中国科学院机构知识库网格系统: 检索

Local difference-based active contour model for medical image segmentation and bias correction 期刊论文 OAI收割
IET Image Processing, 2019, 卷号: 13, 期号: 10, 页码: 1755-1762
作者: Niu, Yuefeng; Cao, Jianzhong

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收藏 | 浏览/下载：80/0 | 提交时间：2019/09/25

image segmentation medical image processing two-phase model medical images LBDE model precise segmentation results comparative models local difference-based active contour model medical image segmentation bias correction local bias field difference estimation model smooth orthogonal basis functions clustering criterion function measured image local region accurate segmentation results level set evolution process

Local difference-based active contour model for medical image segmentation and bias correction 期刊论文 OAI收割
IET IMAGE PROCESSING, 2019, 卷号: 13, 期号: 10, 页码: 1755-1762
作者: Niu, Yuefeng; Cao, Jianzhong

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收藏 | 浏览/下载：33/0 | 提交时间：2020/06/05

image segmentation medical image processing two-phase model medical images LBDE model precise segmentation results comparative models local difference-based active contour model medical image segmentation bias correction local bias field difference estimation model smooth orthogonal basis functions clustering criterion function measured image local region accurate segmentation results level set evolution process

Centroid localization algorithm based on bicubic interpolation gray square weighted (EI CONFERENCE) 会议论文 OAI收割
2012 3rd International Conference on Advances in Materials and Manufacturing Processes, ICAMMP 2012, December 22, 2012 - December 23, 2012, Beihai, China
作者: Zhou J.

收藏 | 浏览/下载：161/0 | 提交时间：2013/03/25

The 3D coordinates of measured point is embodied in 2D image coordinate of the optical characteristic point via the visual measurement system. Based on the gray square weighted centroid localization algorithm the paper presents bicubic interpolation gray square weighted centroid localization algorithm increases the number of effective pixels around the optical characteristic point imaging center and reduces noise error via the gray square weighted improves the imaging center location accuracy of optical characteristic point realizes the accurate location of the optical characteristic points. Results indicate application of the proposed algorithm to location the standard tolerance along the direction of x is 0.0022 Pixel the standard tolerance along the direction of y is 0.0023 Pixel compared with the others the standard tolerance is minimum and discrete to a lesser degree distancing ideal image point that is the proposed algorithm has higher location accuracy. The maximum tolerance along the direction of x is 0.008 Pixel the one along the direction of y is 0.007 Pixel compared with the other two algorithms the maximum tolerance is minimum.Results indicate that the stability of the proposed algorithm is better. (2013) Trans Tech Publications Switzerland.

Design of motion compensation mechanism of satellite remote sensing camera (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Gu S.; Yan Y.; Xu K.; Jin G.

收藏 | 浏览/下载：58/0 | 提交时间：2013/03/25

The research of the accurate measure of static transfer function for the TDI CCD camera (EI CONFERENCE) 会议论文 OAI收割
3rd International Photonics and OptoElectronics Meetings, POEM 2010, November 2, 2010 - November 5, 2010, Wuhan, China
Guo-Ning L.; Long-Xu J.; Jian-Yue R.; Wen-Hua W.; Shuang-Li H.

收藏 | 浏览/下载：32/0 | 提交时间：2013/03/25

In the test course of static transfer function of TDI CCD camera because of the influence that gets environmental and artificial etc. factor the value of static transfer function measured at any time is between unceasing fluctuation so make accuracy reduce. To solve this problem a kind of accurate measurement technique of static transfer function is put forward. First before carrying out the measure of static quiet of transfer function the best test point of transfer function of the TDI CCD camera must be determined it is parallel to guarantee the rectangle target surface of parallel optical pipe and camera focal plane maintenance parallel and again guarantee target strip in rectangle target and TDI CCD in camera focal plane maintenance vertical. TDI CCD catches rectangle target image per 1000 lines of target mark image as a measures sample of static transfer function exclude because of atmosphere tremble twisted vague rectangle target mark image retain 500 distinct and steady target mark image as measure sample set. Then calculate the static transfer function of each measure sample respectively take the average of all static quiet transfer function in measure sample set as the static transfer function of camera. Finally the measure of the static transfer function for TDI CCD camera makes error analysis. Experimental results indicate that the value of the static transfer function of TDI CCD camera measured with this kind of method is 0.2923 with before measurement technique comparison the value of static transfer function has raised 0.02 makes the accuracy of the measure of static transfer function have gotten raising.

Electro-optical imaging system identification using pseudo-random binary pattern (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China
Le Y.; Jian W.; Jianzhong Z.; Qiang S.; Jianzhuo L.

收藏 | 浏览/下载：39/0 | 提交时间：2013/03/25

A method using pseudo-random binary pattern is developed for electro-optical imaging system identification. The imaging system is taken as a stable linear time-invariant and causal filter and its transfer function is measured through the pseudo-random binary sequence impulse responses identification. A digital mirror device (DMD) light projector is developed as the target generator and wavelet thresholding is used to denoise the captured image. Pre-filtering spectral estimation algorithm with adaptive parameter selection is also proposed for the identification process overcoming the challenge brought by the size limit derived from the optical isoplantic region. Simulations and experiments are presented to show the effectiveness of the proposed method.0-64. 2010 IEEE.

Far-field focusing of laser beam based on digital image processing techniques (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Imaging and Multimedia Technology, October 18, 2010 - October 20, 2010, Beijing, China
作者: Zhao S.; Tian Y.-Z.; Liu L.-S.; Guo J.; Zhang H.-Y.

