Online tracking of deformable objects under occlusion using dominant points

• Michael Brown and Dilip Prasad
• received 03/15/2013; accepted 06/15/2013; posted 06/17/2013; Doc. ID 186769
• [full text: PDF (3438) KB)]
• Abstract: This paper deals with tracking of deformable objects in presence of occlusion using dominant point representation of the boundary contour. A novel non-integral time propagation model for propagating the dominant points is proposed. It uses an initial guess generated from a linear operation and an analytical conjugate gradient approach for online robust learning of the shape deformation and motion model. A scheme is presented to automatically detect and correct the region of large local deformation. In order to deal with occlusion, admissible restrictions on deformation and motion of the object are automatically determined. The proposed method overcomes the need of offline learning and learns the deformation and motion model of the object using very few initial frames of the input video. The performance of the method is demonstrated using varieties of videos of different objects.

Keywords (OCIS):

• (000.4430) General : Numerical approximation and analysis
• (100.0100) Image processing : Image processing
• (100.2960) Image processing : Image analysis
• (100.5010) Image processing : Pattern recognition
• (100.4999) Image processing : Pattern recognition, target tracking

Scattering of a Gaussian Beam by an Elliptical Cylinder using the Vectorial Complex Ray Model

• Keli Jiang, Xiang'e Han, and Kuan Ren
• received 03/29/2013; accepted 06/15/2013; posted 06/17/2013; Doc. ID 188023
• [full text: PDF (733) KB)]
• Abstract: The scattered waves of a shaped beam by an infinite cylinder in far fieldare, stricto sensu, neither cylindrical nor spherical, so the asymptotic form of special functions involved in the theories based on the rigorous solution of Maxwell equations can not be used to evaluate the scattered intensities, even in the most simple case of the Gaussian beam scattering by an infinite circular cylinder. Thus, although there exist theories for the scattering of shaped beam by infinite cylinders with circular and elliptical sections, the numerical calculations are limited to near field. The Vectorial Complex Ray Model (VCRM) developed by Ren et al describes waves by rays with a new property - the curvature of the wavefront. It is suitable to deal with the scattering of an arbitrarily shaped beam by a particle with smooth surface of any form. In this paper we apply this method to, the scattering of anelliptical cylinder illuminated by a Gaussian beam at normal incidence with arbitrary position and orientation relative to the symmetric axis of the elliptical section of the cylinder. The method for calculating the curvature of an arbitrary surface is given and applied in the determination of the two curvature radii of the Gaussian beam wavefront curvature at any point. Scattering intensities for different parameters of the beam and the particle as well as observation distance are presented to reveal the scattering properties and new phenomena observed in the beam scattering by an infinite elliptical cylinder.

Keywords (OCIS):

• (080.0080) Geometric optics : Geometric optics
• (260.3160) Physical optics : Interference
• (290.5850) Scattering : Scattering, particles
• (080.1753) Geometric optics : Computation methods
• (140.3295) Lasers and laser optics : Laser beam characterization
• (290.5825) Scattering : Scattering theory

Moving Target Detection in Thermal Infrared Imagery using Spatiotemporal Information

• Aparna Akula, Ripul Ghosh, Satish Kumar, and H K Sardana
• received 03/08/2013; accepted 06/13/2013; posted 06/17/2013; Doc. ID 186598
• [full text: PDF (2532) KB)]
• Abstract: An efficient target detection algorithm for detecting moving targets in infrared imagery using spatiotemporal information has been presented. The output of the spatial processing serves as input to the temporal stage in a layered manner. The spatial information is obtained using joint space - spatial frequency distribution and Rényi entropy. Temporal information is incorporated using background subtraction. By utilizing both spatial and temporal information it was observed that the proposed method could achieve both high detection and low false alarms. The method has been validated with 18 sequences of experimentally generated data consisting of a variety of moving targets. Experimental results have shown the high accuracy of the proposed algorithm with an average F-measure of 0.9785.

