SPIHT算法在DICOM图像压缩中的应用研究

DICOM图像文件的储存和传输一直是近代医学图像处理中一个比较热门的研究话题,其中较好的解决方案就是对DICOM图像进行压缩处理。文中通过对DICOM文件的数据结构进行分析,将DICOM文件拆分成图像数据部分和文本信息部分,然后采用9/7提升小波变换对拆分出来的DICOM图像数据进行图像变换,最后对变换后的小波系数进行SPIHT编码完成DICOM图像压缩。主客观对图像的评价表明SPIHT算法在高压缩比时仍能保证图像较好的质量。该方法能够对DICOM图像的存储和传输带来便利也将产生一定的影响。     

MIAPS: A web-based system for remotely accessing and presenting medical images

MIAPS (medical image access and presentation system) is a web-based system designed for remotely accessing and presenting DICOM image. MIAPS is accessed with web browser through the Internet. MIAPS provides four features: DICOM image retrieval, maintenance, presentation and output. MIAPS does not intent to replace sophisticated commercial and open source packages, but it provides a web-based solution for teleradiology and medical image sharing. The system has been evaluated by 39 hospitals in China for 10 months.     

面向对象分配带宽的极低比特率视频编码器

在低比特率环境下,如何提高图象编码质量是许多人感兴趣的课题,针对此问题,提出了一种面向对象分配带宽（OOBA）的视频编码器,用以提高低比特率环境下编码图象的主观质量,在充分考虑人的主观视觉特性的基础上,该编码器把图象序列分成不同的视频对象,而每个对象以宏块为单位构成,并且对每个对象单独分配大小不同的带宽,以把更多的比特分配人主观感兴趣的对象,来达到在低比特率环境下提高编码图象主观视觉质量的目的。虽然每个对象独立编码,但在比特流的组织上却能与H．263兼容。为了合理地在多个对象间分配带宽,还给出了基于速率－失真（R－D）模型、基于序列分析和比值加权法等3种带宽分配方法。实验结果表明,该编码器与传统的基于帧的编码器相比,在极低的速率下,峰值信噪比虽略有降低,但图象的视觉质量却得到较大的提高。从而表明了该编码器的有效性,也说明在低比特率环境下,仅以客观准则作为评价编码器好坏的标准是不够的。     

基于Android平台医学图像处理系统

介绍基于DICOM标准的医学图像文件格式和数据元素结构,提出提取DICOM标准的医学图像文本信息和图像数据信息的方法,开发设计基于DICOM标准医学图像在Android平台下显示和处理系统。首先由Android手机从SD卡上获取DICOM图像,通过像素的转换得到Bitmap对象,再显示以及处理图像。该系统实现了DICOM医学图像文件在Android平台上读取、显示以及处理,显示以及处理效果良好,速度快。     

基于LabVIEW的DICOM医学影像处理技术

DICOM是用于医学图像和通信的国际标准,它规定了医疗设备所必须遵循的统一的医学影像文件格式,但DICOM格式的医学图像在Windows平台下无法直接显示。本文首先简要分析了DICOM文件格式,然后给出了在Windows平台下利用LabVIEW显示、存取DICOM图像的实现过程,并利用IMAQ软件包对医学图像进行相应的处理,提高了图像的质量。     

A service based approach for medical image distribution in healthcare Intranets

The Digital Imaging and Communications in Medicine (DICOM) protocol is currently the ubiquitous standard for the communication of medical images and related data within the radiology department. However, seamless image distribution within the healthcare enterprise and especially with research and educational information systems is still hard to achieve, as software developers of such third-party applications have to go through the rather cumbersome task of adapting the DICOM communication model and implementing the DICOM protocol. This paper gives a brief outline of current trends in medical image distribution in the healthcare enterprise, and proposes a new technological approach for distributing DICOM images and related data through commonplace Internet technologies, based on the emerging web services software paradigm. In particular, the paper describes the DICOM Image Management (DIM) web service which acts as a fa?ade for conventional DICOM sources allowing DICOM image data and related information, to be transformed into XML documents encapsulated in SOAP messages, enabling integration at the application level through general purpose standardized web technologies. Implementation issues are discussed and a demonstration of engaging the DIM web service is included.     

