Computer Optics

705-713

Authors: L.L. Doskolovich, A.A. Mingazov, D.A. Bykov, E.A. Bezus

A problem of calculating a refractive surface that forms a required irradiance distribution in the far field in the case of a plane illuminating beam is considered. We show that this problem can be formulated as a mass transportation problem. The specific form of the cost function for this problem is obtained. It is shown that with a certain choice of coordinates, the cost function becomes quadratic. The resulting mass transportation problem also describes a problem of calculating a mirror, which can be considered as a special case of the problem of calculating a refractive surface.

723-734

Authors: A.V. Volyar, M.V. Bretsko, Ya.E. Akimova, Yu.A. Egorov, V.V. Milyukov

Transformations of the vortex beams structure subjected to sectorial perturbation were theoretically and experimentally studied. The analysis was based on computing (measuring) the vortex spectrum that enables us to find the orbital angular momentum (OAM) and Shannon entropy (informational entropy). We have revealed that, in the general case, the number of vortices caused by an external perturbation is not related to the topological charge. For arbitrary perturbation, the topological charge remains equal to the initial topological charge of the unperturbed vortex beam. Growth of the vortex number induced by perturbations is associated with the optical uncertainty principle between the sectorial angle and the OAM. The computer simulation has shown that OAM does not depend on the number of vortices induced by perturbations. Moreover, two maxima are formed both in the positive and negative regions of the vortex spectrum. As a result, the OAM does not practically change in a wide range of perturbation angles from 0 to 90 °. However, at large perturbation angles, when the energy is almost equally redistributed between the vortex modes with opposite signs of the topological charge, the OAM rapidly decreases. At the same time, the Shannon entropy monotonically increases with growing perturbation angle. This is due to the fact that the entropy depends only on the number of vortex states caused by external perturbations.

741-746

Authors: B. Sokolenko, N. Shostka, O. Karakchieva, A.V. Volyar, D. Poletayev

In present paper we propose easy way to implement method of interfering vortices with opposite topological charge for the real time determination of the thickness and information about the surface of studied samples with the resolution up to 7 nanometers. The determination of the characteristics of the medial cross-section of submicron-objects becomes possible due to phase sensitivity of interfering singular beams to the slightest changes in the optical path difference between them. The dependence of rotational angle of resulting interference pattern in case of different sample thickness for two singular beams superposition is considered in detail.

756-764

Authors: S.N. Khonina, K.N. Tukmakov, S.A. Degtyarev, A.S. Reshetnikov, V.S. Pavelyev, B.A. Knyazev, Yu.Yu. Choporova

A silicon subwavelengh terahertz axicon has been designed, fabricated, and investigated by methods of numerical and optical experiments. The research has been performed on a free-electron laser workstation NOVOFEL (Budker Institute of Nuclear Physics of SB RAS, Novosibirsk). Diffractive and polarization features of realized element have been investigated.

773-779

Authors: S.P. Murzin, M.V. Blokhin

Experimental studies of shaping a CO2 laser beam with a reflective diffractive optical element have been performed. To increase the aperture of the initial beam, we used a collimator containing a system of two plane-convex spherical ZnSe lenses. For the focal line formed with the diffractive optical element in combination with the collimator, in addition to a 1.3-fold increase in the length, a decrease in the maximum beam power density was found to occur in the laser spot. It was demonstrated that under the laser action it is possible to generate in a two-phase steel sample regions of full hardening, selective hardening, and annealing, alongside the initial structure. The formation of such structures is due to the distribution pattern of temperature fields and a difference in the cooling rate across the volume of the heat affected zone.

789-795

Authors: V.S. Vasilev, R.V. Skidanov, S.V. Ganchevskaya

We consider the possibility of using generalized lenses in imaging optical systems. We propose using two generalized lenses in a system similar to a Fourier-correlator to obtain a point-to-point mapping, where the second lens is set so that a plane wave is also formed at the output of the system when the incident wave is plane. We show that for generalized lenses with a small deviation of their degree from 2, such a system forms a fairly high-quality image. We use a standard radial photographic chart to test the system, which allows us to determine its key optical characteristics.

803-809

Authors: М.P. Kalaev, А.М. Telegin, K.E. Voronov, Jiang Lixiang, Jiao Jilong

The paper describes a DF-OPTICS device that the present authors designed for the experimental study of changes in the optical properties of a glass whose surface is exposed to high-speed flows of micron-sized dust particles. The device allows the scattering indicatrix and the spectral transmittance to be automatically measured at each point of the sample with a 0.5-mm increment. Advantages of the developed device include small dimensions and the ability to work in vacuum, allowing it to be used in an accelerator chamber to simulate outer space factors. Experimental results for the K-8 glass put in a microparticle accelerator and bombarded by an aluminum powder PAP-1 with a characteristic size of 1-3 µm and speeds of 2-8 km / s are presented. The device makes it possible to measure the change of the spectral transmittance of transparent materials in the UV and RGB regions with an accuracy of 0.005%, which exceeds the sensitivity of some known spectrophotometers.

