Large aperture static interferential multispectral image compression with motion compensation and region of interest coding

To perform better on interferential multispectral image compression, wavelet transform based on motion compensation and region of interest coding and asymmetric zerotree was proposed. According to the movement in the images and the characters of spectrum, the motion compensation and raising coefficients of intensive interference area were used in this wavelet. In this way, the relativity among the spectra is reduced and the intensive interference area coefficients can be coded preferentially. The asymmetric zerotree was proposed due to the unsymmetrical structure of images formed by the wavelet. Experimental results show that with eightfold compression, this algorithm outperforms the three-dimensional set partitioning in hierarchical trees (3DSPIHT) in the range of 0.35–0.49 dB in power signal-to-noise ratio (PSNR) and outperforms the 2DSPIHT in the range of 2.24–2.62 dB in PSNR. Compared to joint picture expert group 2000 (JPEG2000) upscaling method, the effect of intensive interference area is also improved 0.29–0.38 dB in PSNR. Meanwhile, the average of mean square error of spectra within 46 spectrum bands is reduced to 9.69. Translated from Journal of Xi’an Jiaotong University, 2006, 40(4):449–453 [译自: 西安交通大学学报]     

星载SAR对舰船高分辨成像研究

研究了星载SAR对舰船高分辨成像的难度和方法。在星载SAR舰船数据获取模型的基础上，着重分析了舰船航行以及船体在特定海情时三维转动对星载SAR成像的影响，研究了星载SAR舰船数据的ISAR成像方法，并给出成像算法流程，仿真结果验证了该方法的有效性。     

摄像机标定方法综述

首先介绍了摄像机标定的基本原理以及对摄像机标定方法的分类。通过对最优化标定法、双平面标定法、两步法等传统摄像机方法的具体分析，给出了各种方法的优劣对比；同时对多种自标定方法的研究现状、发展情况以及存在问题进行了探讨。最后给出了发展传统摄像机标定方向、提高摄像机自标定精度的二些参考建议。     

对合成孔径雷达的随机移频干扰

本文分析了传统移频干扰对合成孔径雷达(SAR)的干扰效果,针对固定移频干扰只能形成点目标或线目标干扰的局限,提出了一种改进的移频干扰新样式——随机移频干扰。理论分析表明脉间去相关的随机移频干扰经SAR距离向和方位向处理,成像输出为距离上占据一定宽度的似噪条带,可用于压制分布目标,克服了固定移频干扰的局限。文中实验部分比较了脉间去相关随机移频干扰和现有的SAR压制干扰样式——噪声干扰和距离调频率脉间去相干干扰的干扰性能,验证了该干扰的有效性。     

星载分布式SAR干涉信号分析

星载分布式合成孔径雷达(SAR)具有双站和斜视的特点,本文分析了在这种情况下干涉信号的一些特征:(1)干涉信号相位与成像处理间的关系;(2)考虑地形情况下,干涉信号相位差及其相干性;(3)考虑配准误差时干涉信号相位差及其相干性。仿真分析了一系统干涉信号相干性随地形、基线及配准误差的变化。     

A hybrid PET‐MRI: An integrated molecular‐genetic imaging system with HRRT‐PET and 7.0‐T MRI

A PET‐MRI fusion system is developed for molecular‐genetic imaging. The purpose of the system is to obtain images of the in‐vivo human brain using two high‐end imaging devices, an advanced PET and an ultrahigh‐field MRI. These are the HRRT‐PET, a high‐resolution research tomograph dedicated to brain imaging on the molecular level, and the 7.0‐T MRI, an ultrahigh field version used for morphological imaging. HRRT‐PET delivers high‐resolution molecular imaging with a resolution down to 2.5 mm FWHM, which is currently the highest spatial resolution available for the observation of the human brain's molecular activities, including enzymes and receptors, which are manipulated genetically, such as reporter genes and probes. The 7.0‐T MRI began to reveal submillimeter resolution images of the cortical as well as deep brain areas, down to 250 μm, which allows us to visualize the fine details of the cortical and brainstem areas, including the line of Gennari in the visual cortex and the corticospinal tracts in the pontine area. The current PET‐MRI fusion imaging system produces the highest quality images of molecular and genetic activities of the human brain in vivo. It is starting to provide many answers to the key questions about the neurological diseases. Some of these start providing answers to many cognitive neuroscience problems with clear molecular and genetic bases. There is great potential in the PET‐MRI for early diagnosis of cancers as well as other neurological diseases, which we were previously unable to diagnose, such as microscopic molecular changes that occur in Parkinson's and Alzheimer's diseases. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 252–265, 2007     

基于DRFM的SAR干扰技术研究

本文从DRFM的时钟分析出发,研究了DRFM的A/D、D/A时钟差异对输出信号的影响,并以此为基础研究了DRFM输出信号对SAR进行干扰所带来的影响,研究了A/D、D/A时钟的差异与干扰模式和干扰效果的关系,最后通过仿真对前文的分析进行了验证。     

基于微焦斑源X射线传播的相衬成像模拟

从标量衍射及部分相干光衍射理论出发,结合硬X射线特点,建立基于微焦斑X射线源的衍射成像模型.该模型将Fresnel积分运算转换到空间频域,利用快速傅里叶变换计算衍射光场.根据部分相干光理论分析,有限大小光源的物体衍射光场为光源光强分布与点源所形成的物体衍射光场的卷积,将卷积运算转换到空间频域并利用快速傅里叶变换算法提高运算速度.模拟衍射结果表明,物体到X射线源的距离、X射线光子能量以及X射线源焦斑尺寸均影响自由空间传播相衬成像系统的图像衬度.研究结果有助于X射线相衬成像系统的设计和性能优化.