中国科学院机构知识库网格系统: 检索

Comparison and simulation of subpixel imaging modes for linear CCD (EI CONFERENCE) 会议论文 OAI收割
2012 3rd International Conference on Information Technology for Manufacturing Systems, ITMS 2012, September 8, 2012 - September 9, 2012, Qingdao, China
作者: Li Y.; He B.; Li Y.; Li Y.; Li Y.

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Subpixel technique of linear CCD is effective to enhance the spatial resolution without increasing the focal length of optics and reducing the pixel size. To compare image quality of two main subpixel imaging modes quincunx sampling and four-point sampling a method to quantitatively evaluate image quality of subpixel based on MTF was proposed. The MTF of quincunx and four-point sampling modes were derived. Analytical results shows that theoretical limiting resolution of quincunx sampling and four-point sampling is improved to 1.4 and 1.86 times respectively and MTF values at Nyquist frequency of two modes are increased by 0.1106 and 0.1679 respectively. MTFA in (0 0.5) of two subpixel imaging modes were calculated and results illustrates that four-point sampling offers much more improvement with image quality than quincunx sampling at the cost of double amount of data. A model for simulating subpixel imaging using Matlab was established and simulation results of spoke target verify the theoretical analysis. (2012) Trans Tech Publications Switzerland.

Evaluation of the operating range for ground-based infrared imaging tracking system (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Zhang Z.-D.

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Ground-based infrared imaging tracking system (GIITS) is of great importance for aerial target warning and guard. The operating range is one of the key performance specifications on the other which should be calculated calculate the radiation power received on the detector in order to analysis whether the output signal meets the detection requirements or not analyzed and studied during the whole GIITS design process. The operating range is mostly influenced by a few factors without considering the effect of the background radiation. By improving of the traditional method including atmospheric attenuation a new operating range calculation model of the GIITS was established based on two requirements. One is that the image size of observed target should meet the requirement of the processor signal extraction. The number of the pixel occupied by target image should be more than 9. The other is that the signal noise ratio (SNR) of the GIITS should not be less than 5 to meet the requirements of the target detection probability and spatial frequency. The SNR calculation equation in form of energy is deduced and the radiation characteristic of the observed target and background are analyzed. When evaluate the operating range of the GIITS using the new method the performance of GIITS and feature of target and background. This paper firstly makes analysis and summarization on the definite localizations of the traditional operating range equation of the GIITS. The localizations are mainly in two aspects. On one hand we should successively calculate two operating range values according to two requirements mentioned above and choose the minimum value as the analytic result. In the end the dispersion of the image and the effect of image dispersion are not considered in the traditional method an evaluation of operating range for fighter aircraft is accomplished as an example. The influence factors in every aspect on operating range were explored by the calculated result. The new operating range calculation model provides the theoretical basis for the design and applications as well as the comprehensive evaluation of a GIITS. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Effect of gimbal point displacement on optical axis pointing precision in an image seeker (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011, April 15, 2011 - April 17, 2011, Wuhan, China
作者: Zhang X.; Zhang X.; Zhang X.

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A concentric glass spherical dome was usually chosen as the transparent window mounted in front of the optical lens in an image seeker. However optical ray had to change its direction when propagating through the dome due to refraction unless passing through the center of the dome which demanded gimbal point coincide with the center of the dome exactly. In fact gimbal point displacement could not be eliminating due to fabrication assembly and vibration therefore the optical axis pointing error generated. In this paper the effect of gimbal point displacement on optical axis pointing precision in an image seeker was analyzed and the theoretical expression of the optical axis pointing error was derived based on geometric optics and the error dynamics was explored by numerical. Take a visible light image seeker as a case the thickness of concentric glass spherical dome was 8mm and the inner radius was 72mm and the optical axis pointing errors varying dynamically with the look angle and the gimbal point displacement were shown in graph. When the gimbal displacement was 0.11mm the maximum optical axis pointing error was 0.054mrad that is equal to the instantaneous field of view (IFOV) corresponding to the camera system whose focal length was 120mm and pixel size was 6.5m. Furthermore with the gimbal displacement increasing the optical axis pointing error increased linearly. The analyzed results provided a theoretical basis for the displacement range which had to be limited strictly in the gimbal design process. 2011 IEEE.