818-824

Authors: V.V. Arlazarov, K. Bulatov, T. Chernov, V.L. Arlazarov

A lot of research has been devoted to identity documents analysis and recognition on mobile devices. However, no publicly available datasets designed for this particular problem currently exist. There are a few datasets which are useful for associated subtasks but in order to facilitate a more comprehensive scientific and technical approach to identity document recognition more specialized datasets are required. In this paper we present a Mobile Identity Document Video dataset (MIDV-500) consisting of 500 video clips for 50 different identity document types with ground truth which allows to perform research in a wide scope of document analysis problems. The paper presents characteristics of the dataset and evaluation results for existing methods of face detection, text line recognition, and document fields data extraction. Since an important feature of identity documents is their sensitiveness as they contain personal data, all source document images used in MIDV-500 are either in public domain or distributed under public copyright licenses. The main goal of this paper is to present a dataset. However, in addition and as a baseline, we present evaluation results for existing methods for face detection, text line recognition, and document data extraction, using the presented dataset.

833-845

Authors: K.S. Sarin, I.A. Hodashinsky

Handwritten signature verification is an important research area in the field of person authentication and biometric identification. There are two known methods for handwriting signature verification: if it is possible to digitize the speed of pen movement, then verification is said to be on-line or dynamic; otherwise, when only an image of handwriting is available, verification is said to be off-line or static. It is proved that when using dynamic verification, a greater accuracy is achieved than when using static verification. In the present work, the amplitudes, frequencies, and phases of the harmonics extracted from the signature signals of the X and Y coordinates of the pen movement using a discrete Fourier transform are used as characteristics of the signature. All signals are pre-processed in advance, including the elimination of gaps, the elimination of the angle of inclination, the normalization of position and scaling. A fuzzy classifier is proposed as a signature verification tool based on the features obtained. The work examines the effectiveness of this tool in the ensemble, as well as using a procedure for feature selection. To build an ensemble of classifiers, a well-known bagging method is used, and the feature selection is based on the determination of mutual information between a feature and a class of an object. Experiments on signature verification on the SVC2004 data set with the construction of a fuzzy classifier and ensembles of three, five, seven and nine fuzzy classifiers were conducted. Experiments were carried out both with the use of the feature selection procedure and without selection. The efficiency of the classifiers constructed is compared with each other and with known analogues: decision trees, support vector machines, discriminant analysis and k-nearest neighbors.

857-868

Authors: N.I. Chervyakov, P.A. Lyakhov, N.N. Nagornov, M.V. Valueva, G.V. Valuev

Modern convolutional neural networks architectures are very resource intensive which limits the possibilities for their wide practical application. We propose a convolutional neural network architecture in which the neural network is divided into hardware and software parts to increase performance and reduce the cost of implementation resources. We also propose to use the residue number system in the hardware part to implement the convolutional layer of the neural network for resource costs reducing. A numerical method for quantizing the filters coefficients of a convolutional network layer is proposed to minimize the influence of quantization noise on the calculation result in the residue number system and determine the bit-width of the filters coefficients. This method is based on scaling the coefficients by a fixed number of bits and rounding up and down. The operations used make it possible to reduce resources in hardware implementation due to the simplifying of their execution. All calculations in the convolutional layer are performed on numbers in a fixed-point format. Software simulations using Matlab 2017b showed that convolutional neural network with a minimum number of layers can be quickly and successfully trained. Hardware implementation using the field-programmable gate array Kintex7 xc7k70tfbg484-2 showed that the use of residue number system in the convolutional layer of the neural network reduces the hardware costs by 32.6% compared with the traditional approach based on the two’s complement representation. The research results can be applied to create effective video surveillance systems, for recognizing handwriting, individuals, objects and terrain.

886-900

Authors: Yu.V. Vizilter, V.S. Gorbatsevich, S.Y. Zheltov

A general approach to a structure-functional analysis and synthesis (SFAS) of deep neural networks (CNN). The new approach allows to define regularly: from which structure-functional elements (SFE) CNNs can be constructed; what are required mathematical properties of an SFE; which combinations of SFEs are valid; what are the possible ways of development and training of deep networks for analysis and recognition of an irregular, heterogeneous data or a data with a complex structure (such as irregular arrays, data of various shapes of various origin, trees, skeletons, graph structures, 2D, 3D, and ND point clouds, triangulated surfaces, analytical data descriptions, etc.) The required set of SFE was defined. Techniques were proposed that solve the problem of structure-functional analysis and synthesis of a CNN using SFEs and rules for their combination.

517-527

Authors: Volyar A.V., Bretsko M.V., Akimova Ya.E., Egorov Yu.A.

The article examines physical mechanisms responsible for shaping the vortex avalanche induced by a weak perturbation of the holographic lattice of a combined vortex beam. For this, we have developed a new technique for measuring the degenerate spectra of optical vortices and orbital angular momentum of combined singular beams. The technique is based on measuring the intensity moments of higher orders of a beam containing vortices with both positive and negative topological charges. The appropriate choice of the mode amplitudes in the combined beam enables us to form orbital angular momentum anomalous spectral regions in the form of resonance dips and bursts. Since the intensity moments of a vortex mode with positive and negative topological charges are the same (the moments are degenerate) for an axially symmetric beam, the measurements are carried out in the plane of the double focus of a cylindrical lens. The calibration measurements show that the experimental error is not higher than 4.5 %. We also reveal that the dips and bursts in the orbital angular momentum spectrum are caused by the vortex avalanche induced by weak perturbations of the holographic grating relief responsible for the beam shaping. The appearance of the orbital angular momentum dips or bursts is controlled by the relation between the energy fluxes in the vortex avalanche with positive or negative topological charges.

