Omnistereo: panoramic stereo imaging

An omnistereo panorama consists of a pair of panoramic images, where one panorama is for the left eye and another panorama is for the right eye. The panoramic stereo pair provides a stereo sensation up to a full 360 degrees. Omnistereo panoramas can be constructed by mosaicing images from a single rotating camera. This approach also enables the control of stereo disparity, giving larger baselines for faraway scenes, and a smaller baseline for closer scenes. Capturing panoramic omnistereo images with a rotating camera makes it impossible to capture dynamic scenes at video rates and limits omnistereo imaging to stationary scenes. We present two possibilities for capturing omnistereo panoramas using optics without any moving parts. A special mirror is introduced such that viewing the scene through this mirror creates the same rays as those used with the rotating cameras. The lens used for omnistereo panorama is also introduced, together with the design of the mirror. Omnistereo panoramas can also be rendered by computer graphics methods to represent virtual environments     

Motion artifacts observed in 3‐D LCDs that use shutter glasses (SG 3D)

Abstract— Motion artifacts observed in 3‐D LCDs using shutter glasses (SG 3D) has been investigated. A ghost‐like artifact has been observed for static images due to incomplete image separation between the left and right views. The observed motion artifacts are different for the left and right views. And they occur even for images with zero binocular disparity. In this respect, the phenomena of observed artifacts in 3‐D moving images are differentfrom those of 3‐D static images. 3‐D motion artifacts were analyzed and are related to the moving speed of the images and the amount of binocular disparity.     

基于方向经验模型分解的纹理合成

提出的纹理合成算法首先将样本纹理通过方向经验模型分解求得其固有方向;然后在该方向上进行方向经验模型分解,获得一系列分解图像;在各级图像上应用方向经验模型分解提取出的特征值来搜索匹配块,采用相关搜索来完成各级图像的合成;将其进行合并,得到在该方向上的合成图像;最后沿固有方向进行逆旋转变换,得到最终的合成结果.实验结果表明,该算法不仅合成质量高,而且简单、快速.     

Modeling and compensation of dynamic effects in camera-based position measurement

Cameras are used as position sensors for camera-based control or metrology, the goal being to estimate the position of some markers or features. When one of these markers has significant displacement over the exposure time, the measurement delivered by image processing cannot be considered as a sample of the actual trajectory as dynamic effects become effective. In this paper, models are proposed that allow to reproduce accurately the measurements provided by a camera. Various cases are considered: with full or partial exposure time; with global shutter mode or rolling shutter mode. An experimental evaluation in the global shutter case shows the accuracies of the models.When the continuous-time trajectory of a device needs to be reconstructed, these accurate models of the camera-based position measurement can be used in order to improve the trajectory provided by the camera. A methodology based on a hybrid Kalman filter is proposed to solve this general issue. An experimental evaluation is provided for the global shutter case, based on real images inspired from the problem of heart motion reconstruction.     

Forget the funny glasses [autostereoscopic display systems]

Shutter glasses, polarized glasses, and head-mounted displays (HMDs) have become common technologies for providing the illusion of 3D. Shutter glasses, popularized by StereoGraphics as CrystalEyes, use an LCD shutter over each eye to enable stereo viewing. The shutters are rendered alternately opaque and transparent so that only one eye can see through the glasses at any moment. The glasses are synchronized to the display system presenting the right and left images at the same frequency as the shutters' phase shifts. These systems can work with televisions, computer monitors, or projectors, but require that the display system can generate images at twice the frequency desired for viewing, because each frame must be shown twice (once for each eye). Although they can cause some loss of image brightness and can suffer from crosstalk, shutter glasses work well and permit full-spectrum color. However, especially with low-cost systems, they can cause eyestrain and other discomfort. In addition, the eyewear is bulky and often heavy, which makes using shutter glasses for long periods of time somewhat uncomfortable. Autostereoscopic displays (ASDs) use several technologies to present different images to both of a viewer's eyes. Volumetric display systems (VDSs) create an image with true depth, letting the eyes and brainwork in natural manner. ASD and VDS systems are intended to replace current 3D displays, all of which require the user to wear some sort of filtering system, such as eyeglasses.     