Study on supper resolution reconstruction based on staggered arrays (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011, August 12, 2011 - August 14, 2011, Harbin, China
Yuan Z.; Xing Z.; Guang J.

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The image resolution can be improved without increasing the requirement to optical imaging systems' parameters and decreasing the size of CCD pixel by staggered arrays technology which arranges several CCDs in a specific mode. In this paper an image super resolution method of improving the image resolution for 1.5 times both in two directions by 4 linear arrays staggered based on this technology is presented which avoids the large computation in a single time by use of circulation method. This method is proved effective by the digital simulation and a simulated experiment platform is constructed to test its feasibility. The image resolution is improved for 1.42 times of the unreconstructed image according to the imaging experiment of resolution chart which is closed to 1.5 times in ideal case. And also the reconstructed and unreconstructed images are evaluated by the image information entropy which proves that the reconstructed image contains more information. 2011 IEEE.

Micro/Nano displacement measurement using sub-pixel DSCM 会议论文 OAI收割
international symposium on photoelectronic detection and imaging 2011: laser sensing and imaging; and biological and medical applications of photonics sensing and imaging, beijing, china, may 24, 2011 - may 26, 2011
LiXin-Zhong; TaiYu-Ping; NieZhao-Gang; ZhangLi-Ping; WangYa-Jun

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Micro/Nano displacement Digital speckle correlation method Sub-pixel Subset size

APPROACHES TO USING END-MEMBERS FOR SUB-PIXEL SNOW MAPPING WITH MODIS DATA IN QINGHAI-TIBET PLATEAU 会议论文 OAI收割
2010 Ieee International Geoscience and Remote Sensing Symposium, New York
Zhu Ji; Shi Jiancheng; Chu Hanfang; Du Jinyong; Wang Yaunhui

收藏 | 浏览/下载：27/0 | 提交时间：2014/12/07

typical end-member neighboring end-member unmixing of pixel AVIRIS DATA GRAIN-SIZE RESOLUTION COVER

Micro-motion exposure method based on PZT piezoelectric ceramics (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors, June 17, 2009 - June 19, 2009, Beijing, China
作者: Meng Z.; Meng Z.

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There mainly is laser digital photofinishing technique and digital photofinishing technique based on LCD consisting of TFT and LCOS in the digital photofinishing field at the present time. The former have a good many merit such as wide color gamut high processing rate large output size and high brightness but his cost is very high his maintain technique being comparatively complex that result in difficult use for people. The utilization ratio of the latter is low because of lower resolution and lower aperture ratio for LCD but the digital photofinishing based on LCD have lower cost and higher utilization ration being suitable for people's current standard of living. Considering above mentioned problem a micro-motion exposure method based on PZT piezoelectric ceramics used in digital image photofinishing is presented. The two-dimension micro-motion exposure system consisting of PZT piezoelectric ceramics LCD panel polarizing film and spring strip is designed. By means of PZT piezoelectric ceramics the LCD panel is removed about the one half of the pixel size of the LCD panel for four times from the original place at the same time imaging system is exposed four times at the printing paper. The software is used to control the time synchronization the exposure time and motion range of the LCD panel. The system has advantages such as shorter response time than 0.1seconds lesser motion error than 0.01 microns high stability and repeatability. Experimental results show that the proposed micro-motion exposure method improve the picture brightness and enlarge output size at the meantime reducing the cost of the system. 2009 SPIE.

An image matching algorithm based on sub-block coding (EI CONFERENCE) 会议论文 OAI收割
2nd International Workshop on Computer Science and Engineering, WCSE 2009, October 28, 2009 - October 30, 2009, Qingdao, China
作者: Li S.