535-543

Authors: Morozov O.G., Sakhabutdinov A.J.

The article describes the theory and technique of addressed fiber Bragg structures and a new class of microwave-photonic sensory systems based thereon, the distinctive feature of which is that the fiber Bragg structure forms two ultra-narrowband frequency components separated by a unique address frequency spacing. The offset of the central frequencies of the Bragg structures is determined via processing a beat signal of the address frequencies on the photodetector, with its parameters making it possible to evaluate the physical fields applied. We formulate and solve a problem of unambiguously determining the central (Bragg) frequency shift of the addressed fiber Bragg structures with unique address frequencies and the same Bragg frequency. These are then combined into a single multi-sensor system with multiplexed response reception on a single photodetector.

550-556

Authors: Pham V.K., Ngo T.P., Gubanova L.A.

This research looks into methods for searching of designs of nonpolarizing interference systems, which provide a small discrepancy between spectral characteristics of the energy reflection/transmission coefficient for s- and p- polarizations. The layer thickness of these systems is a multiple of a quarter wavelength. Depending on the method used, the number of film-forming materials can vary from two to four. Analysis of spectral characteristics shows that in the spectral range of interest the discrepancy between the integral characteristics for s- and p-polarizations is less than 2%.

562-566

Authors: Vasilev D.M., Semin V.V.

In this paper, dynamics of a qubit in an external laser field is investigated for the non-Markov environment described by an Ornstein-Uhlenbeck process. A non-linear non-Markovian stochastic Schrödinger equation is derived for the quantum system. The stochastic equation is preserved for a positive semi-definite of the density matrix and its trace. By the numerical solution of the equation, the probability of finding the system in the excited state and the influence of non-Markov noise parameters on this probability are studie.

577-585

Authors: Podlipnov V.V., Karpeev S.V., Paranin V.D.

A completely symmetrical scheme of a shaper of cylindrical vector beams is proposed in which two diffractive axicons and an interference polarizer placed in-between form a sandwich structure of the smallest possible thickness. The design and experimental study of an interference polarizer for generating the radially polarized radiation at a 1530-nm wavelength is carried out. A pair of amplitude diffractive axicons with a period of 3.62 μm to provide the diffraction angle of 24.5° required for generating radial polarization is fabricated. The transformation of a circularly polarized beam into a radially polarized vortex beam is experimentally demonstrated.

596-604

Authors: Nesterenko D.V., Pavelkin R.A., Hayashi S.

In this work, we consider the use of planar sensing structures, which support excitation of surface plasmon polarition (SPP) modes, for detecting changes in solvents, i.e. water, ethanol, isopropanol. In the structures under study, SPP modes propagate along the interfaces between metals and general solvents. The analysis of characteristics of the resonance response is based on Fano’s approximation within the coupled-mode theory in the visible and infrared regions. The maximum sensitivity and field enhancement are revealed in the near- and mid-infrared regions in the case of ethanol and isopropanol, which enables sensing applications beyond the regions of water absorption.

611-617

Authors: Kurochkin S.V.

A method of topological data analysis is proposed that allows one to find out the homotopy type of the object under study. Unlike mature and widely used methods based on persistent homologies, our method is based on computing differential invariants of some map associated with an approximating map. Differential topology tools and the analogy with the main result in Morse theory are used. The approximating map can be constructed in the usual way using a neural network or otherwise. The method allows one to identify the homotopy type of an object in the plane because the number of circles in the homotopy equivalent object representation as a wedge is expressed through the degree of some map associated with the approximating map. The performance of the algorithm is illustrated by examples from the MNIST database and transforms thereof. Generalizations and open questions relating to a higher-dimension case are discussed.

627-631

Authors: Vaganov S.E.

The architecture of an artificial neural network that solves the problem of constructing interpolation formulas for doubling the size of images is proposed. The trained model receives a 4×4 matrix as an argument. The result is an interpolation formula represented as a weight vector for 4 points. A comparison of the main quality assessments of the proposed method with some well-known adaptive approaches is made. The results of the comparative analysis show that the proposed approach has a better interpolation quality than NEDI and DCCI methods.

647-652

Authors: Chen H., Ye S., Nedzvedz A., Nedzvedz O., Lv H., Ablameyko S.

Road traffic analysis is an important task in many applications and it can be used in video surveillance systems to prevent many undesirable events. In this paper, we propose a new method based on integral optical flow to analyze cars movement in video and detect flow extreme situations in real-world videos. Firstly, integral optical flow is calculated for video sequences based on optical flow, thus random background motion is eliminated; secondly, pixel-level motion maps which describe cars movement from different perspectives are created based on integral optical flow; thirdly, region-level indicators are defined and calculated; finally, threshold segmentation is used to identify different cars movements. We also define and calculate several parameters of moving car flow including direction, speed, density, and intensity without detecting and counting cars. Experimental results show that our method can identify cars directional movement, cars divergence and cars accumulation effectively.

