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Liu F.,Yantai Naval Aeronautical and Astronautical University | Guo S.,Yantai Naval Aeronautical and Astronautical University | Shen T.,National Defense Science and Technology Information Center | Ma X.,Yantai Naval Aeronautical and Astronautical University
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2015

Celestial navigation technology has entered a new stage of development with the development of electronic technology and computer technology. Otherwise it has been widely used in satellite, space shuttle, long-range missiles and other spacecraft. Star centroid location for celestial navigation is the key technologies. Due to the strong sky background, near-infrared stellar images which are taken during the day have the low signal noise ratio. First, this paper adopts the method of information entropy to make analysis the stellar images energy distribution. And then we proposed a method for star target centroid located based on multi-step minimum energy difference. This method uses the linear superposition to narrow the centroid area, using the symmetry of the stellar energy distribution to obtain the centroid when the minimum difference appears. We test the modal on natural pictures to verify the accuracy. Experiments show that it has good effect to calculate the centroid with low SNR conditions. © 2015, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved. Source


Li Z.,Yantai University | Shen T.,National Defense Science and Technology Information Center | Lou S.,Yantai University
Infrared Physics and Technology | Year: 2016

In order to correct the nonuniformity noise of the IR imaging system, a nonuniformity correction deghosting algorithm based on high-brightness region detection was proposed. Firstly, the bilateral filter was used to filter the image. The high-brightness regions in the result image were detected, and the correction factors corresponding to the regions were reduced. And then, the positions were detected which are high-brightness pixels in former frame but are not in current frame, and the correction factors corresponding to the regions were enlarged. Thus, the wrong update of the correction factor caused by high-brightness region of both the current frame and the previous frame was reduced. The correction method was validated using a real image sequence. The experimental results showed that the suppression effect of the proposed algorithm on the 'ghost' effect caused by the high-brightness region is better than the other two algorithms named SLTH-NUC and BFTH-NUC, respectively. Moreover, the proposed algorithm can also suppress the 'ghost' effect caused by the sharp edge of the scene. © 2016 Elsevier B.V. All rights reserved. Source


Shi H.,Yantai Naval Aeronautical and Astronautical University | Li Z.,Yantai Naval Aeronautical and Astronautical University | Shen T.,National Defense Science and Technology Information Center | Lou S.,Yantai Naval Aeronautical and Astronautical University
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2016

Under sampling leads to aliasing effect which have seriously effect on the image quality for infrared focal plane arrays. According to the imaging processing of staring system, sampling process of detector was analyzed in the time domain to study aliasing effect on image quality using a quantitative method in the frequency domain. Simulation experiment on aliasing phenomenon of periodic and aperiodic objects based on the reason of aliasing effect was completed. Simulation experiment show that aliasing distortion phenomenon will be exist in periodic objects, but there will be zigzag stripe in aperiodic objects. It can be concluded that aliasing distortion is small in low frequency and noise tends to mask the target pattern, but aliasing distortion is serious in high frequency where aliasing is dominant, this has a certain reference value for eliminating the influence of aliasing confusion and system parameter design. © 2016, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved. Source


Li Z.,Yantai Naval Aeronautical and Astronautical University | Shen T.,National Defense Science and Technology Information Center | Lou S.,Yantai Naval Aeronautical and Astronautical University
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2016

Vignetting effect during infrared imaging is the phenomenon that image plane center region is bright but edge is dark. The vignetting effect is very serious, so it is necessary to correct the vignetting effect when the system is used. First, the cause of the vignetting effect was analyzed. Then, a fast correction method was proposed. The background information was extracted, and the background gray distribution was obtained by polynomial approximation. To evaluate the correction effect, the concept of variance between rows which has statistical significance was put forward. To verify the correction method, two kinds of scenes were used. Variance between rows was reduced to 13.6% and 3.8% compared with uncorrected images. The effect of the correction method is ideal. © 2016, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved. Source


Shen T.,National Defense Science and Technology Information Center | Shi H.,Yantai Naval Aeronautical and Astronautical University | Lou S.,Yantai Naval Aeronautical and Astronautical University | Li Z.,Yantai Naval Aeronautical and Astronautical University
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2015

Fill factor is an important parameter for the design of detector arrays, and it's necessary to research fill factor influence on image quality of micro-scanning system. One model of micro-scanning (2×2) as an example, on the basis of the detailed analysis of micro -scanning can reduce aliasing which is created by detector due to under sampling, output images were simulated with the case of different fill factors. Quantitative analysis on the simulation images from the perspective of image quality assessment was based on structure similarity. The simulation results show that the increase of fill factor can reduce aliasing effect and improve the quality of imaging. Pointed out that fill factor of detector can improve the quality of the image, but the influence on image quality is limited and degree on the improvement of the image was not large, which provide the theoretical and applied research for the design of micro-scanning imaging system. ©, 2015, Chinese Society of Astronautics. All right reserved. Source

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