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To accurately discern the parameters of high frequency vibration blur model on a single TDI image, the research analyzes the imaging function when high frequency vibration occurs in TDI mode. The method of simplifying the vibration model is offered and verified, which promises the MTF will be only related with motion angle and vibration amplitude. Three algorithms for motion direction discerning are compared with one another, which are Radon transform, autocorrelation analysis and cepstral method. The conclusion reveals that cepstral method can measure the most accurate motion angle. Four algorithms for vibration amplitude discerning are compared, which are the quadratic Radon transform, cepstral analysis, autocorrelation analysis and direct analysis on frequency spectrum. It reveals that direct analysis on Log frequency spectrum is the most accurate for vibration amplitude. The research suggests that composition of cesptral method and direct analysis on log frequency spectrum could obtain the highly accurate parameters in high frequency vibration model.

Aerial images captured using time delay and integration (TDI) charge-coupled devices (CCDs) could be blurred by three types of motion: forward image motion, turbulence disturbance and high frequency vibration. This work proposes a method to separately construct the three deterministic models by discerning or calculating the parameters from a single image blurred by all the three ones. Based on these models, we catch and separate the features existing in the power spectrum diagram, and select the methods with the best identification accuracy to the parameters. The results show the approach we mention can promise the accuracy of the determined parameters, which is helpful to improve the result of blind restoration algorithm.

In the spectral imaging process of interference imaging spectrometer, the impact caused by motion errors of satellite platform is not only the degradation of spatial resolution but also the aliasing and distortion of spectral information. The degradation function is modeled though analyzing the degradation mechanism of spectral imaging. And a correction algorithm based on interference sequences is proposed to solve this problem. In this algorithm, the interference sequences is regarded as an integer and the degradation model is thought to be three-dimensional, including two spatial dimensions and one spectral dimension. And the degraded interference sequences are the convolution of the original sequences and the degradation function. According to the vibration data measured by POS on the satellite, the degradation function can be obtained. Then the corrected interference sequences can be got by de-convolution of the degraded sequences and the degradation function though Hopfield neural network based on continuous variation of states. And by reconstructing of the corrected sequences, the corrected images and spectrums can be got finally. The simulated results show that this algorithm can correct the degradation of images and the distortion of spectrums caused by motion errors of satellite's attitudes effectively.

In this paper, we introduce a new edge-preserving nonlinear filter for removing the mix of Gaussian and impulse noise. Built from Prasun Choudhury and Jack Tumblin’s trilateral filter, the new algorithm incorporate a local gradient statistic for detecting corrupted pixels in images with impulse noise and a switching mechanism for smoothing the gradients of impulse noise samples and the gradients of impulse noise-free samples with different parameters. If the central pixel is impulse-like and has a high statistical value in gradient domain, the impulsive component of the weight in gradient bilateral filter is more heavily to suppress large impulses. It smoothes image toward a sharply-bounded, gradient piecewise-linear approximation which provides stronger noise reduction and better edge-limited smoothing behavior. Compared to most other spatial domain nonlinear filters, the proposed algorithm consistently yields good results in removing the mix of Gaussian and impulse noise and more notable edge-limited smoothing behavior. Like the trilateral filter, the proposed algorithm easily ex tends to N-dimensional signals. Keywords: Trilateral filter, Gaussian noise, Impulse noise, mixed noise, De-noising, Nonlinear filter

In this paper, the theoretical analysis and numerical simulation with regard to the temperature characteristics of LiNbO 3 crystal electro-optic modulator are putted in practice by applying linear electro-optic effect coupling wave theory. The temperature stable conditions of LiNbO 3 crystal electro-optic modulator are theoretically illustrated through optimizing some sensitive factors such as crystal length, lightwave incident direction, and so on. As a result, it can be used as a useful theoretical guidance for the design and practical utilization of LiNbO 3 crystal electro-optic modulator.