661-670

Authors: Sherendak V.P., Bratchenko I.A., Myakinin O.O., Volkhin P.N., Khristoforova Yu.A.,

In the paper, we present test results of methods for the noninvasive diagnosis of skin neoplasms, based on the hyperspectral registration of images by using a camera with an acousto-optic tunable filter. For the identification of oncological pathologies, an integral spectral index has been proposed for a set of concentric regions around the source of neoplasm growth for the tissue sample under study. As well as taking account of changes in the spectral properties of the tissue, the introduced index indirectly takes into account classical ABCD dermatoscopic features: asymmetry, border irregularity, color diversity, and the tumor diameter. Results of training set separating are presented and the applicability of the proposed approaches to the clinical practice is shown.

677-691

Authors: Sirota A.A., Donskikh A.O., Akimov A.V., Minakov D.A.

A problem of non-parametric multivariate density estimation for machine learning and data augmentation is considered. A new mixed density estimation method based on calculating the convolution of independently obtained kernel density estimates for unknown distributions of informative features and a known (or independently estimated) density for non-informative interference occurring during measurements is proposed. Properties of the mixed density estimates obtained using this method are analyzed. The method is compared with a conventional Parzen-Rosenblatt window method applied directly to the training data. The equivalence of the mixed kernel density estimator and the data augmentation procedure based on the known (or estimated) statistical model of interference is theoretically and experimentally proven. The applicability of the mixed density estimators for training of machine learning algorithms for the classification of biological objects (elements of grain mixtures) based on spectral measurements in the visible and near-infrared regions is evaluated.

337-346

Authors: V.V. Kotlyar, S.S. Stafeev, A.A. Kovalev

Using the Richards-Wolf formalism, we obtain general expressions for all components of the electric and magnetic strength vectors near the sharp focus of an optical vortex with the topological charge m and nth-order azimuthal polarization. From these equations, simple consequences are derived for different values of m and n. If m = n > 1, there is a non-zero intensity on the optical axis, like the one observed when focusing a vortex-free circularly polarized light field. If n = m + 2, there is a reverse flux of light energy near the optical axis in the focal plane. The derived expressions can be used both for simulating the sharp focusing of optical fields with the double singularity (phase and polarization) and for a theoretical analysis of focal distributions of the intensity and the Poynting vector, allowing one to reveal the presence of rotational symmetry or the on-axis reverse energy flux, as well as the focal spot shape (a circle or a doughnut).

356-367

Authors: V.V. Kotlyar, A.A. Kovalev, A.P. Porfirev

Here we study three different types of astigmatic Gaussian beams, whose complex amplitude in the Fresnel diffraction zone is described by the complex argument Hermite polynomial of the order (n, 0). The first type is a circularly symmetric Gaussian optical vortex with and a topological charge n after passing through a cylindrical lens. On propagation, the optical vortex "splits" into nfirst-order optical vortices. Its orbital angular momentum per photon is equal to n. The second type is an elliptical Gaussian optical vortex with a topological charge n after passing through a cylindrical lens. With a special choice of the ellipticity degree (1: 3), such a beam retains its structure upon propagation and the degenerate intensity null on the optical axis does not “split” into n optical vortices.Such a beam has fractional orbital angular momentum not equal to n. The third type is the astigmatic Hermite-Gaussian beam (HG) of order (n, 0), which is generated when a HG beam passes through a cylindrical lens. The cylindrical lens brings the orbital angular momentum into the original HG beam. The orbital angular momentum of such a beam is the sum of the vortex and astigmatic components, and can reach large values (tens and hundreds of thousands per рhoton). Under certain conditions, the zero intensity lines of the HG beam "merge" into an n-fold degenerate intensity null on the optical axis, and the orbital angular momentum of such a beam is equal to n. Using intensity distributions of the astigmatic HG beam in foci of two cylindrical lenses, we calculate the normalized orbital angular momentum which differs only by 7 % from its theoretical orbital angular momentum value (experimental orbital angular momentum is –13,62, theoretical OAM is –14.76).

376-384

Authors: V.S. Vasilyev, A.I. Kapustin, R.V. Skidanov, V.V. Podlipnov,N.A. Ivliev,S.V. Ganchevskaya

We described an experiment on passing Bessel beams through the atmosphere with heat-trolled flows. We showed that at small distances, while passing through the region with a hot air flow, the Bessel beam can be distorted to a complete loss of the structure, but with further propagation over large distances it completely restores its structure. We also described an experiment with the passage of superpositions of vortex beams through the atmosphere with heat flows and aerosols.

391- 396

Authors: M.S. Kuzmin, V.V. Davydov, S.A. Rogov

A mathematical description of a coherent optical correlator for the multi-raster input of long signals is given. It is shown that such an input makes it possible to reduce the value of false correlation maxima that are generally found at the output of a correlator with a single-raster input. It is shown that false maxima do not appear when processing signals with a thumbtack ambiguity function, allowing one to do without a multi-raster input. The results of the theoretical analysis are confirmed by experiments with chirp signals and M-sequence type signals.