Internet上图象渐进传输的研究

在Internet环境中,每个用户所占用的网络带宽是不同的,并且随着网络状况的动态变化而变化,不同用户对图象的质量要求也不一样,因此要求服务器端的图象编码器必须具有高度的适应性。1993年,Shapiro提出的小波零树编码算法是一种非常有效的基于小波变换的图象编码方法,该算法编码器输出的比特流是按基重要性排序的,是对原图象一种渐进的二进制表示。在该算法的基础上,提出了一适合Internet环境下的静态图象渐进传输解决方案,最后给出了实验结果。     

Request redirection paradigm in medical image archive implementation

It is widely recognized that the JPEG2000 facilitates issues in medical imaging: storage, communication, sharing, remote access, interoperability, and presentation scalability. Therefore, JPEG2000 support was added to the DICOM standard Supplement 61. Two approaches to support JPEG2000 medical image are explicitly defined by the DICOM standard: replacing the DICOM image format with corresponding JPEG2000 codestream, or by the Pixel Data Provider service, DICOM supplement 106. The latest one supposes two-step retrieval of medical image: DICOM request and response from a DICOM server, and then JPIP request and response from a JPEG2000 server. We propose a novel strategy for transmission of scalable JPEG2000 images extracted from a single codestream over DICOM network using the DICOM Private Data Element without sacrificing system interoperability. It employs the request redirection paradigm: DICOM request and response from JPEG2000 server through DICOM server. The paper presents programming solution for implementation of request redirection paradigm in a DICOM transparent manner.     

医学图像数据传输与三维可视化系统研究

介绍了医学图像数据传输与三维可视化系统的组成，讨论了与实现系统所具备功能有关的技术细节。借助DICOM3．0标准解决了医学图像数据传输中图像数据的兼容性问题，实现了医学图像的二维处理和三维可视化功能，有利于提高临床诊断的准确性和效率，并实现远程医疗。     

Context based medical image compression for ultrasound images with contextual set partitioning in hierarchical trees algorithm

The basic goal of medical image compression is to reduce the bit rate and enhance the compression efficiency for the transmission and storage of the medical imagery while maintaining an acceptable diagnostic image quality. Because of the storage, transmission bandwidth, picture archiving and communication constraints and the limitations of the conventional compression methods, the medical imagery need to be compressed selectively to reduce the transmission time and storage cost along with the preservance of the high diagnostic quality. The other important reason of context based medical image compression is the high spatial resolution and contrast sensitivity requirements. In medical images, contextual region is an area which contains the most useful and important information and must be coded carefully without appreciable distortion. A novel scheme for context based coding is proposed here and yields significantly better compression rates than the general methods of JPEG and JPEG2K. In this proposed method the contextual part of the image is encoded selectively on the high priority basis with a very low compression rate (high bpp) and the background of the image is separately encoded with a low priority and a high compression rate (low bpp) and they are re-combined for the reconstruction of the image. As a result, high over all compression rates, better diagnostic image quality and improved performance parameters (CR, MSE, PSNR and CoC) are obtained. The experimental results have been compared to the scaling, Maxshift, implicit and EBCOT methods on ultrasound medical images and it is found that the proposed algorithm gives better and improved results.     

DICOM文件头信息读取及解析

DICOM作为医学图像存储和传输的标准,涵盖了医学数字图像的采集、归档、通信、显示及查询等几乎所有信息交换的协议,并且结构化地定义了医疗图像设备制造厂商的兼容性申明.通过分析DICOM文件的构成,解析DICOM文件头的组成和内容,实现对DICOM文件头的信息读取,并利用所获得的信息,进一步读取DICOM文件中的数据集存储内容,是读取DICOM文件的基本解析过程,可以将对DICOM文件的读取,从程序开发商的集成平台中分离出来,在结合图像显示程序之后,作为独立的DICOM文件读取程序使用.     

基于DICOM标准的骨骼三维可视化仿真研究

传统骨骼三维可视化仿真算法对未钙化骨骼不能有效建模.本文以幼儿未钙化肋软骨为对象,通过从DICOM文件中获取图像的相关信息确定三维数据模型,先对该数据进行分类,设定多层阀值,分离出前景数据,再通过从待分割的每个区域中选择一个点作为生长点,搜索特征度满足指定生长准则的像素,并与种子点所在区域合并,实现二度筛选数据,而后采用光影投射法进行体绘制,最后采用高斯平滑进行表面处理.实现了对未钙化的幼儿肋软骨的三维可视化仿真.该方法理论分析与实验结果表明该算法切实可行,有效并易于实现.     

