2013
2013
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Record 385 of
Title:Visual saliency detection using information divergence
Author(s):Hou, Weilong(1); Gao, Xinbo(1); Tao, Dacheng(2); Li, Xuelong(3)Source: Pattern Recognition Volume: 46 Issue: 10 DOI: 10.1016/j.patcog.2013.03.008 Published: October 2013Abstract:The technique of visual saliency detection supports video surveillance systems by reducing redundant information and highlighting the critical, visually important regions. It follows that information about the image might be of great importance in depicting the visual saliency. However, the majority of existing methods extract contrast-like features without considering the contribution of information content. Based on the hypothesis that information divergence leads to visual saliency, a two-stage framework for saliency detection, namely information divergence model (IDM), is introduced in this paper. The term "information divergence" is used to express the non-uniform distribution of the visual information in an image. The first stage is constructed to extract sparse features by employing independent component analysis (ICA) and difference of Gaussians (DoG) filter. The second stage improves the Bayesian surprise model to compute information divergence across an image. A visual saliency map is finally obtained from the information divergence. Experiments are conducted on nature image databases, psychological patterns and video surveillance sequences. The results show the effectiveness of the proposed method by comparing it with 13 state-of-the-art visual saliency detection methods. ? 2013 Elsevier Ltd. All rights reserved.Accession Number: 20132216369998 -
Record 386 of
Title:Reversal construction of polarization-controlled focusing field with multiple focal spots
Author(s):Wang, Jiming(1,2); Liu, Qingliang(1,3); He, Chongjun(1); Liu, Youwen(1)Source: Optical Engineering Volume: 52 Issue: 4 DOI: 10.1117/1.OE.52.4.048002 Published: April 2013Abstract:We propose an approach to control the polarization and intensity of the focusing field with multiple focal spots in a high-numerical-aperture imaging system. This focused field is explained as the reversal radiation of the dipole array with presupposed oscillating direction in the focal volume. By engineering the structure of the electric dipole array and reversing the radiation from this dipole array, the local manipulation of intensity and polarization in the focal region is achieved, and the required field at the pupil plane is derived. A focusing field with six vectorial focal spots is created as an example to verify this method. This multifocal field will meet potential application in polarization-dependent optical microscope and optical trapping for multiple particles. ? 2013 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20142217763348 -
Record 387 of
Title:Pedestrian detection in unseen scenes by dynamically updating visual words
Author(s):Cao, Xianbin(1); Wang, Li(1); Ning, Bo(2); Yuan, Yuan(3); Yan, Pingkun(3)Source: Neurocomputing Volume: 119 Issue: DOI: 10.1016/j.neucom.2013.03.036 Published: November 7, 2013Abstract:Adapting trained detectors to unseen scenes is a critical problem in pedestrian detection. The performance of trained detector may drop quickly when scenes vary significantly. Retraining a detector with labeled samples from the new scenes may improve its performance. However, it is difficult to obtain enough labeled samples in real applications. In this paper, a novel bag of visual words based method is proposed to detect pedestrians in unseen scenes by dynamically updating the key words. The proposed method achieves its adaptability by using three strategies covering key word selection, detector invariance, and codebook update: (1) In order to select typical words representing pedestrians, a low dimensional model of visual words is built to describe their distribution and select key words using manifold learning. (2) Matching confidence vector (MCV), a novel visual words measurement is proposed, which aims to generate a uniform input vector for the fixed detector applied to different pedestrian codebooks. (3) When detecting pedestrians under changing road conditions, the key word set will be dynamically adjusted according to the matching frequency of each word to adapt the detector to the new scenes. By employing the above strategies, the proposed method is able to detect pedestrians in different scenes without retraining the detector. Experiments in different scenes showed that our proposed method can achieve better adaptability to various scenes and get better performance than other existing methods in unseen scenes. ? 2013 Elsevier B.V.Accession Number: 20133416640460 -
Record 388 of
Title:Energy-saving object detection by efficiently rejecting a set of neighboring sub-images