402-411

Authors: A.V. Mingalev, A.V. Belov, I.M. Gabdullin, R.R. Agafonova, S.N. Shusharin

The paper presents a comparative analysis of several methods for recognition of test-object position in a thermal image when setting and testing characteristics of thermal image channels in an automated mode. We consider methods of image recognition based on the correlation image comparison, Viola-Jones method, LeNet classificatory convolutional neural network, GoogleNet (Inception v.1) classificatory convolutional neural network, and a deep-learning-based convolutional neural network of Single-Shot Multibox Detector (SSD) VGG16 type. The best performance is reached via using the deep-learning-based convolutional neural network of the VGG16-type. The main advantages of this method include robustness to variations in the test object size; high values of accuracy and recall parameters; and doing without additional methods for RoI (region of interest) localization.

419-433

Authors: A.A. Egorova ,V.A. Fedoseev

The article discusses semi-fragile digital watermarking systems designed to protect JPEG images against unauthorized changes. These systems allow detecting and locating changes, and some of them are able to restore the original content. Formal schemes describing the procedures for watermark embedding and authentication are given. We consider more than a dozen systems of this type and classify them according to various criteria. We also consider the results of experimental studies of these systems estimating their level of distortions arising from watermark embedding. In addition, we test the systems whether they are able to operate in the semi-fragile way.

446-454

Authors: Afef Bettaieb, Nabila Filali, Taoufik Filali, Habib Ben Aissia

Accurate detection of air bubbles boundaries is of crucial importance in determining the performanceand in the study of various gas/liquid two-phase flow systems. The main goal of this work is edge extraction of air bubbles rising in two-phase flow in real-time. To accomplish this, a fast algorithm based on local variance is improved and accelerated on the GPU to detect bubble contour. The proposed method is robust against changes of intensity contrast of edges and capable of giving high detection responses on low contrast edges. This algorithm is performed in two steps: in the first step, the local variance of each pixel is computed based on integral image, and then the resulting contours are thinned to generate the final edge map. We have implemented our algorithm on an NVIDIA GTX 780 GPU. The parallel implementation of our algorithm gives a speedup factor equal to 17x for high resolution images (1024×1024 pixels) compared to the serial implementation. Also, quantitative and qualitative assessments of our algorithm versus the most common edge detection algorithms from the literature were performed. A remarkable performance in terms of results accuracy and computation time is achieved with our algorithm.

464-473

Authors: S.M. Borzov, M.A. Guryanov, O.I. Potaturkin

The article is devoted to the effectiveness research of methods of controlled spectral and spectral-spatial classification of hyperspectral data. In particular, minimum distance, support vector machine, mahalanobis distance and maximum likelihood methods are considered on the example of vegetative cover types differentiation. Significant attention is paid to studying the dependence of the accuracy of data classification with listed methods on the spectral features number and their selection method. The perspectivity of complex processing of spectral and spatial features, considering the correlation of close pixels, is demonstrated. The experimental results obtained with various methods of forming training sets are presented.

484- 491

Authors: V.A. Fursov, Ye.V. Goshin, K.S. Medvedeva

The article is devoted to the problem of improving the quality of images recorded using lowresolution optical instruments, including diffraction-based cameras. A two-stage image correction technology is proposed. At the first stage, the correction is carried out using a linear FIR filter with a centrally symmetric frequency response in the form of quadratic and exponential functions. The resulting image is then processed with a non-linear filter that performs computer retouching of image areas characterized by a noticeable brightness difference. This procedure is only performed on those pixels in which the absolute value of gradients in different directions is sufficiently high, that is, they are located on the borders of areas with different intensity levels. This allows us to avoid noise amplification in the background, which is typical of traditional filters. The examples of the implementation are provided, showing the possibility of achieving high sharpness and illustrating how the filter can be adjusted by visual perception.

504-506

Authors: V.G. Volostnikov

At first sight, any rotation generates some angular momentum (it is true for a solid body). But these characteristics (rotation and orbital angular momentum) are rather different for optics and mechanics. In optics there are the situation when the rotation is important. On the other hand, there are the cases where the nonzero orbital angular momentum is necessary. The main goal of this article is to investigate a relationship between a rotation under propagation of spiral beam and its angular momentum.

159-167

Authors: Kharitonov S.I., Volotovsky S.G., Khonina S.N.

The work is devoted to the study of the caustics of radial beams. Analytical expressions for caustic surfaces of wave fronts created by radially symmetric diffractive optical elements are found. The result is presented in a curvilinear coordinate system consistent with the caustic surface. An asymptotic representation of the Kirchhoff integral near the optical axis is obtained, ensuring the correct calculations in the non-paraxial case.

174-183

Authors: Kotlyar V.V., Nalimov A.G., Stafeev S.S.

