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Record 85 of
Title:Image degradation of large-aperture R-C optical system induced by micro-vibration
Author(s):Wang, Hongjuan(1,2); Wang, Wei(1); Liu, Qimin(1,2); Li, Gang(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8759 Issue: DOI: 10.1117/12.2014808 Published: 2013
Abstract:As part of the spacecraft optical loads, space camera will be subject to all working components in aircraft and space environment disturbance on-orbit, which have great influence on image resolution and image contrast, especially for large-aperture Ritchey-Chretien (R-C) optical system. This article puts forward a new method about estimating image quality degradation induced by micro-vibration. With the space coordinate transformation, the amount of optical elements jitter expressed by six variables are acquired, then the data can be imported to optical design software Code V, image motion and the root mean square(RMS) diameter will be quickly attained, then the image quality could be judged. The simulation and analysis are of significance for studying the influence of satellite micro-vibration on imaging system. For high resolution large-aperture R-C imaging system, this study provides important reference for system control and isolation. ? 2013 SPIE.
Accession Number: 20131516204324
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Record 86 of
Title:Research on detection and correction of defective pixels of LASIS
Author(s):Jing, Juanjuan(1); Lv, Qunbo(1); Shi, Dalian(2)
Source: IST 2013 - 2013 IEEE International Conference on Imaging Systems and Techniques, Proceedings Volume: Issue: DOI: 10.1109/IST.2013.6729652 Published: 2013
Abstract:Due to the imperfections in producing, a finite number of pixels in an array will be defective. Regarding a Fourier transform Imaging spectrometer, the existence of defective pixels will not only affect the quality of the image, but also cause interferogram extraction error, and then result in a distortion of the reconstructed spectrum. So the defective pixels must be accurately distinguished and eliminated by data processing. In this paper, according to the characteristic of the Fourier transform Imaging spectrometer, a distinguishing and eliminating method is carried out. The Fourier transform Imaging spectrometer is illuminated by a uniform light. The data is fitted in the spatial dimension; the error between the actual data and the fitted data is computed and divided by the standard deviation. By choosing a proper threshold value, the cold, hot and non-saturated pixels can be effectively distinguished. Single defective pixels can be effectively corrected by spatial dimension interpolating; for clustered defective pixels, spatial dimension interpolating and interference dimension fitting are taken and the result is averaged. The experimental result proves that this method is effective and also efficient both for uniform light illuminated data and push broom data. ? 2013 IEEE.
Accession Number: 20140917407639
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Record 87 of
Title:Optical current sensor technology in power system
Author(s):Wang, Lihui(1,2); Sun, Jian(3); Ji, Jianfei(3)
Source: Key Engineering Materials Volume: 562-565 Issue: DOI: 10.4028/www.scientific.net/KEM.562-565.242 Published: 2013
Abstract:With power voltage and capacity improved greatly, power transmission system put a higher demand on reliability and safe operation of electrical equipments. Electromagnetic sensors and other conventional detection equipment can no longer meet the needs of the power system, and new sensing measurement techniques led to optical current and voltage sensing technology. As their unique advantages, optical current sensing technology is get in-depth study and attention, and gradually used in power system engineering applications. Combined with domestic and foreign research progress of optical current sensor, we analyzed the basic principles of the photoelectric sensing technology and problems faced in power system applications and key technologies. Focused on sensing characteristic differences of photoelectric sensors and electromagnetic sensor, we analyzed the effects of photoelectric sensor on protection, monitoring and control, measurement systems in data processing and data transmission, and study the corresponding key technology. Combined with the development of modern power system, we prospect optical current sensor sensing technology opportunities and challenges in smart grid. ? 2013 Trans Tech Publications Ltd, Switzerland.
Accession Number: 20133816744625
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Record 88 of
Title:Visual-textual joint relevance learning for tag-based social image search
Author(s):Gao, Yue(1); Wang, Meng(2); Zha, Zheng-Jun(3); Shen, Jialie(4); Li, Xuelong(5); Wu, Xindong(6,7)
Source: IEEE Transactions on Image Processing Volume: 22 Issue: 1 DOI: 10.1109/TIP.2012.2202676 Published: 2013
Abstract:Due to the popularity of social media websites, extensive research efforts have been dedicated to tag-based social image search. Both visual information and tags have been investigated in the research field. However, most existing methods use tags and visual characteristics either separately or sequentially in order to estimate the relevance of images. In this paper, we propose an approach that simultaneously utilizes both visual and textual information to estimate the relevance of user tagged images. The relevance estimation is determined with a hypergraph learning approach. In this method, a social image hypergraph is constructed, where vertices represent images and hyperedges represent visual or textual terms. Learning is achieved with use of a set of pseudo-positive images, where the weights of hyperedges are updated throughout the learning process. In this way, the impact of different tags and visual words can be automatically modulated. Comparative results of the experiments conducted on a dataset including 370+images are presented, which demonstrate the effectiveness of the proposed approach. ? 1992-2012 IEEE.