Keywords (OCIS):

• (100.2000) Image processing : Digital image processing
• (100.2960) Image processing : Image analysis
• (110.3080) Imaging systems : Infrared imaging

Comparison of the Performance of Inverse Transformation Methods from OSA-UCS to CIEXYZ

• Renbo Cao, H. Joel Trussell, and Renzo Shamey
• received 04/19/2013; accepted 06/12/2013; posted 06/14/2013; Doc. ID 189143
• [full text: PDF (1622) KB)]
• Abstract: The Optical Society of America’s Uniform Color Scales (OSA-UCS) is one of the color spaces that most closely approximate a 'true' uniform color space. Different techniques have been used to convert OSA-UCS based color specification parameters, L, j and g, to the CIE tristimulus values, X, Y and Z. However, none of these methods provides a direct method of inverting OSA-UCS to CIEXYZ values. Thus, numerical algorithms, such as Newton-Raphson method, have been employed to obtain the transformations. The relative low accuracy and long computation time of these methods make them undesirable for practical applications. An artificial neural network (ANN) was employed to convert OSA-UCS to CIEXYZ and its performance was compared with that of numerical methods. After optimization, ANN gave a better performance with a mean error (ΔEXYZ) of 1.0×10-4 and a conversion time of less than one second for 1891 samples.

Keywords (OCIS):

• (200.4260) Optics in computing : Neural networks
• (330.1730) Vision, color, and visual optics : Colorimetry
• (350.6980) Other areas of optics : Transforms

Improving Wavefront Reconstruction Accuracy by Using Integration Equations with Higher-Order Truncation Errors in Southwell Geometry

• Guanghui Li, Yanqiu Li, Ke Liu, Xu Ma, and Hai Wang
• received 03/04/2013; accepted 06/11/2013; posted 06/12/2013; Doc. ID 186329
• [full text: PDF (4040) KB)]
• Abstract: It is considered that the applications of integration equations (IEs) with smaller truncation errors (TEs) in wavefront reconstruction will improve reconstruction accuracy. This paper proposes a general method based on Taylor theorem to derive all kinds of IEs in Southwell model. The IE with smaller TE is the one of higher-order. This method can deduce the IE used in Southwell’s reconstruction algorithm, whose TE is the 3rd order of two adjacent estimated points’ interval. Applying the method, we further deduce two IEs with TEs of 5th order and one IE with TE of 7th order. Three reconstruction algorithms corresponding to these three IEs are formulated. A series of simulations demonstrate the validity of applying IEs with higher-order TEs in improving reconstruction accuracy.

Keywords (OCIS):

• (010.7350) Atmospheric and oceanic optics : Wave-front sensing
• (100.5070) Image processing : Phase retrieval
• (220.4840) Optical design and fabrication : Testing

A Simple Solution to the Fresnel-Kirchoff Diffraction Integral for Application to Refraction-Enhanced Radiography

• J. Koch, O. Landen, L. Suter, and L. Masse
• received 03/20/2013; accepted 06/10/2013; posted 06/11/2013; Doc. ID 187237
• [full text: PDF (455) KB)]
• Abstract: We present a simple solution to the Fresnel-Kirchoff diffraction integral that is appropriate for x-ray radiography of strongly absorbing and phase-shifting objects in the geometrical optics regime, where phase contrast enhancements can be considered to be caused by refraction by a semi-opaque object. We demonstrate its accuracy by comparison to brute-force numerical raytrace and diffraction calculations of a representative simulated object, and show excellent agreement for spatial scales corresponding to Fresnel numbers greater than unity. The result represents a significant improvement over approximate formulas typically used in analysis of refraction-enhanced radiographs, particularly for radiography of transient phenomena in objects that strongly refract and show significant absorption.

Keywords (OCIS):

• (050.1960) Diffraction and gratings : Diffraction theory
• (100.5070) Image processing : Phase retrieval
• (110.1650) Imaging systems : Coherence imaging
• (110.2990) Imaging systems : Image formation theory
• (110.7440) Imaging systems : X-ray imaging

Non-Quadratic Penalization Improves Near Infrared Diffuse Optical Tomography

• Ravi Prasad Jagannath and Phaneendra Yalavarthy
• received 03/20/2013; accepted 06/10/2013; posted 06/10/2013; Doc. ID 187491
• [full text: PDF (1180) KB)]
• Abstract: A new frame-work that can easily incorporate any generic penalty function is introduced for performing the diffuse optical image reconstruction procedure. The penalty functions that were used include, quadratic ($\ell_2$), absolute ($\ell_1$), Cauchy, and Geman-McClure. The regularization parameter in each of these cases were obtained automatically using the general cross-validation (GCV) method. The reconstruction results were systematically compared with each other via utilization of quantitative metrics, such as contrast resolution and contrast-to-noise ratio. The reconstruction results indicate that while quadratic penalty may be able to provide better separation between two closely spaced targets, it's contrast recovery capability is limited and the sparseness promoting penalties, such as $\ell_1$, Cauchy, Geman-McClure have better utility in reconstructing high-contrast and complex-shaped targets with Cauchy penalty being the most optimal one.