Using Jones matrices and vectors, we show that an optical metasurface composed of a set of subwavelength binary diffraction gratings and characterized by an anisotropic transmittance described by a polarization rotation matrix by the angle mφ, where φ is the polar angle, forms an m-th order azimuthally or radially polarized beam when illuminated by linearly polarized light, generating an optical vortex with the topological charge m upon illumination by circularly polarized light. Such a polarization-phase converter (PPC) performs a spin-orbit transformation, similar to that performed by liquid-crystal q-plates. Using a FDTD method, it is numerically shown that when illuminating the PPC by a uniformly (linearly or circularly) polarized field with topological charge m = 2 and then focusing the output beam with a binary zone plate, a reverse on-axis light flow is formed, being comparable in magnitude with the direct optical flow. Moreover, the reverse flows obtained when focusing the circularly polarized optical vortex with the topological charge m = 2 and the second-order polarization vortex are shown to be the same in magnitude.

193-199

Authors: Stafeev S.S., Kotlyar V.V.

In this paper, we have investigated the focusing of a second-order cylindrical vector beam by using a high numerical aperture (NA) lens limited by a ring aperture using the Richards-Wolf formulae. It was shown that the range of negative on-axis projections of the Poynting vector could be increased by increasing the depth of focus through the use of a ring aperture. It was shown that when focusing light with a lens with NA = 0.95, the use of a ring aperture limiting the entrance pupil angle to 0.9 of maximum, allows the depth of the region of negative on-axis Poynting vector projections to be four times increased, with the region width remaining almost unchanged and varying from 0.357 to 0.352 of the incident wavelength. Notably, the magnitude of the reverse energy flow was found to be larger than the direct one by a factor of 2.5.

209-219

Authors: Antonov A.I., Vasin L.A., Greisukh G.I.

Coefficients required for the algorithmization and implementation of the rigorous coupled-waves analysis are derived for a Fourier series expansion of the permittivity of a linear-sawtooth relief with positive tangent of the working surface angle and vertical backward slope. Approaches to the implementation of the rigorous coupled-waves analysis are described and compared in terms of stability and efficiency, namely, the approach of a purposeful transformation of the transmission matrix and the approach of Gaussian illuminations. It was concluded that the most appropriate approach for determining the diffraction efficiency for cases of deep diffraction structures is the approach of purposeful transformation of the transmission matrix.

231-237

Authors: Shabanov A.V., Korshunov M.A., Bukhanov E.R.

Calculations were performed using the transfer matrix of one-dimensional photonic crystals with low contrast and asymmetric structures of different periods. Such structures have been found in many plants. When joining two successively connected sublattices with different periods, an increase is observed in the amplitude of the electromagnetic field and the density of photon states inside the structure, and their change depends on the asymmetry of the thickness of the sublattices.

245-250

Authors: Asatryan D.G.

This paper is devoted to application of gradients field characteristics in selected problems of image intellectual analysis and processing. To analyse the properties and structure of an image several approaches and models based on the use of the gradients field characteristics, are proposed. In this paper, models based on Weibull distribution are considered, an image dominant direction estimation algorithm using the parameters of scattering ellipse of gradients field components is proposed, and a similarity measure of two images with arbitrary dimensions and orientation is proposed. Some examples of applications of these models for estimation of blur and structuredness of an image, for the quality assessment of resizing and rotating algorithms, as well as for detection of a specified object on the image delivered by an unmanned aerial vehicle, are given.

258-263

Authors: Ga H., Zeng W.

With the rapid development of network technology, more and more digital images are transmitted on the network, and gradually become one important means for people to access the information. The security problem of the image information data increasingly highlights and has become one problem to be attended. The current image encryption algorithm basically focuses on the simple encryption in the frequency domain or airspace domain, and related methods also have some shortcomings. Based on the characteristics of wavelet transform, this paper puts forward the image compression and encryption based on the wavelet transform and chaos by combining the advantages of chaotic mapping. This method introduces the chaos and wavelet transform into the digital image encryption algorithm, and transforms the image from the spatial domain to the frequency domain of wavelet transform, and adds the hybrid noise to the high frequency part of the wavelet transform, thus achieving the purpose of the image degradation and improving the encryption security by combining the encryption approaches in the spatial domain and frequency domain based on the chaotic sequence and the excellent characteristics of wavelet transform. Testing experiments show that such algorithm reduces the memory consumption and implements the complexity, not only can decrease the key spending and compress the time spending, but also can improve the quality of decoded and reconstructed image, thus showing good encryption features with better encryption effect.

270-276

Authors: Rajalakshmi C., Germanus Al.M., Balasubramanian R.

The most important barrier in the image forensic is to ensue a forgery detection method such can detect the copied region which sustains rotation, scaling reflection, compressing or all. Traditional SIFT method is not good enough to yield good result. Matching accuracy is not good. In order to improve the accuracy in copy move forgery detection, this paper suggests a forgery detection method especially for copy move attack using Key Point Localized Super Pixel (KLSP). The proposed approach harmonizes both Super Pixel Segmentation using Lazy Random Walk (LRW) and Scale Invariant Feature Transform (SIFT) based key point extraction. The experimental result indicates the proposed KLSP approach achieves better performance than the previous well known approaches.