Author(s):Pan, Jing(1); Pang, Yanwei(2); Zhang, Kun(2); Yuan, Yuan(3); Wang, Kongqiao(4)Source: Signal Processing Volume: 93 Issue: 8 DOI: 10.1016/j.sigpro.2012.08.019 Published: August 2013Abstract:Object detection is crucial for multimedia processing such as image understanding and video analysis. Due to the large amount of images and videos and the limited computational resource, effective and efficient object detection is challenging. Although much effort has been done to develop fast object detection algorithms, little work was concentrated on energy-saving algorithms. Even two detection algorithms that detect objects in the same speed may consume different electronic energies. In this paper, we focus on developing an energy-saving object detection algorithm which can reject a bundle of neighboring sub-images with only one inner-product operation and an acceptable number of addition ones. The total number of multiplications and additions of our algorithm is almost equal to that of the traditional sliding-window method. But in our algorithm the number of multiplication operations is much smaller. Because addition operation consumes less energy than multiplication operation, the proposed method is more energy-saving and efficient. Experimental results on hand detection show that our approach leads to significant improvements in energy and efficiency. ? 2012 Elsevier B.V.Accession Number: 20131716226351 -
Record 389 of
Title:High contrast ballistic imaging using femtosecond optical Kerr gate of tellurite glass
Author(s):Tan, Wenjiang(1); Zhou, Zhiguang(2); Lin, Aoxiang(2); Si, Jinhai(1); Zhan, Pingping(1); Wu, Bin(1); Hou, Xun(1)Source: Optics Express Volume: 21 Issue: 6 DOI: 10.1364/OE.21.007740 Published: March 25, 2013Abstract:We investigated the ballistic imaging technique using femtosecond optical Kerr gate of a tellurite glass. High contrast images of an object hidden behind turbid media were obtained. Compared to the conventional femtosecond optical Kerr gate using fused quartz, the optical Kerr gate using tellurite glass has more capacity to acquire high quality images of the object hidden behind a high optical density turbid medium. The experimental results indicated that the tellurite glass is a good candidate as the optical Kerr material for the ballistic imaging technique due to its large optical nonlinearity. ? 2013 Optical Society of America.Accession Number: 20131516186783 -
Record 390 of
Title:Chirp structure measurement of a supercontinuum pulse based on transient lens effect in tellurite glass
Author(s):Zhang, Hang(1); Zhou, Zhiguang(2); Lin, Aoxiang(2); Cheng, Jun(1); Yan, Lihe(1); Si, Jinhai(1); Chen, Feng(1); Hou, Xun(1)Source: Journal of Applied Physics Volume: 113 Issue: 11 DOI: 10.1063/1.4795587 Published: March 21, 2013Abstract:We demonstrated the controllable acquisition of optical gated spectra from a chirped supercontinuum (SC) pulse based on ultrafast transient lens (TrL) effect. Comparing with CS2, the gated spectra had much narrower spectral bandwidths using tellurite glass (Te glass) as the nonlinear medium due to its ultrafast nonlinear response. Experimental results showed that the chirp structure of the SC pulse measured by TrL method was quite accordant with that measured by femtosecond optical Kerr gate method. ? 2013 American Institute of Physics.Accession Number: 20131516184595 -
Record 391 of
Title:1.23 μm emission of Er/Pr-doped water-free fluorotellurite glasses
Author(s):Zhan, Huan(1,2); Zhang, Aidong(2); He, Jianli(2); Zhou, Zhiguang(2); Si, Jinhai(1); Lin, Aoxiang(2)Source: Applied Optics Volume: 52 Issue: 28 DOI: 10.1364/AO.52.007002 Published: October 1, 2013Abstract:To investigate the relatively unexplored 1.2 μm region, we identified a near-infrared emission at around 1.23 μm from Er3/Pr3-codoped water-free fluorotellurite glass with a composition of 60TeO2-30ZnF2-10NaF (TZNF60, mol. %). Under the condition of pumping with the 488 nm optical parametric oscillator (OPO) laser system, the directly measured lifetime (tf ) at 1.23 μm in Er/Pr-codoped fluorotellurite glasses is about 111.2 μs, much longer than that of Er-doped fluorotellurite glass (80.1 μs). The stimulated emission cross section (sem) and quantum efficiency (?) for Er3:4S3/2 ? 4I11/2 transition are greatly enhanced when appropriate Pr3 ions are incorporated. These advances arise partially from the absence of the hydroxyl (OH) group and low phonon energy with the addition of a large amount of fluorides into oxide-based host glasses. With high quantum efficiency (56.2%) and a large stimulated cross section (4.03 × 10-21 cm2), Er3/Pr3-codoped TZNF60 glass is regarded as promising material for the development of optical amplification and laser operation at the relatively unexplored 1.2 μm region. ? 2013 Optical Society of America.Accession Number: 20134316904279 -
Record 392 of
Title:Experimental study of the damage of silicon photoelectric detector materials induced by repetitively-pulsed femtosecond laser
