A color correction algorithm for noisy multi-view images

A novel color correction algorithm for noisy multi-view images is presented. The key idea is to use the improved Karhunen-Loeve (K-L) transform to obtain correction matrix that can eliminate noise effect to the fullest extent. Noise variance estimation is first performed in the algorithm. In the end, wavelet transform is applied to denoise the corrected image. Experimental results show that, compared with traditional correction method, a well-performed correction result is achieved using the proposed method,and the visual effect of the denoised corrected image is almost consistent with ideal corrected image.     

Dominant color extraction based color correction for multi-view images

Color information is very important in setting the style of images. In this paper, a color correction method based on dominant color extraction is proposed to eliminate the color inconsistence between multi-view images. With the theory of basic color categories, dominant colors from the categories are extracted for reference image and input image, and then the corresponding color mapping relationships are built.Experimental results show that the proposed method is quite effective.     

Elimination of zero-order and conjugate images in off-axis digital holography

In this paper, a new digital method has been developed for eliminating the zero-order and conjugate image in off-axis digital holography. The method consists of filtering the spatial frequencies associated with these undesired terms (the zero-order and conjugate images) in the computed Fourier transform plane of the hologram multiplied with computer simulated original reference wave (written as (RI_h)). An important conclusion is that, without the need for additional shift-spectrum process, the spectrum of real image always appears in the center of the spectrum plane and never shifts. This brings us some convenient to design a filtering window. The theoretical analysis and the corresponding simulation and experiment results are given. As the zero-order and conjugate image are eliminated, both the contrast and brightness of the real image are enhanced and the image quality is improved. Meanwhile, the process of designing a filtering window is simple and convenient.     

Acoustic quasi-holographic images of scattering by vertical cylinders from one-dimensional bistatic scans

When synthetic aperture sonar (SAS) is used to image elastic targets in water, subtle features can be present in the images associated with the dynamical response of the target being viewed. In an effort to improve the understanding of such responses, as well as to explore alternative image processing methods, a laboratory-based system was developed in which targets were illuminated by a transient acoustic source, and bistatic responses were recorded by scanning a hydrophone along a rail system. Images were constructed using a relatively conventional bistatic SAS algorithm and were compared with images based on supersonic holography. The holographic method is a simplification of one previously used to view the time evolution of a target's response [Hefner and Marston, ARLO 2, 55-60 (2001)]. In the holographic method, the space-time evolution of the scattering was used to construct a two-dimensional image with cross range and time as coordinates. Various features for vertically hung cylindrical targets were interpreted using high frequency ray theory. This includes contributions from guided surface elastic waves, as well as transmitted-wave features and specular reflection.     

双目智能眼镜视差快速测试系统设计

为了快速测试双目智能眼镜的视差,提出了一种用大口径长焦距镜头CMOS作为检测设备的测试系统。将大口径长焦距镜头的CMOS相机与双目智能眼镜的光轴在同一水平面上且共线,通过一次拍摄得到双目智能眼镜的显示画面,借助十字刻度测试图作为图像源,快速计算出双目智能眼镜的视差。论述并推导了双目智能眼镜视差产生的数学模型及计算公式,分析了系统误差来源。实验结果表明,一次拍摄就可以得到表征双目视差的图像;相机图像采集精度误差为2.47″;测试图读数误差为3.7′;测试图读数测试法与实际测试结果的误差为3.85′,满足快速高效测试双目智能眼镜的要求。     

基于视差自相关特征水深反演

提出了一种基于视差自相关特征模拟水深的新方法。这种方法利用不同摄站获取的同一物体的两幅图像,在水的折射影响下,造成的视觉上的偏差计算水深,可以得到相关区域三维显示中各点的水深数值。以数码相机所拍摄两张照片为例,实现相关区域水深三维显示。结果表明此算法具有一定的可行性,可以进行更深层次的研究,并应用于浅海、河流等地的资源探测开发。     

Crosstalk reduction in multi-view autostereoscopic three-dimensional display based on lenticular sheet

A method to reduce crosstalk in multi-view autostereoscopic three-dimensional (3D) displays based on the lenticular sheet is proposed. Correcting the luminance values of each parallax image displayed on the display screen is employed. We analyze the causes of crosstalk. We deduce the formulas of crosstalk reduction according to the relationship between crosstalk coefficients of each parallax image observed through the lenticular sheet, luminance values of each parallax image displayed on the display screen,...     

交叉视差及观看时间对自由立体显示视觉舒适度的影响

针对自由立体显示器视疲劳的问题,对交叉视差及观看时间影响视觉舒适度的问题进行了分析和研究。实验选取具有交叉视差的图片和视频,观察者采用主观评价和客观评价相结合的方法,对其观看舒适度进行评价。结果表明具有交叉视差的图片和视频,其观看舒适度都随时间的增加而减弱,图片的观看时间应在23min以内,视频的观看时间应在17min以内,此时观看较为舒适。持续观看具有交叉视差的图片和视频会引起视疲劳,应控制其观看时间。     

Horizontal parallax distortion in toed-in camera with wide-angle lens for mobile device

An effect of the toed-in camera configuration is keystone distortion, which causes vertical and horizontal parallax in the stereoscopic image. The horizontal parallax is the source of the depth plane curvature. However, if the stereoscopic image captured by the toed-in camera system with fish-eye lens is displayed on mobile device, it is uncomfortable to view because the horizontal parallax contains horizontal parallax distortion occurred by the wide field of view of the lenses. Therefore, in this paper, we propose a novel correction method of the horizontal parallax distortion, which is one of the keystone distortions, in a toed-in camera with fish-eye lenses for mobile device. We have experimented to attest the proposed method. In experiment, we used two charge coupled device cameras, whose field of view is 48.48°. In addition, the captured stereoscopic image was corrected for the barrel distortion and the horizontal parallax distortion. Therefore, the proposed method provides correcting of the horizontal parallax distortion from a toed-in camera system in order that the users can enjoy three-dimensional effects without the visual fatigue. Additionally, the proposed method is able to apply to toed-in camera consisting of any kinds of cameras.     