Accession Number: 20130115862016
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Record 89 of
Title:Improved Bayer-pattern demosaicking and its hardware design
Author(s):Zhu, Bo(1,2); Wen, De-Sheng(1); Wang, Fei(3)
Source: Guangdianzi Jiguang/Journal of Optoelectronics Laser Volume: 24 Issue: 6 DOI: Published: June 2013
Abstract:In order to improve the quality of demosaicked images and reduce the complexity of its hardware design, an improved Bayer-pattern demosaicking method is presented. Firstly, the second-order Laplacian interpolation filter is adopted to interpolate the missing green samples G?H and G?V at red and blue pixels. And then, in every red or blue location, we calculate the horizontal chrominance values R-G?H, B-G?H and vertical ones R-G?V, B-G?V. Next, we calculate and compare the horizontal chrominance gradient and the vertical one for choosing the missing G?. After the green channel has been reconstructed, we interpolate R? and B? as the average of the four nearest neighbors. By now, the full color image is reconstructed. Experimental results prove that on average the improvement is 15 dB over the bilinear algorithm (BI) in peak signal-to-noise ratio (PSNR) and it appears to produce visually more pleasant color image details with color artifacts greatly suppressed. Furthermore, the computational cost of the proposed algorithm is as simple as the linear algorithm, so the interpolation can be hardware processed in real time. Now, the proposed algorithm is implemented with Xilinx FPGA and used in our camera system, and the perfect restoration quality and effectiveness can meet the requirement of system design.
Accession Number: 20132916509277
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Record 90 of
Title:Focused plenoptic camera and spatial resolution improving technology
Author(s):Zhao, Juan Ning(1,2); Dong, Xiao Na(2); Yuan, Suo Chao(1,2)
Source: Advanced Materials Research Volume: 710 Issue: DOI: 10.4028/www.scientific.net/AMR.710.419 Published: 2013
Abstract:The focused plenoptic cameras based on the rays resampling of microlens array on the image formed by main lens, captures radiation on sensor includes the 4D radiance information. Because of both spatial and angular information are recorded on the sensor of fixed pixels number, when rendering image with fixed view there are limited pixels from sub_image are adopted, this results in disappointingly low resolution of the result image. Our approach presents a new approach to rendering an image with higher spatial resolution than the traditional approach, allowing us to render high resolution images that meet the high requirements. ? (2013) Trans Tech Publications, Switzerland.
Accession Number: 20133016530638
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Record 91 of
Title:Development of the electronics system prototype of the panoramic camera for space applications
Author(s):Duan, Yong-Qiang(1,2); Gao, Wei(1); Qiao, Wei-Dong(1); Yang, Jian-Feng(1); Wen, De-Sheng(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8907 Issue: DOI: 10.1117/12.2034858 Published: 2013
Abstract:The stereoscopic panoramic camera is a kind of important optical payload for space applications. It can image the full 360° in azimuth to the goal scene and obtain high resolution three-dimensional images. Many science investigations can be conducted by scientists with these images, such as the analysis for the planet terrain and the geology. This kind of payload has common features such as light-weight, miniaturization, and lower power consumption. This paper presents the development of a stereoscopic, panoramic imaging system for space applications, which is a typical staring binocular stereo imaging system and consists of two identical digital cameras. Each camera was build based upon a CMOS APS (Complementary Metal Oxide Semiconductor Active Pixel Sensors) and a high density FPGA (Field Programmable Gate Array). The camera has the features with the weight of about 210g and the power consumption of about 660mW. In this paper, the design details of the electronics for the specifications above are emphasized, and the designs and implements of the FPGA are particularly discussed. Finally, the verification and experiment results for the stereoscopic panoramic camera show that the design methodology is feasible. ? 2013 Copyright SPIE.
Accession Number: 20141317510222
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Record 92 of
Title:The research of relay lens coupling in image intensified camera
Author(s):Sun, Xin(1); Hu, Bing-Liang(1); Zou, Chun-Bo(1); Bai, Qing-Lan(1); Wang, Le(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8912 Issue: DOI: 10.1117/12.2034709 Published: 2013
Abstract:Image Intensified CCD (ICCD) camera is widely used in the field of low-light-level image detection. The crucial part of ICCD, coupling component, which realizes the image transmitting between the image intensifier and detector, affects the final performance of the ICCD camera significantly. There are two means of coupling: relay lens and optical fiber taper (OFT). OFT has the merits of small volume and relatively high coupling efficiency, therefore it is commonly used in the portable devices or applications with less precision demands. However, relay lens turns out to be a better solution other than OFT for the applications with no volume and weight restrictions, since it provides higher resolution, perfect image plane uniformity and manufacture flexibility. In this paper, we discuss a methodology of high performance relay lens design and based on the method a solid design is proposed. There are three major merits of the lens design. Firstly, the lens has large object space numerical aperture and thus the coupling efficiency reaches 5% at the magnification of 0.25. Secondly, the lens is telecentric in both sides of object space and image space, this feature guarantees uniform light collection over the field of view and uniform light receiving on the detector plane. Finally, the design can be conveniently optimized to meet the needs of different type of image intensifier. Moreover, the paper presents a prototype ICCD camera and a series of imaging experiment as well. The experiment results prove the validity of the foregoing analysis and optical design. ? 2013 SPIE.