Author(s):Cai, Yue(1); Ma, Zhi-Liang(1); Zhang, Zhen(1); Cheng, Guang-Hua(2); Ye, Xi-Sheng(1); Cheng, De-Yan(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8796 Issue: DOI: 10.1117/12.2011136 Published: 2013Abstract:The experimental setup was established for studying damage effects on silicon photoelectric detector materials induced by 800nm and 150fs repetitively-pulsed laser. The detector is irradiated by single shot and multiple shots respectively. The laser damage thresholds of silicon photoelectric detector material were measured. The surface morphologies of the material damaged by laser were analyzed. The surfaces damaged by laser with different energy were compared. The thresholds vary with the number of laser shots. According to the accumulation theory, the damage threshold is the power function of the shot number. Experimental results show that threshold of single shot that damages the silicon photoelectric detector is 0.156J/cm2. The laser damage threshold decreases with the increasing number of laser pulses, but the minimum value exists. The damage is mainly caused by the mechanical effect rather than thermal effect. In fact, the thermal effect during the interaction is so small that it can't even be observed. Resistivity of the silicon photoelectric detector irradiated by femtosecond laser decreases and finally tends to a constant value. ? 2013 SPIE.Accession Number: 20133216576134 -
Record 393 of
Title:Femtosecond nonlinear optical property of a TeO2-ZnO-Na 2O glass and its application in time-resolved three-dimensional imaging
Author(s):Tan, Wenjiang(1); Zhou, Zhiguang(2); Lin, Aoxiang(2); Si, Jinhai(1); Tong, Junyi(1); Hou, Xun(1)Source: Optics Communications Volume: 291 Issue: DOI: 10.1016/j.optcom.2012.11.035 Published: March 15, 2013Abstract:Compared with bismuth glasses and chalcogenide glasses, tellurite glasses have a wider transparency window. Especially, these glasses with excellent transparency in visible region could offer a larger dynamic range for the time-resolved simultaneous three-dimensional imaging based on the optical Kerr gate (OKG). We investigated the ultrafast nonlinear optical properties of a TeO2-ZnO-Na2O glass using a femtosecond optical Kerr gate at wavelength of 800 nm. The nonlinear refraction n2 and the ultrafast nonlinear response time of the tellurite glass were estimated to be 4.56×10-15 cm2/W and less than 200 fs, respectively. We also demonstrated the time-resolved simultaneous three-dimensional imaging using the tellurite glass as the Kerr medium, which indicated that tellurite glasses may also be good candidates as the Kerr media for the time-resolved imaging based on the OKG. ? 2012 Elsevier B.V.Accession Number: 20130315912426 -
Record 394 of
Title:High nonlinear fluorotellurite glass fiber
Author(s):Zhan, Huan(1,2,3); Zhang, Aidong(1); He, Jianli(1,2); Shi, Tengfei(1,2); Si, Jinhai(3); Lin, Aoxiang(1)Source: Asia Communications and Photonics Conference, ACP Volume: Issue: DOI: 10.1364/acpc.2013.aw4c.3 Published: 2013Abstract:We report on the fabrication of water-free fluorotellurite glass fiber with high nonlinearity. By the continuous-wave self-phase modulation method, the nonlinear refractive index n2 is estimated to be 1.4×10 -18 m2/W at 1550 nm. ? OSA 2013.Accession Number: 20142017711177 -
Record 395 of
Title:1·23 μm emission of Er-doped water-free fluorotellurite glasses
Author(s):Zhan, Huan(1,2,3); He, Jianli(1); Zhou, Zhiguang(1); Zhang, Aidong(1); Si, Jinhai(2,3); Lin, Aoxiang(1)Source: Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B Volume: 54 Issue: 6 DOI: Published: December 2013Abstract:To identify more efficient materials for 1·2 μm fibre optical amplifiers, we report on near-infrared emission centred at 1·23 μm from Er3+-doped water-free fluorotellurite glasses with the composition 60TeO2-30ZnF2-10NaF (TZNF60, mol%). Pumped by an OPO laser system at 523 nm, emission at 1·23 μm (Er 3+:4S3/2?4I11/2 transition) was observed; the τf at 1·23 μm is 21·6-86·4 μs, arising from the optimized water-free surroundings and lower phonon energy arising from the addition of a large amount of fluoride into the tellurite-based host glass. 0·5 wt% Er 2O3 doped TZNF60 glass is regarded as a promising material for the development of optical amplification and laser operation at the relatively unexplored 1·2 μm region as it has the highest quantum efficiency and the largest figure of merit among this group of Er-TZNF60 glasses.Accession Number: 20140417230240 -
Record 396 of
Title:Femtosecond laser-induced permanent anisotropy in bacteriorhodopsin films and applications in optical data storage
Author(s):Yu, Xianghua(1); Yao, Baoli(1); Lei, Ming(1); Gao, Peng(1); Ma, Baiheng(1)Source: Journal of Modern Optics Volume: 60 Issue: 4 DOI: 10.1080/09500340.2013.774067 Published: February 1, 2013Abstract:In polymeric films of bacteriorhodopsin (BR) a photoconversion product named F540-state, which is excited by 790 nm femtosecond laser pulses, is stable either for photochemical reaction or thermal pathway. The optical properties of the F540-state were studied, and Jones-matrix theory was adopted to analyze the photoinduced anisotropy of the F 540-state. Based on the permanently photoinduced anisotropy, write-once-read-many (WORM) optical data storage was demonstrated by using two polarization states of femtosecond pulsed laser. Since the polarization information is also written on the storage media, it is impossible to copy it in a common way. This storage technique has a potential application in advanced optical security. ? 2013 Copyright Taylor and Francis Group, LLC.Accession Number: 20131616216202