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101.
超分辨率图像重建中,Huber马尔可夫随机场模型是一种常用的正则化算子.针对Huber函数中固定梯度阈值引起图像重建效果不佳的问题,本文提出一种梯度阈值自适应处理的红外图像超分辨率重建算法.在最大后验概率理论框架下,构造了基于数据项和正则项的正则化模型;通过迭代的方式,利用中间重建结果不断更新正则化参量,解决了Huber马尔可夫随机场模型中梯度阈值不易选择的难题.实验结果表明,改进算法能够根据局部梯度特征自适应选择相应的正则化参量并找到最优解,较好恢复目标细节的同时有效抑制了图像噪音. 相似文献
102.
103.
SUN Yi-Fan 《理论物理通讯》2012,57(6):1095-1100
Compressed sensing is a new signal acquisition method that acquires signal in a compressed form and then recovers the signal by the use of computational tools and techniques. This means fewer measurements of signal are needed and thus it will save huge amount of time and storage space. We, in this paper, consider the compressed sensing of sparse integer-valued signal (referred as “q-states signal” throughout the paper). In order to accelerate the speed of reconstruction, we adopt the sparse rather than dense measurement matrices. Using methods and tools developed in statistical physics, we locate the reconstruction limit for L0-reconstruction method and propose a belief propagation-based algorithm that can deal with instance with large size and its typical reconstruction performance are also analyzed. 相似文献
104.
We present a digital holography microscopy technique based on a parallel-quadrature phase-shifting method. Two π/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography. 相似文献
105.
金属材料在冲击载荷下的动态响应在许多民用工程、航空航天等领域都有重要的应用背景.而金属材料在冲击载荷下的微喷形成过程,包括微射流、碎裂以及微层裂的物理过程的研究中尚存在许多空白.介绍了国内首次在神光Ⅲ原型激光装置上开展的金属材料微喷回收实验,实现了激光加载下低密度泡沫材料对微喷颗粒的回收,对回收样品进行了X光CT分析,通过图像重建,获得了回收微喷颗粒的三维图像,以及颗粒不同形态分布、颗粒尺寸、颗粒质量等定量结果. 相似文献
106.
在基于结构光照明的三维面形测量中,针对有孤立区域物体的条纹图像存在不规则缺陷的问题,提出先对其进行Gerchberg迭代,消除或减少条纹缺陷,获取较完善的迭代条纹,然后再利用傅里叶变换轮廓术(FTP)重建面形。设计了迭代流程,并分析了影响迭代精度的因素,解决了光学加工用具磨盘表面不完善条纹Gerchberg迭代过程中存在的问题,成功地重建了磨盘的三维面形。该工作为表面存在孤立区域的被测物体三维面形测量提供了可供参考的技术方案,也给可实时形变的应力盘三维面形动态测量奠定了基础。 相似文献
107.
108.
Compton scattering imaging is a novel radiation imaging method using scattered photons.Its main characteristics are detectors that do not have to be on the opposite side of the source,so avoiding the rotation process.The reconstruction problem of Compton scattering imaging is the inverse problem to solve electron densities from nonlinear equations,which is ill-posed.This means the solution exhibits instability and sensitivity to noise or erroneous measurements.Using the theory for reconstruction of sparse images,a reconstruction algorithm based on total variation minimization is proposed.The reconstruction problem is described as an optimization problem with nonlinear data-consistency constraint.The simulated results show that the proposed algorithm could reduce reconstruction error and improve image quality,especially when there are not enough measurements. 相似文献
109.
To study the spectrum reconstruction of the 20 MV X-ray generated by the Dragon-I linear induction accelerator, the Monte Carlo method is applied to simulate the attenuations of the X-ray in the attenuators of different thicknesses and thus provide the transmission data. As is known, the spectrum estimation from transmission data is an ill-conditioned problem. The method based on iterative perturbations is employed to derive the X-ray spectra, where initial guesses are used to start the process. This algorithm takes into account not only the minimization of the differences between the measured and the calculated transmissions but also the smoothness feature of the spectrum function. In this work, various filter materials are put to use as the attenuator, and the condition for an accurate and robust solution of the X-ray spectrum calculation is demonstrated. The influences of the scattering photons within different intervals of emergence angle on the X-ray spectrum reconstruction are also analyzed. 相似文献
110.