Accession Number: 20141317521645
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Record 93 of
Title:Proposal on a single-shot correlator for measuring contrast ratio based on optical replication
Author(s):Yuan, Suochao(1,2); Gao, Limin(1); Zhao, Juanning(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8796 Issue: DOI: 10.1117/12.2006555 Published: 2013
Abstract:We propose a new idea to measure the temporal contrast of laser pulses in this paper. Unlike the traditional time-to-space transformation method, the design in this paper can be called a somewhat time-to-time transformation. A single-shot pulse beam is simultaneously divided into two separate beams by a beam splitter. The two beams then enter a pair of optical replicators respectively to generate two pulse sequences that have equal time intervals respectively. The time interval of the two sequences alters by about 100fs that we can use one sequence to scan the other at a time resolution of 100fs through a nonlinear crystal. The time resolution depends on the altering of time interval and the time window depends on the pulse number of the sequence. This method can avoid the spatial modulation of the laser pulse. On the other side, the time resolution and time window are adjustable. It is also possible to measure the high contrast with a low-dynamic- range detector by attenuating the power of each pulse in the sequence respectively. ? 2013 SPIE.
Accession Number: 20133216576219
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Record 94 of
Title:A multi-focus image fusion method based on image blocks
Author(s):Wang, Qi(1,2); Song, Zongxi(1); Gao, Wei(1); Zhao, Bingjie(1,2)
Source: Journal of Information and Computational Science Volume: 10 Issue: 16 DOI: 10.12733/jics20102360 Published: November 1, 2013
Abstract:This paper presents a method for fusing multi-focus images directly based on analyzing image blocks. Firstly, we separate the clear domains and fuzzy domains by setting a threshold value for the average gradients difference of image blocks corresponding. In clear domains, all the pixels are selected directly as the corresponding pixels in the fused image instead of any kind of transform. However, in processing fuzzy domains, we use a fusion method based on the mean gradients of image blocks. The experimental results show that our method is effective and obviously superior to the multi-scale decomposition-based methods such as wavelet transform and wavelet packet transform. ? 2013 Binary Information Press.
Accession Number: 20134917048378
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Record 95 of
Title:Fusion of infrared and visible image based on target extraction and contourlet transform
Author(s):Zhao, Bingjie(1,2); Gao, Wei(1); Song, Zongxi(1); Wang, Qi(1,2)
Source: Journal of Information and Computational Science Volume: 10 Issue: 15 DOI: 10.12733/jics20102267 Published: October 10, 2013
Abstract:The fusion of the infrared and visible images has been widely used in object recognition, night vision and military affairs, which is a popular research field. A new image fusion method based on target extraction and contourlet transform is proposed in this paper. Commonly, the traditional image fusion method neglect differences between the targets and background of the infrared and visible images, resulting in the poor distinct or weak identification of the fused image. In order to take full advantage of the differences, we extract firstly the interested targets of infrared image, which are fused with the visible image by the method of regional similarity. Therefore we obtain a new visible image with more target information, while reserve the visible background information. Secondly, to obtain more complementary information, contourlet transform is utilized to fuse the new visible image and the source infrared image. In addition, based on the different characters of low frequency and high frequency coefficients, we choose different rules to fuse the contourlet coefficients. In low frequency processing, the method based on the fuzzy theory is used, while we ascertain the high fusion coefficients by the Tenenbaum's algorithm. Experiments are carried out and the results show that our method is effective and the fused images are better than those resulting from wavelet transform and contourlet transform both in visual quality and in quantitative evaluations. ? 2013 Binary Information Press.
Accession Number: 20134516948949
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Record 96 of
Title:Detecting method of right-angled prism tilting
Author(s):Zhao, Junli(1,2); Wu, Yiming(1); Gao, Limin(1)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 42 Issue: 1 DOI: Published: January 2013
Abstract:In the azimuth aiming system, the sensitive-axis direction of inertial unit is monitored usually with the help of right-angled prism. The azimuth aiming error was produced by the right-angled prism tilting, through building the mathematical model of the influence of prism tilting on the aiming accuracy, the accurate vector expression was founded, in addition, the conventional measuring way and technique were introduced, furthermore, a new detecting and calibrating method of prism tilting based on the rhombic prism was studied, and some leading causes that affecting the measuring accuracy of the system were discussed. Then, experiment platform was built based on our own rhombic-equipment. The acquired data proves that the measurement results are greatly influenced by the device level state along the direction of prism titling, the calibrated system has achieved high measuring accuracy less than 10″. At the same time, this new system has obvious advantages on high measuring efficiency, and can be operated very simply and conveniently, it has a very important practical significance to improve the azimuth aiming precision.
Accession Number: 20131316153590