Solar storms in the ionosphere have a great impact on human’ s life. It’s of great significance to find an effective way for an accurate prediction of solar storms. In this paper, we pr esent a method based on GUVI FU V day-glow imaging data to derive O/N 2, an environmental parameter used to forecast Space Weathe r. In the retrieval, we selected two channels of the FUV wavelengths, OI135.6nm and LBH2. In accordance with the linear relationship between O/N 2 and 135.6/LBH, we proposed 135.6/LBH to describe O/N 2 . With the method described in this paper, the data of a 4-day solar storm, October 1 to 4, 2002, have been processed. Subsequently, the obtained O/N 2 maps were in good agreement with previous results. It demonstrated the retrieval process we put up is efficient. Keywords: GUVI, O/N 2 , retrieval technique, 135.6/LBH 1. INTRODUCTION The ionosphere, used for radio communication, directly influences human’s life; its disturbance is mainly induced by solar storms. Therefore, it’s of urgent need to find an accurate way to forecast sola r storms in the ionosphere. When solar storms carrying a large number of particles att ack the atmosphere, it will cause the depletion of O’s number density, while the N

Background subtraction is a method typically used to extract foreground objects in image sequences taken from static cameras by comparing each new frame to a background model, and it plays an important role in many vision application systems. In this paper, we introduce a non-parametric background subtraction method. Standard kernel density estimation method is very time consumptive, so it is modified by substituting the Gaussian kernel function with Epanechnikov kernel function and some optimizing techniques are adopted to improve its performance. As fluctuation is the intrinsic character of infrared image, we develop a bi-threshold updating method and a gradient based post-process method to reduce false positive error. Experiments show our method can extract intruding objects effectively and it outperforms threshold based method, especially when the intruder is not salient.

At present, bidirectional transmission over a signal fiber is applied in many fields, such as WDM. Bidirectional transmission over a signal fiber can reduce the required number of fibers and uses one optical source, so it is lower cost than unidirectional transmission counterparts. In this paper, the phase-noise counteracting characteristic in the bidirectional transmission over a polarization maintaining fiber (PMF) due to different polarization rotating angle of counter-propagation light is analyzed. The analyzing results indicate that the bidirectional system with a special polarization rotating angle of counter- propagation light has a good property that can counteract phase noises coming from external factors such as temperature etc. reciprocal factors. Thus, phases’ fluctuation can be reduced and it has the advantages of measuring phase change and achieving phase calibration. Based on the result, using Jones matrix, the established system is discussed and the phase difference owing to nonreciprocal parameters such as Faraday electromagnetic induction is obtained. So the calibration of phase is achieved according to the measured results.

This paper describes a design of sun-tracking warning demonstration system in solar blind UV. After analyzing of the system structure and guide line of the sun-tracking warning system in solar blind UV, the key techniques of the sun-tracking UV warning system are discussed and designed, including the optical system, UV filter module, optical modulation system, UV detectors and its sun-tracking servo. A total reflect Cassegrain UV optical system with simple structure, reliable performance and high-quality imaging ability is designed and manufactured. In order to enhance the received SNR and process the signal easily, an optical UV filte r and an optical modulation re ticle are used to filter and modulate the target’s direct signals to alternating signal. Functional experiments show that sun-tracking warning system needs better UV filter module whose total stopband rejection should be higher than 10 -10 . Keywords: UV warning, sun-tracking UV warning, solar-blind, optical design, modulation reticle.

A color image database of different scenes under several fixed illuminants is constructed in this paper. It contains images for 45 scenes captured under illumination of various color, lightness. Some analysis based on the database are described to find the relationship between chromatic/lightness distribution of images under different illumination. Indexes as overall mean and SD are introduced, which are reasonable to evaluate image lightness and contrast coordinating to visually representation. In order to objectively assess the influence of illuminant color to images, investigation on lαβand r-g chromatic map are explored. An improved hue correlation method is proposed based on , α βmean/SD statistical analysis, which shows excellent color constancy performance on CPVO measurement. The CPVO measurement is also established on r-g chromatic peak offset tests in this paper.

A practical single-scattering model of solar blind UV communication channel, which is suitable for NLOS digital communication is presented in the paper. NLOS transmission loss of UV channel is deduced by Lambert law . Calculation method of scattering phase function and integral of intersection volume between transmitting beam and receiving beam are described detailed in prolate spheriodal coordinate. Base on them, a practicable calculation method about signal to noise ratio (SNR) and bit error rate (BER) of UV communication systems is presented, which construct a bridge between system parameters and digital system performances in simulation of UV communication channel and systems .Under certain BER and typical modulations in UV communication , relationship between system parameters and system performances are discussed.