基于PSTN传输信道的视频编码器码率控制

码率控制是在低带宽信道上传输低延迟、高质量视频的关键技术之一．根据基于PSTN信道的远程视频监控应用需求，提出一种甚低码率控制策略，通过为视频编码器增加Ⅰ帧码率控制，改进P帧的位率控制算法，以及引入二阶率失真模型，较好地解决了甚低带宽下视频编码器的码率控制问题．实验结果表明，算法降低了编码缓冲区延迟同时提高了重建图像的质量。     

Implementation of a dynamic platform-independent DICOM-server

Hospital-wide image and patient data transfer within heterogeneous hard- and software infrastructures can be facilitated by using standardized communication protocols and data formats such as digital imaging and communications in medicine (DICOM). Each DICOM application entity (AE) usually provides a static and fixed set of services according to its functionality. However, certain security concepts, changing demands of medical users, or restricted hardware capabilities may be more easily addressed by applications that dynamically provide variable subsets of DICOM services. In a new approach, an object-oriented DICOM server framework was developed that served as a basis for assembling various DICOM applications. These applications may be set up dynamically to offer variable subsets of services at runtime, similar to "plug-ins". The framework was designed and implemented in Java in order to provide low-cost platform-independent solutions. As an example, a DICOM server was implemented and tested in a clinical application providing access to MR and CT images through a Java/DICOM viewer. Data retrieval was optimized by storing parts of the image acquisition and patient data into a relational database.     

Diagnostic accuracy of a teleradiology image transmission system

Teleradiology is the remote interpretation of digitized radiographic images by physicians. The images are usually transmitted over telephone lines, but satellite communication has also been used. The interpretability of the transmitted image is an important factor in the operation and use of teleradiology systems. Commercially available equipment has certain built-in functions that may enhance the interpretability of the image received. These functions and their usefulness in diagnosis are described. It is also possible to enhance the image for transmission, prior to digitizing, by certain manual techniques. These may be of value in situations where the first transmission is lacking in some quality. A test of these functions and techniques is reported.     

Study on the technology of medical image reading based on JPEG2000

Along with the development of health informatization, many hospitals have set up PACS systems for centralized storage of patients’ medical examination images. Due to the large amount of image data, traditional methods such as C-MOVE, have slow upload and download speeds. And they also have security problems. Based on the research and development of medical imaging informatics and PACS, a JPEG2000-based method is described according to the PACS work flow and DICOM standard. This method makes the image storage, transmission and display operating in parallel, providing a good solution to timeliness and security problems of image reading and viewing.     

A lossless data hiding scheme for medical images using a hybrid solution based on IBRW error histogram computation and quartered interpolation with greedy weights

In the digital world, watermarking technology is a solution for data hiding and completely essential for management and secure communications of digital data propagated over the internet-based platforms. Reversible watermarking is a quality-aware type of watermarking which has been applied in managing digital contents such as digital images, texts, audios and videos. Reversible watermarking is also known as lossless watermarking due to its preservation of all details of host and hidden data. One of the important uses of this kind of watermarking is to manage medical data regarding DICOM images. In the recent years, a new type of reversible watermarking technology entitled interpolation-based reversible watermarking has been introduced, and we are going to enhance it for DICOM images by using a hybrid approach based on computing error histogram and by applying an image interpolation with greedy weights (adaptive weighting). In practice, simulation results clearly show better performance of the proposed scheme compared to the previous techniques using interpolation-based reversible watermarking on different DICOM images.

     

医学影像多尺度压缩传输方法的研究

医学影像数字化后需要的存储量很大且要求的精确度高,为了保证医学影像的使用质量,现在的医学影像在传输时常需采用无损压缩。但是,这样的医学影像传输方法会占用相当大的带宽,也大大降低了传输速度。提出一种对医学影像的感兴趣区域和非感兴趣区域进行多尺度压缩的方法实现有损压缩传输,获得了良好的效果,并且把实验结果与其他方法进行了对比,结果表明该方法可以有效提高压缩率,提高传输速率。     

基于OpenGL的DICOM医学图像读取和显示

DICOM 3.0是医院各影像设备所遵循的标准,该标准的文件一般不被现有的图像处理软件所支持.通过对医学数字成像和通信(DICOM)标准的研究,编写了DICOM文件的读取与显示程序,使得普通电脑也可以显示DICOM标准的医疗影像图片.为医疗影像的三维重建、医生对病灶处的诊断以及模拟手术的实施提供了前期技术支持,有助于医学资源的共享.     

控制图象灰度失真的高保真压缩算法

为实现遥感图象的高保真压缩 ,在借鉴 JPEG- L S近无损压缩思想的基础上 ,提出了 3项改进措施 ,设计与实现了比 JPEG- L S压缩倍数高、图象恢复质量更好的视觉无失真压缩算法——“控制图象灰度失真的高保真压缩算法 (L IGE)”.实验结果表明 ,该算法既可限制图象最大灰度误差 ,又能控制恢复图象的峰值信噪比 ,从而有效地控制图象失真度 ,压缩倍数为 4时 ,数据处理速度与图象恢复质量两方面 ,均优于基于小波变换和嵌入式零树编码的 SPIHT算法 .该研究成果将对发展我国未来的高分辨率卫星、小卫星通信系统、星 -天 -地信息网提供有力的技术支撑 .