282-295

Authors: Lebedev L.I., Yasakov Yu.V., Utesheva T.H., Gromov V.P., Borusjak A.V., Turlapov V.E.

We study a problem of complex analysis and monitoring of the environment based on Earth Sensing Data, with the emphasis on the use of hyperspectral images (HSI), and propose a solution based on developing algorithmic procedures for HSI processing and storage. HSI is considered as a two-dimensional field of pixel signatures. Methods are proposed for evaluating the similarity of a HSI pixel signature with a reference signature, via simple alignment transformations: identical; amplitude scaling; shift along y-axis; and a combination of the last two. A clustering / recognition method with self-learning is proposed, which determines values of the transformation parameters that ensure the alignment of the current pixel signature with the reference signature. Similarity with the reference is determined by a standard deviation value. A HSI compression method with controlled losses has been proposed. The method forms a basis via accumulating reference signatures and represents the rest of the signatures by parameters matching them with the already detected class-reference signature. In an experiment with the GSI f100520t01p00-12 data of the AVIRIS spectrometer, the method provided a 2 % loss and compression coefficients of the original HSI ranging from 43 to 165 for various types of alignment transformation, while not requiring archiving and thus maintaining active access to the HSI and using the list of references as an analogue of the HSI palette. An algorithm for the formation of dense groups of detectable objects (for example, oil spots) and their nonconvex contouring, controlled by 4 parameters, is proposed. A pilot version of the concept of geographic information system (GIS) and an appropriate database management system (DBMS) was built and implemented, which provides monitoring and is based on the prioritized processing and storage of the HSI, which serve as a data source for the system. A laboratory complex with new algorithms for processing and storing the GSE is introduced into the structure of the system.

304-315

Authors: Ilyasova N.Yu., Shirokanev A.S., Kupriyanov A.V., Paringer R.A.

The paper proposes a technology for effective feature selection to localize individual characteristics of anatomical and pathological structures in the human eye fundus. Such an approach allows the intellectual analysis of features to be conducted using color subspaces and the regions of interest to be identified. This problem is relevant because in this way the efficiency of laser coagulation surgery can be improved. The technology is based on the texture analysis of certain image patterns. The initial textural attributes are derived from different statistical image descriptors calculated using the MaZda library (image histogram, image gradient, series length and adjacency matrices). The analysis of the feature space informativity and selection of the most effective features are carried out using the discriminant data analysis. The best-size image fragmentation windows for eye fundus clustering and sets of features that provide the necessary accuracy in identifying the regions of interest were derived via analyzing the following four image classes: exudates, thick vessels, thin vessels, and healthy areas. The feature selection technology was based on clustering using a K-means method, with the Euclidean and Mahalanobis distance used as a similarity measure. The required minimum size of the fragmentation window and the similarity measure were chosen from a criterion of the minimum clustering error among all the smallest window sizes. The article also presents a system for automatically forming a coagulate plan, expected to be used to support the decision-making during laser retinal coagulation surgery in the treatment of diabetic macular edema. This system is currently being developed based on the proposed technology.

324-331

Authors: Kirsh D.V., Shirokanev A.S., Kupriyanov A.V.

The article deals with a problem of three-dimensional crystal lattice reconstruction, which is an important stage in the X-ray structural analysis. The accuracy of parametric and structural identification of crystals directly depends on the quality of crystal lattice reconstruction. The proposed algorithm of reconstruction of a three-dimensional crystal lattice is based on minimizing the distances from each node to a line projected onto a specified plane. Three sets of two-dimensional node coordinates, obtained from three two-dimensional projections, are used as input data. We performed an analytical calculation of the reconstruction error, allowing the total reconstruction accuracy to be estimated. The results of computational experiments confirmed the high quality of the proposed reconstruction algorithms and its stability against the distortion of node coordinates. In addition, we revealed a problem of lattice system separability, with the identification accuracy for monoclinic, rhombic and tetragonal systems found to be 34%, 53% and 10%, respectively.

5-13

Authors: Baulin F.B., Buryi E.V.

In this article we described common problems encountered by various researchers when synthesizing recognition systems based on laser range profile, developed for non-cooperative vehicle recognition. Proven approaches to tackling the problems are also considered. The contemporary level of the technology and guidelines for developing the recognition systems are discussed. Based on the research results combined, it is concluded that such systems are not only feasible, but also in demand.

25-34

Authors: Barshak E.V., Yavorsky M.A., Vikulin D.V., Lapin B.P., Volyar A.V., Alexeyev C.N.

In this paper we investigated a problem of intermode dispersion within a group of optical vortices with an azimuthal number greater than or equal to 1 in circular optical fibers. It was established that, while there is no dispersion between optical vortices with topological charge ± 1, both standard polarization mode dispersion and a new-form topological mode dispersion occurred between optical vortices with the topological charge greater than 1. The dependence of the dispersion of optical vortices on the wavelength for the gradient and step-index fibers with variable parameters was numerically obtained and analyzed. A feasibility of zero mode dispersion in step-index fibers was established.

42-53

Authors: Kotlyar V.V., Kovalev A.A., Porfirev A.P.