Keywords (OCIS):

• (100.3010) Image processing : Image reconstruction techniques
• (100.3190) Image processing : Inverse problems
• (170.0110) Medical optics and biotechnology : Imaging systems
• (170.0170) Medical optics and biotechnology : Medical optics and biotechnology
• (170.3010) Medical optics and biotechnology : Image reconstruction techniques
• (170.5280) Medical optics and biotechnology : Photon migration
• (170.6960) Medical optics and biotechnology : Tomography

Image reconstruction of fluorescent molecular tomography based on the simplified matrix system

• Wei Zou, Jiajun Wang, and David Feng
• received 02/19/2013; accepted 06/10/2013; posted 06/10/2013; Doc. ID 185546
• [full text: PDF (948) KB)]
• Abstract: Fluorescent molecular tomographic image reconstruction usually involves repeatedly solving large-scale matrix equations, which are computationally expensive. In this paper, a new method is proposed to reduce the scale of the matrix system. The Jacobian matrix is simplified by deleting the columns or the rows whose values are smaller than a threshold. Furthermore, the measurement data are divided into two groups and are used for iteration of image reconstruction in turn. The simplified system is then solved in wavelet domain to further accelerate process of solving the inverse problem. Simulation results demonstrate that the proposed method can significantly speed up the reconstruction process with the high quality of reconstruction.

Keywords (OCIS):

• (100.3190) Image processing : Inverse problems
• (170.3010) Medical optics and biotechnology : Image reconstruction techniques
• (170.3880) Medical optics and biotechnology : Medical and biological imaging
• (170.6960) Medical optics and biotechnology : Tomography
• (260.2510) Physical optics : Fluorescence

Echelette optical low-pass filter as a Bangerter filter for diagnosis and treatment of amblyopia and diplopia

• Yuriy Borodin, Viacheslav Petrov, and Anatoliy Lapchuk
• received 02/20/2013; accepted 06/10/2013; posted 06/10/2013; Doc. ID 185713
• [full text: PDF (4132) KB)]
• Abstract: A structure consisting from two echelette grating is analyzed for using as optical low pass filter with large dynamic range for medicine - Bangerter filters (BF). The numerical analysis has shown that echelette type Bangerter filters has several advantage over modern optical low pass filter (rectangular BF) using in medicine. Four echelette BFs with different grating periods and one rectangular BF were manufactured. The image blurring in optical visual system with echelette BF is experimentally investigated. Experimentally measured the modulation transfer function (MTF) and line spread function (LSF) demonstrated definite image-blurring (line extension), which is inversely proportional to the width of the grating period. In contrast, the LSF of the rectangular BF has three narrow lines with a small amount of image-blurring (small line extension).The results of measuring the angular visual acuity of the echelette BF coincide well with the results obtained by theory.

Keywords (OCIS):

• (050.1950) Diffraction and gratings : Diffraction gratings
• (170.4580) Medical optics and biotechnology : Optical diagnostics for medicine

Role of intensity fluctuations in third-order correlation double-slit interference of thermal light

• Xi-Hao Chen, Wen Chen, Shao-Ying Meng, Wei Wu, Ling-An Wu, and Guang-Jie Zhai
• received 06/03/2013; accepted 06/10/2013; posted 06/14/2013; Doc. ID 191675
• [full text: PDF (328) KB)]
• Abstract: A third-order double-slit interference experiment with pseudo-thermal light source in the high-intensity limit has been performed by actually recording the intensities in three optical paths. It is shown that not only can the visibility be dramatically enhanced compared to the second-order case as previously theoretically predicted and shown experimentally, but also that the higher visibility is a consequence of the contribution of third-order correlation interaction terms, which is equal to the sum of all contributions from second-order correlation. It is interesting that, when the two reference detectors are scanned in opposite directions, negative values for the third-order correlation term of the intensity fluctuations may appear. The phenomenon can be completely explained by the theory of classical statistical optics, and is the first concrete demonstration of the influence of the third-order correlation terms.