Genetically encodable fluorescent biosensors based on fluorescence resonance energy transfer (FRET) are being developed for analyzing spatiotemporal dynamics of various signaling events in living cells, as these events are often dynamically regulated and spatially compartmentalized within specific signaling context. In particular, to investigate the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in the cellular context, we have developed a series of such biosensors that enable dynamic visualization of several key signaling events in this pathway, namely InPAkt for lipid second messenger dynamics, BAKR for Akt activity, and ReAktion for the action of Akt during its multi-step activation process. Discussed here are several studies that have been carried out with these novel biosensors. First, we examined nuclear phosphatidylinositol-3,4,5-triphosphate (PIP3) in living cells using nucleus-targeted InPAkt. Second, we analyzed signal propagation from the plasma membrane to the nucleus by using plasma membrane-targeted InPAkt and nucleus-targeted BKAR to simultaneously monitor PIP3 dynamics and Akt activity in the same cell. Of note, results from these co-imaging experiments suggest that active Akt can dissociate from the plasma membrane and translocate into the nucleus in the presence of high levels of PIP3 at the plasma membrane. This finding has led to a further study of the action of Akt during its activation process, particularly focusing on how Akt dissociates from the membrane. In this regard, a live-cell molecular analysis using ReAktion reveals a conformational change in Akt that is critically dependent on the existence of a phosphorylatable T308 in the activation loop. Subsequently this has led to the discovery of new regulatory roles of this critical phosphorylation event of Akt for ensuring its proper activation and function.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A LOS solar blind UV communication channel model is presented in the paper, which consists of three sections: propagation loss section, scattering transmission section and background noise section. LOS transmission loss model of UV channel is deduced by Lambert law and noise power calculation is also analyzed. Base on them, a practicable calculation method of signal to noise ratio (SNR) is presented, which is a bridge between system parameters and system performances such as BER and limit communication distance in analysis of UV communication. Transmission loss and SNR of LOS are measured in outdoor experiments. The experiment shows that SNR calculation data agree with the experimental results quite well. The calculation also shows that the limit communication distance of LOS can achieve 7kms with the UV sensor at present.

Realistic image rendition, concerning on color constancy and lightness, is usually qualified by subjective evaluation, involving uncertainly psychophysical course. Whether common objective image quality metrics can be adopted to evaluate the rendition results is studied in this paper. Several common objective image quality metrics such as RMES, PSNR, and a newly universal one named Q metric are introduced. Experiments show that it's applicable to take images under standard lighting conditions (e.g. D65) as reference images, which is necessary for objective assessment. Experiment results confirm that introduced objective image quality metrics can help to evaluate the lightness and color constancy ability of images, in case of taking images under standard lights as reference images.

A new sub-pixel interpolation algorithm based on multi-resolution filtering technology is presented in the paper. During the course of the analyzing the algorithm, we theoretically testified the conclusion that the sub pixel imaging technology can improve system image resolution. It can be concluded from the experiment result that the new interpolation algorithm can raise the resolution remarkably. We presented a real-time system based on TI DSP to realize the new algorithm. The sub pixel imaging system is developed with the flexible whole design and modular design so that it has the characteristics of extending, maintainability and easy soft developing.

The definition and classifications of the UV communication are described in the paper. The UV channel consists of three sections: propagation loss section, scattering section and background-noise section. The principle of selecting the wave band of UV communication is analyzed. The LOS and NLOS (a) transmission models are presented, and the two configurations are well proved by outdoor experiments. The experiment results also show that the communication distance of LOS can go up to 5kms, and NLOS(a) can reach 2kms with the UV detectors at present.

The real-time detection and surveillance of space targets are primary functions of space surveillance system. On account of abundant infrared radiation of the electronic and electromechanical equipments inside satellites, spacecraft, etc., the infrared characteristics of space targets will be very obvious in the cold astrospace background. Therefore, using spaceborne IR detection system is very beneficial to space object detection, especially in the absence of any significant atmosphere. The key characteristic of spaceborne IR system is passive measurement principle, but not requiring direct sun illumination. This is very proper for the purposes of space control requirements. This paper has theoretically determined the feasibility of the spaceborne IR detection system in using infrared radiation characteristics of a space object and IR imaging sensor to locate and recognize object. According to the requirements of an IR imaging system to modulation contrast, signal-to-noise ratio (SNR) and image size of space object, the paper has discussed infrared radiation characteristics of space object and background, the structure of the system and primary factors which can affect operation range of the system. Results indicate that such parameters as principal design wavelength, spectral band and pixel size of receiving sensor, focal length and aperture diameter of receiving optics system and so on can determine scale, capacity and practicability of detection system. With a 150mm aperture, 800mm focal distance and 13μm IR CCD imaging pixel dimension, the system could detect a space object with size of 10 m and distance of 200 km. The imaging point of this object would occupy 3×3 pixels point.

