时改善图像视觉效果,将改进自适应加权均值滤波与小波域图像增强技术有机结合,提出了一种具有增强效果的图像滤波算法。该算法分为滤波和滤波后处理两个阶段。滤波阶段,对经典均值滤波分别从噪声检测策略、权值计算机方法噪声滤波模版设计等方面进行适当改进,给出了具体实现步骤;滤波后处理阶段,首先将滤波后图像进行三层小波分解;然后构造出一种小波图像增强模型,根据小波系数的幅度值将其分为三个部分,分别进行不同程度的拉伸处理;最后进行拉伸后小波系数重构。将该滤波算法与经典均值滤波,加权均值滤波、自适应加权中值滤波等性能比较,实验结果表明,本文滤波算法在噪声滤除和图像细节保持方面,效果较好。     

Computer-aided diagnosis in chest radiography: a survey

The traditional chest radiograph is still ubiquitous in clinical practice, and will likely remain so for quite some time. Yet, its interpretation is notoriously difficult. This explains the continued interest in computer-aided diagnosis for chest radiography. The purpose of this survey is to categorize and briefly review the literature on computer analysis of chest images, which comprises over 150 papers published in the last 30 years. Remaining challenges are indicated and some directions for future research are given.     

小波变换域数字图像增强算法及实现

图像增强是数字图像预处理中的重要方法,其主要目的是改善视觉效果.小波变换在图像压缩和图像分割两个方面应用较为广泛,图像增强方面应用较少.现概括了图像增强的原理,阐述了图像增强的方法,分析了一种小波变换域的图像增强算法并在Matlab环境下仿真实现.该算法首先使用haar小波对图像进行2层分解,然后对低频部分进行增强,对高频部分进行衰减,实验结果证明这是对图像去噪和增强的一种有效方法.     

基于数据挖掘三维数字图像模糊增强系统设计

目前对于三维数字图像模糊增强使用的系统存在图像处理耗时过长的问题。为了解决此问题,设计基于数据挖掘三维数字图像模糊增强系统。设计系统整体框架包括电源模块、外围接口模块、核心处理模块以及存储模块。在整体框架基础上,使用ARM处理器,设计电源电路和外围接口电路,完成系统的框架搭建。利用数据挖掘技术对三维数字图像特征进行提取,并计算模糊特征值,通过模糊特征值和模糊隶属函数实现图像模糊增强,至此系统整体设计完成。测试结果表明,与传统的图像模糊增强系统相比,基于数据挖掘三维数字图像模糊增强系统的处理图像所耗时间缩短了25.86%,适合应用在三维数字图像增强中。     

基于图像处理的数字仪表字符自动识别研究

为提高数字仪表图像识别率,结合机器视觉技术,在图像预处理的基础上,提出一种PSO的LSSVM参数优化方案。在图像预处理阶段,采用Hough变换校正,并通过形态学处理和二值化,以提高图像采集的效率;然后采用连通域的方式实现对图像区域的定位分割,并通过七段码实现图像特征提取;针对数字仪表识别是多分类的问题,采用OAO分类法将LSSVM算法拓展到多分类,并引入PSO算法对LSSVM参数进行优化;最后以OpenCV开源库、MATLAB作为工具,对上述算法进行验证。结果表明,0~9数字字符识别率为99.2%,整体图像样本测试识别率为99.6392%,高于其他算法,体现了较好的识别效果。     

Data hiding technologies for digital radiography

Research on data hiding is demonstrating every day that several applications can benefit from this technology; among these, medical data management. In particular, embedding patient information into a medical image through data hiding could improve the level of security and confidentiality that is essential for the diffusion of medical information systems. The design of a data hiding system for such an application has to take into account specific requirements, the most important are: high payload to identifying reliably a patient; quality preservation of the watermarked image; robustness to content modification. According to this analysis, a comparison between different data hiding approaches is presented, to evaluate the most suitable algorithms for embedding patient information into digital radiographs. In particular two algorithms based on statistical decision theory have been compared with schemes following the new approach of modelling data hiding as communication with side-information at the transmitter. These methods have been tested and compared in the framework of digital radiographies management in order to identify their benefits and drawbacks.     

Peer group image enhancement

Peer group image processing identifies a "peer group" for each pixel and then replaces the pixel intensity with the average over the peer group. Two parameters provide direct control over which image features are selectively enhanced: area (number of pixels in the feature) and window diameter (window size needed to enclose the feature). A discussion is given of how these parameters determine which features in the image are smoothed or preserved. We show that the Fisher discriminant can be used to automatically adjust the peer group averaging (PGA) parameters at each point in the image. This local parameter selection allows smoothing over uniform regions while preserving features like corners and edges. This adaptive procedure extends to multilevel and color forms of PGA. Comparisons are made with a variety of standard filtering techniques and an analysis is given of computational complexity and convergence issues.     

Underwater image enhancement with image colorfulness measure

Due to the absorption and scattering effects of the water, underwater images tend to suffer from many severe problems, such as low contrast, grayed out colors and blurring content. To improve the visual quality of underwater images, we proposed a novel enhancement model, which is a trainable end-to-end neural model. Two parts constitute the overall model. The first one is a non-parameter layer for the preliminary color correction, then the second part is consisted of parametric layers for a self-adaptive refinement, namely the channel-wise linear shift. For better details, contrast and colorfulness, this enhancement network is jointly optimized by the pixel-level and characteristic-level training criteria. Through extensive experiments on natural underwater scenes, we show that the proposed method can get high quality enhancement results.     

DICOM数字乳腺仪图像一致性的自动检测

提出了一种基于DICOM标准的数字乳腺仪图像一致性的自动检测的实现方式,该方法可减少检测时间并降低人为误差。将描述自动检测工具的具体实现,验证实验以及自动检测工具的性能。该工具已经在GE公司数字乳腺仪部门得到应用,也可以应用到其他基于DICOM标准的数字图像医疗设备。     

图像通信中一种低照度彩色图像增强算法

针对低照度彩色图像细节模糊、亮度不高等问题,提出一种新的彩色图像增强算法。首先引入新传递函数改进传统同态滤波,然后,在RGB色彩空间上,分别对R、G、B分量用改进的同态滤波和对比度受限自适应直方图均衡（CLAHE）进行增强。接着,转换到HSV色彩空间,用非线性函数对亮度进行光照补偿,对饱和度进行1.5倍拉伸。最后恢复图像色彩信息。实验结果表明,新算法在保持图像细节的同时能够增强图像对比度,使图像清晰度更高。