基于多重结构的平显视差仪中内调焦物镜设计

根据平显视差测量原理中自动调焦的要求,设计了一个相对孔径与调焦范围均较大的内调焦物镜。针对内调焦传统设计方法的不足,在对内调焦各镜组选型后将它们组合成为一个系统,采用多重数据结构设计的方法,对不同物距下的结构进行同时优化,从而解决了近距离的成像质量难以控制的问题。所设计的内调焦物镜在不同的物距下成像质量稳定,无穷远时光学传递函数(MTF)值在空间频率为120 lp/mm时轴上与轴外均达到0.4以上,物距在300 mm时轴上视场MTF为0.3,轴外视场弧矢MTF在0.3以上,子午MTF达到了0.2;相对畸变均控制在1%以内,有利于后续的图像处理工作。     

Elimination of fast variables

First nonlinear ordinary differential equations for the evolution of a physical system are considered. When they involved a small (or large) parameter the evolution occurs on two time scales. A general scheme is developed for extracting equations for the slow evolution, including higher order corrections. The scheme unifies the multifarious methods that exist in the literature. It leads to a subdivision in three categories, determined by the structure of the equations.Although linear equations are merely a specialization, they can readily be generalized to the case of linear partial differential equations, such as the so amply studied Fokker-Planck equation. These are treated with special attention to the definition of the required projection operator.Throughout, numerous examples and applications are given.     

Position determination and strong field parallax effects for photon emitters in the Schwarzschild spacetime

Position determination of photon emitters and associated strong field parallax effects are investigated using relativistic optics when the photon orbits are confined to the equatorial plane of the Schwarzschild spacetime. We assume the emitter is at a fixed space position and the receiver moves along a circular geodesic orbit. This study requires solving the inverse problem of determining the (spatial) intersection point of two null geodesic initial data problems, serving as a simplified model for applications in relativistic astrometry as well as in radar and satellite communications.     

Effect of thickness of parallax barrier on viewing angle of one-dimensional integral imaging display

A parameter design of a parallax barrier is one of the most important keys to design a one-dimensional integral imaging (1DII) display using parallax barrier. The relationship between the thickness of the parallax barrier and the viewing angle of the 1DII display is studied, and the maximal value of the thickness is also obtained. When the thickness of the parallax barrier is greater than the maximal value, the viewing angle of the 1DII display is decreased with increasing the thickness of the parallax barrier. A prototype of the 1DII display using parallax barrier is developed, and the experimental results agree well with the theory.     

Elimination of cross talk in waveguide intersections

We present general criteria for crossing perpendicular waveguides with nearly 100% throughput and 0% cross talk. Our design applies even when the waveguide width is of the order of the wavelength. The theoretical basis for this phenomenon is explained in terms of symmetry considerations and resonant tunneling and is then illustrated with numerical simulations for both a two-dimensional photonic crystal and a conventional high-index-contrast waveguide crossing. Cross-talk reduction by up to 8 orders of magnitude is achieved relative to unmodified crossings.     

Elimination of vortex streets in bluff-body flows

We present an effective technique for suppressing the vortex-induced vibrations of bluff bodies by eliminating the von Kármán street formed in their wake. Specifically, we find that small amounts of combined windward suction and leeward blowing around the body modify the wake instability and lead to suppression of the fluctuating lift force. Three-dimensional simulations and stability analysis are employed to quantify our findings for the flow past fixed and flexibly mounted circular cylinders.     

Elimination of variables in simple laser equations

The usual way of obtaining rate equations (RE) and a single equation for the field amplitude (EFA) from the semiclassical laser equations (Lorenz-Haken model) is reexamined by undertaking a systematic elimination procedure developed in synergetics. The RE and EFA are justified in the case 1 (, ) and case 2 (, ), respectively. We show that, because the eliminated variable happens to contain a considerable contribution from an unstable mode, the usual elimination technique in the case 3 (, ) leads to an inconsistency. As important by-products we obtain the RE and EFA for arbitrary cavity relaxation constant (). Some remarks are given on the direct elimination technique in the non-diagonal representation in the study of instabilities.     

Elimination of crosstalk in directional coupler switches

We propose a tapered electrode structure to make the ratio of the coupling coefficient to the difference of propagation constants between two coupled waveguides in a directional coupler switch a constant throughout it. In this way, the crosstalk caused by the existence of tapered sections is entirely eliminated.     

Adiabatic Elimination in Quantum Stochastic Models

We consider a physical system with a coupling to bosonic reservoirs via a quantum stochastic differential equation. We study the limit of this model as the coupling strength tends to infinity. We show that in this limit the solution to the quantum stochastic differential equation converges strongly to the solution of a limit quantum stochastic differential equation. In the limiting dynamics the excited states are removed and the ground states couple directly to the reservoirs.