收藏 | 浏览/下载：45/0 | 提交时间：2013/03/25

In order to improve the speed of matching algorithm and simplify the processing of existing sub-block coding matching a new template matching method combined local gray value encoding matching and phase correlation is proposed. Matching process is divided into rough matching and fine matching. Rough matching divides the image into certain size blocks called R-block sums the gray value of each R-block pixel encodes the R-block according to the gray value distribution of R-block with the adjacent R-block and matches by step between the template and each search sub-image. Then fine matching results are obtained using phase correlation according to initial match parameters. The time complexity of the proposed method is (M2) .The new algorithm is faster than traditional algorithm by two orders of magnitude and the speed has improved twice compared with existing sub-block coding method. Experiments demonstrate that the new algorithm is robust to the linear transformation of pixel grey value and image noise and it also has the stability of small-angle rotation. 2009 IEEE.

A MLP-PNN neural network for CCD image super-resolution in wavelet packet domain (EI CONFERENCE) 会议论文 OAI收割
2008 International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2008, October 12, 2008 - October 14, 2008, Dalian, China
Zhao X.; Fu D.; Zhai L.

收藏 | 浏览/下载：72/0 | 提交时间：2013/03/25

Image super-resolution methods process an input image sequence of a scene to obtain a still image with increased resolution. Classical approaches to this problem involve complex iterative minimization procedures typically with high computational costs. In this paper is proposed a novel algorithm for super-resolution that enables a substantial decrease in computer load. First decompose and reconstruct the image by wavelet packet. Before constructing the image use neural network in place of other rebuilding method to reconstruct the coefficients in the wavelet packet domain. Second probabilistic neural network architecture is used to perform a scattered-point interpolation of the image sequence data in the wavelet packet domain. The network kernel function is optimally determined for this problem by a MLP-PNN (Multi Layer Perceptron - Probabilistic Neural Network) trained on synthetic data. Network parameters dependent on the sequence noise level. This super-sampled image is spatially Altered to correct finite pixel size effects to yield the final high-resolution estimate. This method can decrease the calculation cost and get perfect PSNR. Results are presented showing the quality of the proposed method. 2008 IEEE.

Design of dual-FOV refractive/diffractive LWIR optical system (EI CONFERENCE) 会议论文 OAI收割
3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies, AOMATT 2007: Advanced Optical Manufacturing Technologies, July 8, 2007 - July 12, 2007, Chengdu, China
作者: Wang L.-J.; Zhang J.-P.; Wang L.-J.; Zhang X.; Zhang X.

收藏 | 浏览/下载：44/0 | 提交时间：2013/03/25

An infrared-optical zoom system using binary element is proposed in this paper. The two main advantages of the zoom system introducing here are: bigger F-number and lower cost. The primary optical properties are: F/#=1 Second Others zoom ratio =1:4 binary element is used to correct the chromatical aberration by taking the advantage of negative dispersion characteristics and the cost of the system is lower than that of conventional ones with Zinc Selenide (Znse) material at the same level. In the binary element is rotational symmetric with one step which is easy to fabricate in order to balance 5th spherical aberration and dual field are 26.6 and 5.6respectively. Wider field of view is used for search and the smaller one is used for imaging details. This system uses un-cooled infrared detector with 320240 pixels and 45m pixel size. The F-number matches the sensitivity range of the detector array. Three aspects are considered during design process to make the system more satisfactory and more achievable. First 5th coma aberration and 5th astigmatic aberration the manner of zoom is accomplished by exchanging tow lenses into the smaller field of view system layout. The lens exchange manner faces the requirement of simple system structure and good image quality in both focal points. It can also make the system more feasible in the alignment process than mechanical-zooming manner and optical-zooming manner high-order asphere surfaces with 2th order to 10 th order are also hired in the system. Asphere surface is useful in compressing the system and improving optical system transmittance. This kind asphere surface is on industrial level featuring low cost and easy to fabricate. It is shown that good image quality can achieved by implementing five Germanium lenses and the transmittance of system is 72%. All aberrations are diffraction-limited both spherical aberration and astigmatic aberration are corrected. When the field of view(FOV) is 26.6 and the focal length is 152mm MTF at Nyquist frequency(11lp/mm) is great than 0.7. The spherical aberration is -0.0073. The coma aberration is 0.0978 and the astigmatic aberration is -0.013. When the field of view(FOV) is 5.6 and the focal length is 38mm MTF at Nyquist frequency is great than 0.8 with spherical aberration -0.0046 the coma aberration 0.055 and astigmatic aberration 0.034.