Super-resolution in practice: the complete pipeline from image capture to super-resolved subimage creation using a novel frame selection method

We present a complete super-resolution system using a camera, that is assumed to be on a vibrating platform and continually capturing frames of a static scene, that have to be super-resolved in particular regions of interest. In a practical system the shutter of the camera is not synchronised with the vibrations it is subjected to. So, we propose a novel method for frame selection according to their degree of blurring and we combine a tracker with the sequence of selected frames to identify the subimages containing the region of interest. The extracted subimages are subsequently co-registered using a state of the art sub-pixel registration algorithm. Further selection of the co-registered subimages takes place, according to the confidence in the registration result. Finally, the subimage of interest is super-resolved using a state of the art super-resolution algorithm. The proposed frame selection method is of generic applicability and it is validated with the help of manual frame quality assessment.     

An open and shut case [computer graphics]

You press the button on your camera, the shutter opens, the film is exposed, the shutter closes, and you have a picture. If anything moved, including you, the image will show motion blur. When we create synthetic images with computer graphics, we have to account for motion blur for three reasons. First, we're used to it from physical motion pictures. Second, without motion blur a film can suffer from strobing, a psychophysical phenomenon. Third, without motion blur an object can alias in time. In a real camera, a mechanical device called the shutter controls the exposure of the film. The computer graphics literature includes many camera models, lenses, and even discussions of film and its simulation. Surprisingly, there is little discussion of simulating how a moving shutter actually exposes the film. The author finds it surprising because modeling the shutter mechanism is easy, and as shown in the article, very important to the rendered image. The following shutter types are modelled via computer graphics: instantaneous shutter; uniform shutter; focal plane shutter; interlaced shutter; leaf shutter; inverse leaf shutter; and clock shutter     

Angular dependence of the performance of stereoscopic liquid‐crystal‐display (LCD) television using shutter glasses (SG)

Abstract— 3‐D cross‐talk typically represents the ratio of image overlap between the left and right views. For stereoscopic LCDs using shutter‐glasses technology, 3‐D cross‐talk for stereoscopic LCD TV with a diagonal size of 46 in. and vertical alignment (VA) mode was measured to change from 1% to 10% when the stereoscopic display is rotated around the vertical axis. Input signals consist of the left and right images that include patterns of different amounts of binocular disparity and various gray levels. Ghost‐like artifacts are observed. Furthermore, intensities of these artifacts are observed to change as the stereoscopic display is rotated about the vertical axis. The temporal luminance of the LCD used in stereoscopic TV was found to be dependent on the viewing direction and can be considered as one cause of the phenomenon of angular dependence of performance for stereoscopic displays.     

High‐resolution autostereoscopic 3‐D projection display with a space‐dividing iris‐plane shutter

Abstract— A high‐resolution autostereoscopic 3‐D projection display with a polarization‐control space dividing the iris‐plane liquid‐crystal shutter is proposed. The polarization‐control iris‐plane shutter can control the direction of stereo images without reducing the image quality of the microdis‐play. This autostereoscopic 3‐D projection display is 2‐D/3‐D switchable and has a high resolution and high luminance. In addition, it has no cross‐talk between the left and right viewing zones, a simple structure, and the capability to show multi‐view images.     

Fourth-Order Semi-Compact Scheme for Flow Past a Rotating and Translating Cylinder

In the present investigation, the newly developed Higher Order Semi-Compact (HOSC) finite difference scheme has been tested for its capability in capturing the very complex flow phenomenon of unsteady flow past a rotating and translating circular cylinder. The physical problem has been modeled in stream function and vorticity formulation and the obtained governing equations are transformed into curvilinear coordinates using body fitted coordinate system to enable the developed scheme to handle the non-rectangular geometry of the problem. Qualitative and quantitative comparisons have been done at low-rotation parameters and found that the results obtained are in excellent agreement with the existing literature. Then simulations have been carried out at high-rotation parameters and noticed that the HOSC scheme is able to simulate some of the flow features known experimentally but not simulated numerically to the present date.     

