Jufeng Zhao

Optical imaging system-based real-time image saliency extraction method

Abstract. Saliency extraction has become a popular topic in imaging science. One of the challenges in image saliency extraction is to detect the saliency content efficiently with a full-resolution saliency map. Traditional methods only involve computer calculation and thus result in limitations in computational speed. An optical imaging system-based visual saliency extraction method is developed to solve this problem. The optical system is built by effectively implementing an optical Fourier process with a Fourier lens to form two frequency planes for further operation. The proposed method combines optical components and computer calculations and mainly relies on frequency selection with precise pinholes on the frequency planes to efficiently produce a saliency map. Comparison shows that the method is suitable for extracting salient information and operates in real time to generate a full-resolution saliency map with good boundaries.

Tetranuclear iron carbonyl complexes with a central tin atom: relationship to iron carbonyl carbides

The two tetranuclear iron carbonyl systems EFe4(CO)n (E = Sn, C) containing central group 14 interstitial atoms differ in that spiropentane-like SnFe4(CO)16 has been synthesized in the tin system whereas the butterfly CFe4(CO)13, with three fewer carbonyl groups is the carbonyl-richest tetranuclear iron carbonyl carbide that has been synthesized. In order to clarify this point, the complete SnFe4(CO)n (n = 16, 15, 14, 13, 12) series has been studied by density functional theory for comparison with earlier similar studies on their CFe4(CO)n analogues. The experimentally observed spiropentane-like Sn[Fe2(CO)8]2 structure is found to be the lowest energy structure for the SnFe4(CO)16 system as it is for the experimentally unknown CFe4(CO)16 system. Loss of a CO group from Sn[Fe2(CO)8]2 joins the two Fe2(CO)8 units by a third Fe–Fe bond to give an SnFe4(CO)15 structure with a bonded four-atom Fe–Fe–Fe–Fe chain. Further CO loss from SnFe4(CO)15 adds a fourth Fe–Fe bond in the lowest energy SnFe4(CO)14 structure. The lowest energy SnFe4(CO)13 structure is analogous to that of the experimentally known iron carbonyl carbide CFe4(CO)13 with a central Fe4 butterfly having five Fe–Fe bonds. The energetics of CO dissociation from the EFe4(CO)n (E = C, Sn; n = 16, 15, 14, 13) species account for the experimentally observed differences between the systems with central tin and central carbon atoms. Thus for the tin systems the CO dissociation energy from SnFe4(CO)16 is relatively high at ∼50 kcal mol−1 consistent with its experimental observation as a stable species. However, for the tetranuclear iron carbonyl carbides CFe4(CO)n, the CO dissociation energies of the species with more than 13 CO groups are all very small or even negative suggesting CFe4(CO)13 to be the carbonyl-richest viable iron tetracarbonyl carbide consistent with experiment.

A motion deblurring method with long/short exposure image pairs

In this paper, a motion deblurring method with long/short exposure image pairs is presented. The long/short exposure image pairs are captured for the same scene under different exposure time. The image pairs are treated as the input of the deblurring method and more information could be used to obtain a deblurring result with high image quality. Firstly, the luminance equalization process is carried out to the short exposure image. And the blur kernel is estimated with the image pair under the maximum a posteriori (MAP) framework using conjugate gradient algorithm. Then a L0 image smoothing based denoising method is applied to the luminance equalized image. And the final deblurring result is obtained with the gain controlled residual image deconvolution process with the edge map as the gain map. Furthermore, a real experimental optical system is built to capture the image pair in order to demonstrate the effectiveness of the proposed deblurring framework. The long/short image pairs are obtained under different exposure time and camera gain control. Experimental results show that the proposed method could provide a superior deblurring result in both subjective and objective assessment compared with other deblurring approaches.

Fast searching measurement of absolute displacement based on submicron-aperture fiber point-diffraction interferometer

The submicron-aperture fiber point-diffraction interferometer (SFPDI) can be applied to realize the measurement of three-dimensional absolute displacement within large range, in which the performance of point-diffraction wavefront and numerical iterative algorithm for displacement reconstruction determines the achievable measurement accuracy, reliability and efficiency of the system. A method based on fast searching particle swarm optimization (FS-PSO) algorithm is proposed to realize the rapid measurement of three-dimensional absolute displacement. Based on the SFPDI with two submicron-aperture fiber pairs, FS-PSO method and the corresponding model of the SFPDI, the measurement accuracy, reliability and efficiency of the SFPDI system are significantly improved, making it more feasible for practical application. The effect of point-diffraction wavefront error on the measurement is analyzed. The error of pointdiffraction wavefront obtained in the experiment is in the order of 1×10-4λ (the wavelength λ is 532 nm), and the corresponding displacement measurement error is smaller than 0.03 μm. Both the numerical simulation and comparison experiments have been carried out to demonstrate the accuracy and feasibility of the proposed SFPDI system, high measurement accuracy in the order of 0.1 μm, convergence rate (~90.0%) and efficiency have been realized with the proposed method, providing a feasible way to measure three-dimensional absolute displacement in the case of no guide rail.

Local Saliency Extraction for Fusion of Visible and Infrared Images

In this paper, a local saliency extraction-based dual-band image fusion algorithm is proposed. Combing the variable computational windows, the local gray distance is designed for saliency analysis. And saliency map is further obtained by considering spatial weight. For dual-band image fusion, firstly, we design several local windows named different levels, and get the corresponding saliency maps. Secondly, achieve weighted fusion under different levels with saliency maps. Finally, all fused images are compounded into one fused result. According to experimental results, the proposed method could produce a fused image with good visual effect, preserving even enhancing the details effectively. Comparing with other seven methods, both subjective evaluation and objective metric indicate that the proposed algorithm performs best.