Keywords (OCIS):

• (030.6600) Coherence and statistical optics : Statistical optics
• (100.0100) Image processing : Image processing
• (270.0270) Quantum optics : Quantum optics

Secondary source of quantum or classical partially polarized states

• F. De Zela
• received 05/14/2013; accepted 06/07/2013; posted 06/18/2013; Doc. ID 190428
• [full text: PDF (295) KB)]
• Abstract: A simple device is presented that serves as a secondary source oflight with prescribed polarization properties. The techniqueemployed is based on the Schmidt purification of a mixed quantumstate. Such a purification can be applied to quantum and toclassical polarization states. The device presented here can beused with both classical and quantum primary sources of light. Itallows controlling the degree of polarization as well as theStokes vector that enters the decomposition of a light beam in afully unpolarized and a fully polarized component.

Keywords (OCIS):

• (230.5440) Optical devices : Polarization-selective devices
• (260.3160) Physical optics : Interference
• (260.5430) Physical optics : Polarization

2D Airy-like beam generation by coupling waveguides

• Hongchang Deng and Libo Yuan
• received 05/09/2013; accepted 06/05/2013; posted 06/05/2013; Doc. ID 189997
• [full text: PDF (1913) KB)]
• Abstract: We propose and demonstrate a 2D Airy-like beam generation technique based on arrayed waveguide. We show that the output beams with quasi-Airy amplitude and cubic-like phase from arrayed waveguide end have 2D Airy-like patterns. These beams have abilities to remain quasi-nondiffracting, transverse accelerating and self-healing during propagation. We also analyze wave propagation along this arrayed waveguide using coupled-mode theory and beam propagation method. The numerical results are in good agreement with theoretical prediction.

Keywords (OCIS):

• (130.2790) Integrated optics : Guided waves
• (220.0220) Optical design and fabrication : Optical design and fabrication

Engineering parabolic beams with dynamic intensity profiles

• Adrian Ruelas, Servando Lopez-Aguayo, and Julio Gutierrez-Vega
• received 04/19/2013; accepted 06/04/2013; posted 06/10/2013; Doc. ID 189059
• [full text: PDF (4061) KB)]
• Abstract: We present optical fields formed by superposing nondiffracting parabolic beams with distinct longitudinal wave-vector components, generating light profiles that display intensity fluxes following parabolic paths in the transverse plane. Their propagation dynamics vary depending on the physical mechanism originating interference, where the possibilities include constructive and destructive interference between traveling parabolic beams, interference between stationary parabolic modes, and combinations of these. The dark parabolic region exhibited by parabolic beams permits a straightforward superposition of intensity fluxes allowing formation of a variety of profiles which can exhibit circular, elliptic and other symmetries.

Keywords (OCIS):

• (050.1940) Diffraction and gratings : Diffraction
• (350.5500) Other areas of optics : Propagation

Theoretical analysis and experimental verification of six-step spatial phaseshifting shearing interferometry by double gratings

• Zhen-yan Guo, Yang Song, Jia Wang, Zhen-hua Li, and An-zhi He
• received 03/11/2013; accepted 06/04/2013; posted 06/18/2013; Doc. ID 186764
• [full text: PDF (1575) KB)]
• Abstract: In order to measure the phase projection in moiré tomography, in this paper, we present a new spatial phase-shifting shearing interferometry which only consists of a crossed grating and a linear grating. With it six phase-shifted interferograms can be acquired simultaneously. The intensity distributions of these six interferograms are derived based on the scalar diffraction theory. Analytical results indicate that phase shifts are symmetrically and consistently distributed in the vertical and horizontal directions. Moreover, phase-shift values depend primarily on the parameters of the optical structure. Our results are useful for extracting the phase information of flow fields in moiré tomography.