基于跨接约束的高分辨率SAR 影像与光学影像配准

为了实现高分辨率SAR 影像与光学影像之间自动/半自动配准, 提出了一种新颖、稳健的匹配算法。算法首先利用仿射变换进行SAR 影像和光学影像粗匹配, 简化了整体算法的处理复杂度;然后利用影像边缘稳健性, 使用边缘提取算子分别对SAR 影像和光学影像进行边缘提取, 为后续精匹配做好了数据准备; 最后使用基于边缘纹理跨接约束进行影像之间精匹配, 方法引入了邻域配准约束机制, 很好的解决了经典匹配多峰值效应, 提高了算法稳健性和实用性。以国内机载高分辨率SAR 数据和SPOT 25 PAN 数据为例进行算法验证, 实验结果表明该算法能实现自动/半自动的高分辨率SAR 和光学影像之间的像素级配准。     

车载无人机的多路影像采集与拼接

为提高无人机(UAV)采集全景影像的效率,采用基于ARM内核的高性能影像编解码处理器,以Linux为操作系统,搭载多路影像传感器,构建了一种适合无人机平台的多路影像同步采集的嵌入式系统.设计了软件多线程同步采集模式及基于Qt与OpenCV视觉库的多影像拼接界面,实现了全景影像的多角度实时同步获取及多路影像的拼接.系统软硬件联调与实验结果表明:该系统能成功完成多路影像数据的同步采集拼接处理,操作方便,达到了预期的要求和效果.     

一种应用于高动态范围CMOS图像传感器的曝光控制技术

本文针对提高CMOS图像传感器的动态范围,提出了一种新的组合滚筒式曝光技术。由目前现有的技术可知,多次滚筒式曝光一般选择在单帧的时间周期内完成。根据不同的曝光参数,CMOS图像传感器芯片输出不同的图像,然后再将其组合成一帧宽动态范围的图像作为最后输出。本文提出的方法,通过充分利用滚筒式曝光时的空闲电路资源,有效地缩短了相邻图像间的时间间隔。这种方法将多次滚筒式曝光穿插进行,实现对目标图像的多次成像,从而有效提高了系统效率和输出响应速度。     

Attenuation of rotating disk vibrations with sector-shaped plates in disk storage devices

A parametric study has been conducted to understand the mass loading contribution to rotating disk vibrations in disk storage devices. With sector-shaped plates retaining air between the two plates and a rotating disk, results have shown frequency crossing of disk flutter modes with non-zero nodal diameters where significant modal pattern switching is observed. Extending the range of the analysis to sector geometries provides insight into the disk vibrations on the degree of frequency separation and mode switching as a span angle of the sector-shaped plates and disk rotating speed. Design guidelines are formulated to minimize this mode crossing phenomenon and thus minimize the number of spindle disturbances present during track follow or the servotrack writing process.     

Underwater image enhancement using blending of CLAHE and percentile methodologies

In this paper, a method has been proposed for enhancement of underwater images commonly suffering from low contrast and degraded shading quality. The entirety of the image is changed when we move to capture of images, from air to the water. During capturing some absorption, reflection and scattering effects are induced in the form of contrast, quality and noise as the images look hazy or blurred. This makes one shading to overwhelm the image. For use of underwater resources and overcome these factors the enhancement of the images is required. So, in this paper, we proposed a strategy for underwater image enhancement using Contrast-Limited Adaptive Histogram Equalization (CLAHE) and Percentile methodologies. Finally, these two methodologies are blended for improving the outcomes. Two parameters, namely, Root Mean Squared Error (RMSE) and entropy have been considered for comparing the experimental results of the proposed methodology with the state-of-the-art works. It has been noticed that the proposed system performs better than already existing techniques for underwater image enhancement.     

Single‐shot High Dynamic Range Imaging Using Coded Electronic Shutter

Typical high dynamic range (HDR) imaging approaches based on multiple images have difficulties in handling moving objects and camera shakes, suffering from the ghosting effect and the loss of sharpness in the output HDR image. While there exist a variety of solutions for resolving such limitations, most of the existing algorithms are susceptible to complex motions, saturation, and occlusions. In this paper, we propose an HDR imaging approach using the coded electronic shutter which can capture a scene with row‐wise varying exposures in a single image. Our approach enables a direct extension of the dynamic range of the captured image without using multiple images, by photometrically calibrating rows with different exposures. Due to the concurrent capture of multiple exposures, misalignments of moving objects are naturally avoided with significant reduction in the ghosting effect. To handle the issues with under‐/over‐exposure, noise, and blurs, we present a coherent HDR imaging process where the problems are resolved one by one at each step. Experimental results with real photographs, captured using a coded electronic shutter, demonstrate that our method produces a high quality HDR images without the ghosting and blur artifacts.     