收藏 | 浏览/下载：40/0 | 提交时间：2013/03/25

In order to lead the laser beam transmit in the atmosphere convergently an experiment of laser focus at the distance of 450m and 300m has been operated in the outdoor place. The actual manipulations are as follows: Firstly the laser was collimated by a beam expander then the near-parallel laser beam was transmitted with a Galileo telescope system and the distance between the concave lens and the convex lens can be tuned through a precise displacement platform so the focus of the system changed due to the tiny displacement of the concave lens. Secondly the average power of the laser spot can be measured using power meter the power is 47.67mW and the standard deviation is 0.67mW while the focal length is 450m. Thirdly the energy distribution was found through the laser beam analyzer. The spot images were saved using the beam analyzer then the saved image can be processed with Matlab software afterwards. The function named EDGE and Sobel operator was used in the pre-processing of the saved image then method of median filter was used in the course of image de-noising and 53H filter was adopted in the signal analysis. The diameter of laser spot was obtained by the method above the diameter is 5.56mm and the standard deviation is 0.24mm. The spot center excursion is 0.56mm it is 10.43% of the total diameter of the laser spot. At last the key factors of the energy dissipation in the focusing system can be summarized as follows: restriction of the diffraction limit attenuation in the atmosphere geometrical aberration of optical system and the diffraction limit and the geometrical aberration are significant in the three factors above so we can reduce the impact of the both factors during the design of optical system. The reliable referenced data of the system design can be acquired through the primary experiment research. 2010 SPIE.

Research on automatic Hartmann test of membrane mirror (EI CONFERENCE) 会议论文 OAI收割
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, April 26, 2010 - April 29, 2010, Dalian, China
作者: Zhang P.

收藏 | 浏览/下载：46/0 | 提交时间：2013/03/25

Electrostatic membrane mirror is ultra-lightweight and easy to acquire a large diameter comparing with traditional optical elements so its development and usage is the trend of future large mirrors. In order to research the control method of the static stretching membrane mirror the surface configuration must be tested. However membrane mirror's shape is always changed by variable voltages on the electrodes and the optical properties of membrane materials using in our experiment are poor so it is difficult to test membrane mirror by interferometer and null compensator method. To solve this problem an automatic optical test procedure for membrane mirror is designed based on Hartmann screen method. The optical path includes point light source CCD camera splitter and diffuse transmittance screen. The spots' positions on the diffuse transmittance screen are pictured by CCD camera connected with computer and image segmentation and centroid solving is auto processed. The CCD camera's lens distortion is measured and fixing coefficients are given to eliminate the spots' positions recording error caused by lens distortion. To process the low sampling Hartmann test results Zernike polynomial fitting method is applied to smooth the wave front. So low frequency error of the membrane mirror can be measured then. Errors affecting the test accuracy are also analyzed in this paper. The method proposed in this paper provides a reference for surface shape detection in membrane mirror research. 2010 Copyright SPIE - The International Society for Optical Engineering.

The method on the measurement of the aircraft attitude by the spatial cosines relationship of the single station and planes to the intersection the multi-station of electro-optical theodolite (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China
Zhao L.-R.; Cao Y.-G.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

In order to realize the aircraft attitude measurement The paper advances electro-optical theodolite methods of measuring the aircraft attitude by using the spatial cosines relationship the single station theodolite and how to use intersection of the multi-station theodolite. The single station theodolite was introduced in a measured distance from the aircraft posture information. An exhaustive approach was used to access to the aircraft axis of the feature points and the location in the space was used to obtain space posture parameters. The multi-station theodolite was introduced to get the information of the aircraft flight attitude by method of using planes to the intersection. Two-dimensional image to obtain objective axis by fitting algorithm using Hough transform. And then Calculate the vertical distance of the origin to the target of the central axis and the origin to the target of the central axis of the angle between the normal and the X-axis obtaining the linear equation in the two-dimensional plane. Two-dimensional axis of the target image and the camera system's optical center only identified a space plane. The aircraft yaw axis angle and pitch angle can be obtained by getting the space axis using plains to the intersection method. Experimental results show that attitude angle error of the single station theodolite is less than 1 when its distance is less than 6000m and attitude angle error of the multi-station theodolite is less than 0.6 when its intersection angle is between 30 and 150. In this paper according to test result of precision comparing the mathematical model is correct and the algorithm is reasonable in extracting effective parameters of the aircraft's attitude. 2010 IEEE.

Attitude determination of small, dim and high-speed targets based on multi-CMOS intersecting system (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Information Science and Engineering, ICISE2010, December 4, 2010 - December 6, 2010, Hangzhou, China
作者: Li M.; Zhao L.; Wang J.

收藏 | 浏览/下载：39/0 | 提交时间：2013/03/25

In order to measure attitude of small dim and high-speed targets in shooting range intersecting system based on multiple high-speed CMOS cameras was introduced in this paper. CMOS cameras were laid near from objects for small size using multiple CMOS cameras to compose intersecting system for big number of targets tested and selecting CMOS camera between CMOS and CCD for low cost and considering damage to measurement equipment of objects tested. Pitch angle and yaw angle were measured by extracting axle wire through image processing image sequences were obtained from cameras laying on two sides. Velocity of objects was calculated by least square curve-fitting acquiring coordinate of centroid on image received by CMOS camera laying below effective viewing field. One CMOS camera was laid on right ahead for measuring roll angle. Station mode introduced in this paper has virtue of low cost and free extending. 2010 IEEE.