Keywords (OCIS):

• (050.1960) Diffraction and gratings : Diffraction theory
• (050.5080) Diffraction and gratings : Phase shift
• (100.5070) Image processing : Phase retrieval
• (100.6950) Image processing : Tomographic image processing
• (120.2650) Instrumentation, measurement, and metrology : Fringe analysis
• (120.3180) Instrumentation, measurement, and metrology : Interferometry

Statistical Quantification of the Effects of Viewing Distance on Texture Perception

• Liang Li, Akira Asano, Chie Asano, and Katsunori Okajima
• received 10/22/2012; accepted 06/02/2013; posted 06/04/2013; Doc. ID 178448
• [full text: PDF (2470) KB)]
• Abstract: In general, viewers are more attracted to local features in images at a shorter viewing distance and to global features in images at a longer viewing distance.However, numerical analysis of the effect of viewing distance on human textureperception and how the perception of global and local changes under certain conditions are still undetermined.In this paper, we present statistical prediction of the relationship between the domination ratio of global and local features and the viewing distances under the control of several factors, using logistic regression model.We synthesized textures by separately controlling global andlocal textural features using a texture model based onmathematical morphology, namely the Primitive, Grain, and Point Configuration (PGPC) texture model.Visual sensory tests were carried out on 80 subjects during two sets ofexperiments. The collected data were statistically analyzed using logistic regression and Akaike information criteria.Besides the main factor of viewing distance, the factors including gender, changing the order of viewing positions, and prior knowledge were also shown quantitatively to have significant influence onhuman texture perception. Our results showed that(1) local features of a texture were more attractive to females than males,(2) the first impression might have affected subsequent decisions in texture perception, and(3) subjects who had prior knowledge (supervised) were more sensitive to the changes in global and local dominance.(4) as the interactions of the factors, prior knowledge reduced the effects of individual differences and perception condition differences on human texture perception.This study is dedicated to the construction of numerical relationship between viewing distance and humantexture perception as well as to cognitive investigation of biases in global and local perceptions.

Keywords (OCIS):

• (330.5000) Vision, color, and visual optics : Vision - patterns and recognition
• (330.5020) Vision, color, and visual optics : Perception psychology

Rigorous analytical modeling of high-aperture focusing through a spherical interface

• Thanh Xuan Hoang, Xudong Chen, and Colin Sheppard
• received 04/17/2013; accepted 05/31/2013; posted 06/04/2013; Doc. ID 189019
• [full text: PDF (525) KB)]
• Abstract: High-aperture focusing through a spherical interface has been employed in optical data storage, photolithography, and especially microscopy. This paper first forms an approximate model, based on geometrical optics and Fourier optics, for evaluating focal fields of the focusing systems. This approximatemodel helps to clarify some doubts existing in literature. We then propose arigorous model that is applicable to more general systems. Our model is basedon multipole theory, which expands the electromagnetic fields into sphericalharmonics.

Keywords (OCIS):

• (080.1510) Geometric optics : Propagation methods
• (110.0180) Imaging systems : Microscopy
• (180.0180) Microscopy : Microscopy
• (290.4020) Scattering : Mie theory
• (290.2558) Scattering : Forward scattering
• (070.7345) Fourier optics and signal processing : Wave propagation

Propagation equation of Hermite-Gauss beams through a complex optical system with apertures and its application to focal shift

• Sun Peng, Guo Jin, and Wang Tingfeng
• received 05/02/2013; accepted 05/31/2013; posted 05/31/2013; Doc. ID 189897
• [full text: PDF (408) KB)]
• Abstract: Based on the generalized Huygens-Fresnel diffraction integral(Collins’ formula), the propagation equation of Hermite-Gauss beams through a complex optical system with limiting aperture is derived. The elements of the optical system may be all those characterized by an ABCD ray-transfer matrix, as well as any kind of apertures represented by complex transmittance functions. To obtain the analytical expression, we expand the aperture transmittance function into a finite sum of complex Gaussian functions. Thus the limiting aperture is expressed as a superposition of a series of Gaussian-shaped limiting apertures. The advantage of this treatment is that we can treat almost all kinds of apertures in theory. As application, we define the width of beam and the focal plane using an encircled-energy criterion, and calculate the intensity distribution of Hermite-Gauss beams at the actual focus of a circular aperture-lens.

