Laser active imaging is widely used in many fields. The intensity image quality of laser active imaging is affected by various degradations, such as speckle effect and noise. Most existing objective image quality assessment (IQA) methods that consider only a single distorted image are not suitable for an intensity image. A multiscale full-reference intensity IQA method is presented. The proposed method is based on an improved gradient magnitude similarity deviation (GMSD) in the nonsubsampled contourlet transform (NSCT) domain. The reference and distorted images are decomposed by NSCT to emulate the multichannel structure of the human visual system. Then, the GMSD of each sub-band is computed to capture the intensity image quality. At last, the contrast sensitivity function implementation is employed in the sub-bands of the NSCT domain. All sub-bands’ GMSD is evaluated and pooled together to yield the objective quality index of a distorted intensity image. Experimental results show that the proposed method can effectively and accurately evaluate the quality of intensity images, and it is highly consistent with subjective perception.
Laser radar is rapidly developing towards very capable sensors for number of applications such as military sensing and
guidance, auto collision avoidance, robotic vision and atmospheric sensing. In this paper, the detection performance of
non-scanned Laser Rang-gated (LRG) imaging system is studied. In order to compute the detection range of laser active
imaging system, the range equation is derived by using laser illuminating model and considering factors which affect
system imaging quality. According to the principle of laser radar and the characters of objects and the detectors in special
applied setting, it mainly deduced the non-scanned laser radar range equation of the range-gated system, meanwhile, the
SNR model of non-scanned LRG imaging system is set up. Then, relationship of the detection probability, the false
alarm probability and the signal-to-noise ratio in the non-scanned LRG imaging system are analyzed, the influence
factors of system's performance are pointed out, and the solution is proposed. The detection performance simulation
software of non-scanned LRG imaging system is designed with MATLAB and the performance of the imaging system is
simulated.
Terahertz (THz) radiation, which occupies a large portion of the electromagnetic spectrum between infrared and microwave bands, offers innovations imaging and sensing technologies that can provide information not available through conventional methods such as microwave, X-ray imaging and NMR(nuclear magnetic resonance). T-ray imaging can give not only the density picture but also the phase information within the frequency domain. T-ray imaging has several advantages over other sensing and imaging techniques, so it has many important scientific, industrial and medical applications. In this paper, we study the feasibility of using THz sensing and imaging for mine detection. The principal features of THz radiation and its unique advantage in mine detection are investigated. Some difficult issues, which are not resolved yet, are discussed. The military applications and development trend of the THz spectroscopy are briefly forecasted.
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