Image motion estimation from motion smear-a new computational model

Motion smear is an important visual cue for motion perception by the human vision system (HVS). However, in image analysis research, exploiting motion smear has been largely ignored. Rather, motion smear is usually considered as a degradation of images that needs to be removed. In this paper, the authors establish a computational model that estimates image motion from motion smear information-“motion from smear”. In many real situations, the shutter of the sensing camera must be kept open long enough to produce images of adequate signal-to-noise ratio (SNR), resulting in significant motion smear in images. The authors present a new motion blur model and an algorithm that enables unique estimation of image motion. A prototype sensor system that exploits the new motion blur model has been built to acquire data for “motion-from-smear”. Experimental results on images with both simulated smear and real smear, using the authors' “motion-from-smear” algorithm as well as a conventional motion estimation technique, are provided. The authors also show that temporal aliasing does not affect “motion-from-smear” to the same degree as it does algorithms that use displacement as a cue. “Motion-from-smear” provides an additional tool for motion estimation and effectively complements the existing techniques when apparent motion smear is present     

基于Contourlet旋转不变特征的遥感图像检索

除了具有纹理属性外,遥感图像中还包含大量的结构性边缘特征,如何有效捕捉这些特征中的信息进行检索,成为提高遥感图像检索效率的关键。文章依据Contourlet在离散域的多尺度几何分析的功能,提出一种利用Contourlet子带能量分布特性提取原始图像在多个尺度下的边缘方向信息进行检索的方法。针对Contourlet变换捕获不同特征方向能力的差别,文章采用正交补偿法加以改正,并通过傅里叶算子的处理,实现基于结构性边缘特征旋转不变的图像检索。实验结果表明,该检索算法对含有丰富规则边缘特征的遥感图像更为有效。     

Reduced cross‐talk in shutter‐glass‐based stereoscopic LCD

Abstract— It is expected that 3‐D will be the next step in the enhanced viewing experience. At present, there are two competing 3‐D technologies for glasses‐based consumer TVs: active shutter glasses and passive polarized glasses. With the ongoing reduction in response time of liquid‐crystal displays (LCDs), this article will focus on shutter‐glass‐based stereoscopic LCDs. In this paper, the properties of such a display system is described and it is demonstrated that by adding a line‐scanning backlight, the cross‐talk can be reduced to less than 1.4%, allowing for excellent 3‐D portrayal. For images of extreme contrast, this is perceivable, but not judged annoying by a panel of expert viewers. Which characteristics of the display and shutter glasses that should be optimized to create an inexpensive, cross‐talk‐free, 3‐D LCD are discussed.     

Oscillatory motion-based miniature magnetic walking robot actuated by a rotating magnetic field

Magnetic micro-robots have been proposed for use in biomedical applications. These studies focus on locomotion control using a gradient, alternating, and rotating magnetic fields at the sub-micro scale. However, this study focuses on a basic mechanism of active locomotion for diagnostic robots. Furthermore, the digestive intestine in the human body has a complex path in which locomotion methods can become either swimming or walking according to the inner condition. Therefore, we propose a new simple mechanism for amphibious locomotion within a rotating magnetic field using the three-axis Helmholtz coil system. The proposed magnetic robot consists of NdFeB permanent spherical magnets, flexible silicone tubes, and legs. Successive changes of actuation of yaw and roll motions cause alternating and walking motions. Direction of movement is decided by rotating the direction of the magnetic field (clockwise or counter-clockwise). In addition, turning directions are decided by the plane of the rotating magnetic field. A magnetic torque between the rotating magnetic field and the magnetic moments produce a constant walking pattern similar to a trotting gait. In addition, an oscillatory motion of the flexible robot body can generate a thrust force in the liquid. Finally, through the various experiments, we evaluate the capability of the locomotion.