Keywords (OCIS):

• (050.1970) Diffraction and gratings : Diffractive optics
• (260.1960) Physical optics : Diffraction theory
• (070.7345) Fourier optics and signal processing : Wave propagation

A unified account of gloss and lightness perception in terms ofgamut relativity

• Tony Vladusich
• received 01/03/2013; accepted 05/31/2013; posted 06/11/2013; Doc. ID 182344
• [full text: PDF (3266) KB)]
• Abstract: A recently introduced computational theory of layered surface representation, termed gamut relativity, overturns the classical assumption that brightness, lightness and transparency constitute perceptual dimensions corresponding to the physical dimensions of luminance, reflectance and transmittance, respectively. Here I extend the theory to show how gloss perception can be understood as a product of the layered representation of achromatic surface colors and specular highlights, rather than as a perceptual dimension corresponding to specular reflectance. The theory simulates the effect of image histogram skewness on gloss/lightness ratings and the invariance of lightness as a function of specular highlight intensity, explains the representation of `metallic' surface colors, and reveals a remarkable computational symmetry between glossy and transparent surface colors. Gamut relativity replaces the computational goal of estimating absolute values along putative perceptual dimensions ('inverse optics') with the more attainable goal of parsing the retinal image into layered representations indicative of relative surface and illumination properties.

Keywords (OCIS):

• (330.1720) Vision, color, and visual optics : Color vision
• (330.4060) Vision, color, and visual optics : Vision modeling
• (330.5020) Vision, color, and visual optics : Perception psychology

Iterative, backscatter-analysis algorithms for increasing transmission and focusing light through a highly-scattering random media

• Curtis Jin, Raj Rao Nadakuditi, Eric Michielssen, and Stephen Rand
• received 03/15/2013; accepted 05/21/2013; posted 05/29/2013; Doc. ID 187094
• [full text: PDF (811) KB)]
• Abstract: Scattering hinders the passage of light through random media and consequently limits the usefulness of optical techniques for sensing and imaging. Thus, methods for increasing the transmission of light through such random media are of interest.Against this backdrop, Dorokhov, Pendry and others theoretically predicted the existence of a few highly transmitting eigen-wavefronts with transmission coefficients close to one in strongly backscattering random media. The breakthrough experiments of Vellekoop and Mosk confirmed the existence of these highly transmitting eigen-wavefronts and demonstrated that they could be discovered by using information from the far side of the scattering medium.Here, we numerically analyze this phenomenon in 2-D with fully spectrally accurate simulators and provide rigorous numerical evidence confirming the existence of these highly transmitting eigen-wavefronts in random media composed of hundreds of thousands of non-absorbing scatterers.We then develop physically realizable algorithms for increasing the transmission through random media using backscatter analysis. We show via numerical simulations that the algorithms converge rapidly, yielding a near-optimum wavefront in just a few iterations. We also develop an algorithm that combines the knowledge of these highly transmitting eigen-wavefronts obtained from backscatter analysis with intensity measurements at a point to produce a focus using significantly fewer measurements.

Keywords (OCIS):

• (030.6600) Coherence and statistical optics : Statistical optics
• (290.5825) Scattering : Scattering theory

Nonlocal optical effects on the Goos-Hänchen shift at an interface of a composite material of metallic nanoparticles

• J. H. Huang and P. Leung
• received 05/02/2013; accepted 05/14/2013; posted 05/24/2013; Doc. ID 189898
• [full text: PDF (660) KB)]
• Abstract: We present a theoretical study on the nonlocal optical effects on the Goos-Hänchen (GH) shift of reflected light from a composite material of metallic nanoparticles (MNP). Using different nonlocal effective medium models, it is observed that such effects can be significant for small MNP of sizes down to a few nanometers. For small metallic volume fractions, the composite behaves like dielectric and the nonlocal effects lead to significant different Brewster angles at which large negative GH shifts take place. For larger volume fractions or shorter wavelengths, the composite behaves more like metals and the nonlocal effects also lead to different Brewster angles but at values close to grazing incidence. These results will have significant implications in the application of different effective medium models for the characterization of these nano metallic composites when the MNP’s are down to a few nanometers in size.

Keywords (OCIS):

• (120.5700) Instrumentation, measurement, and metrology : Reflection
• (240.0240) Optics at surfaces : Optics at surfaces
• (260.2110) Physical optics : Electromagnetic optics
• (260.2065) Physical optics : Effective medium theory
• (260.2710) Physical optics : Inhomogeneous optical media