A design is described for photoelectric equipment reconnaissance using an active laser detection system based on the 'cat's eyes' effect of optical windows and the technique of non-linear Optical Phase Conjugation (OPC). With 'cat's eyes' effect, the detection of uncooperative target can be translated into one of a cooperative target, so the ratio of returned laser for remote target can be increased. The receiver used for receiving retro-reflection laser employs a laser amplifier, a Phase Conjugating Mirrors (PCM) based on Stimulated Brillouin scattering (SBS), as it allows for compensation of spatial non-uniformity on the laser pass coming from atmospheric turbulence. The system is thus composed of a laser emitter, a laser receiver and an information processing subsystem. The light reflected by the optical window of target acts as the beacon light. The phase conjugate light which is produced by the laser receiver according to the wavefront aberration of the beacon light is emitted to the target, and reflected by the target to the receiver and information processing subsystem separately. This system is capable of sustaining oscillation between target and laser receiver, locks onto a target and then detects its position and velocity accurately.

Considering the fact that the remote sensing image is mainly captured by a linear CCD with the push-broom way which the image varies over time, the time-varying wavelet packets for image restoration is proposed in the paper. On one hand, the result of the method is that the problem of the correlation between the images is solved, and on the other hand, it is the method that can remarkably reduce the calculating overhead and the data throughput, which is a key innovation for a real-time system. In this paper, the optimized wavelet packet bases by double tree searching algorithm are adaptively changed in different time. To realize the algorithm, we presented a dual DSPs real-time parallel system. The parallel system based on TMS320C6416-7E3 DSP has the characteristics of modular and flexible design and maintainability. The ping-pong structure and the streamline structure are both designed in the system. According to the complexity of the algorithm and the requirement of the data throughput, one of the two parallel structures can be realized freely only by changing a bit. It can realize the restoration algorithm with 4096*4096 images in real-time by demonstrated by our experiment in practice.

In order to utilize the multiscale characteristics of wavelet transform more sufficiently, a new adaptive image restoration method using wavelet packets based on the edge detection is presented. The method allows for the decomposition of image signal with various frequencies in the subband domain. The proposed filters in the paper explicitly incorporate both within and between subband relations of the decomposed image. The adaptive filter is used in the approach for considering local adaptation in each subband of the best basis. In order to keep the high frequency information of the image, the adaptive edge detection is presented in the paper. Experimental results, which could test the proposed method, are got. It is found that the proposed method show not only great noise reduction in the processed images but also significant improvement of subjective image quality over the conventional image restoration methods.

A new hardware implementation of histogram equalization by means of Field Programmable Gate Array (FPGA) is presented. Histogram equalization is an effective means of image enhancement. Its real-time processing requires a great deal of memory and very high processing speed. The logic cell nature of XC4000 family's FPGA is most suitable for performing real-time pixel-level image processing operations such as histogram equalization. A core is constructed to complete this histogram statistics and histogram equalization. As a result, the chip makes circuits and system more effective than ever, and it takes very short time to complete the calculation and generate the look-up table. The equalizing technique is described and implementation results using a Xilinx XC4010 FPGA are presented.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Image fusion technique has gradually been paid more and more attention to for its advantage of integration of information from multisensors, and its application has been developed in many fields such as medicine, remote sensing, computer vision, weather forecast, etc. In this paper, some fusion algorithms on pixel level have been programmed and their effects have been analyzed. A new efficient method named after Contrast Modulation-Pyramid Algorithm has been developed. The realization of this new algorithm has been designed and researched with Digital Signal Processor and has been programmed with relevant software. The result showed that image fusion would been completed at real-time or quasi-real-time speed.