We propose and study numerically and experimentally two methods for determining the orbital angular momentum (OAM) of paraxial laser beams. One method is based on registering the intensity in the Fresnel zone, numerically averaging this intensity over the polar angle at discrete radii, and solving a system of linear equations to find squared modules of the coefficients of the light field expansion in terms of basis functions. The other method is based on registering two intensity distributions in the Fourier plane of two cylindrical lenses rotated 90 degrees relative to each other, and calculating the first-order moments of the measured intensities. The experimental error of the OAM determination is about 1% for small fractional OAM (up to 4), and about 8% for large fractional OAM (up to 30).

63-71

Authors: Gorbatsevich V.S., Moiseenko A.S., Vizilter Y.V.

Face detection is one of the most popular computer vision tasks. There are a lot of face detection approaches proposed including different CNN-based techniques, but the problem of optimal balancing between detection quality and computational speed is still relevant. In this paper we propose new CNN-based solution for face detection called FaceDetectNet. Our CNN architecture is based on ideas of YOLO/DetectNet and GoogleNet architecture supported with some new tools and implementation details created especially for our face detection application. We propose: original iterative proposal clustering (IPC) algorithm for aggregation of output face proposals formed by CNN and the 2-level “weak pyramid” providing better detection quality on the testing sets containing both small and huge images. Our face detection approach is close to previously proposed SSD-based face detection, but the principal difference is that we use the deep features of top hidden CNN layer for forming the face proposals of any size. Thus we utilize the global semantic and context information for improving the detection quality for small faces. Our FaceDetectNet is trained and tested on the most challenging WIDER FACE detection benchmark. Our algorithm achieves the average precision (AP) 0.69 on the WIDER FACE hard level, and thus outperforms all competitive detectors on the Hard level besides the HR state-of-the-art solution. Note that HR solution is based on essentially deeper and slower CNN, while our FaceDetectNet can work in real-time on the NVIDIA GeForce 1080 GPU. On the other hand, SSD-based face detector with comparable CNN parameters provides AP 0.625 only on the WIDER FACE hard level. So, our approach provides the best quality with reasonable computational speed.

78-82

Authors: Gao H., Zeng W., Chen J.

Image enhancement is a very important process of image preprocessing and it plays a critical role in the improvement of image quality and the follow-up image analysis, which makes the research of image enhancement algorithm a hot research field. Image enhancement not only needs to strengthen image determination and recognition, but also needs to avoid the consequential color distortion. Pseudo-color enhancement is the technique to map different gray scales of a black-and-white image into a color image. As humans have extremely strong ability in distinguishing different colors visually and relatively weak capacity in discriminating gray scales, so, color the gray-scale changes which cannot be differentiated by human eyes so that they can tell them apart. The mapping function in conventional gray-scale transform method is not working well in dark and low-contrast images. So, this paper comes up with an improved gray-scale transformation algorithm. This algorithm can achieve the enhancement, preserve the image colors, process dark and low-contrast images, reinforce the enhancement and improve the blocking effect. The experiment proves that the enhanced image obtained by the method of this paper can have improved average brightness, natural colors and more detail information and it has good application value.

90-98

Authors: Choudhary K., Boori M.S., Kupriyanov A.V.

Monitoring of land use/cover (LULC) change is very important for sustainable development planning study. This research work is to understand natural and environmental situation and its cause such as intensity, distribution and socio and economic effects in Moscow, Russia based on remote sensing and Geographical Information System techniques. A model was developed by following thematic layers: land use/cover, vegetation, soil, geomorphology and geology in ArcGIS 10.2 software using multi-spectral satellite data obtained from Landsat 7 and 8 for the years of 1995, 2005 and 2016 respectively. Increasing scientific and political interest in regional aspects of global environmental changes, there is a strong stimulus to better understand the patterns causes and environmental consequences of LULC expansion in the elevation of Moscow state, one of the areas in the nation with fast economic growth and high population density. A 70 to 300 m inundation land loss scenarios for surface water and sea level rise (SLR) were developed using digital elevation models of study site topography through remote sensing and GIS techniques by ASTER GDEM and Landsat OLI data. The most severely impacted sectors are expected to be the vegetation, wetland and the natural ecosystem. Improved understanding of the extent and response of SLR will help in preparing for adaptation.

105-114

Authors: Stepanov D.N.

In this paper, we develop and research mathematical models that describe image acquisition from two-mirror catadioptric systems, which allow one to generate stereo images using a single camera and two flat mirrors. The main difference between the proposed models and existing solutions in this area is that real camera distortion is introduced into the images. An overview of the main methods of creating 3D models using optical technologies is presented, as well as an overview of types of catadioptric systems depending on the number of mirrors and their shape (curved or flat). The methodology of the research consists in the mathematical modeling of a two-mirror catadioptric system, as well as in a computer experiment using real images that were obtained using a stereo nozzle with two flat mirrors and synthetic images which were generated based on the ray tracing algorithm. Results of the experiments on the camera calibration with a stereo nozzle, as well as results of image rectification using the calibration data and developed mathematical models are presented. The results of the experiments allow us to verify the adequacy of the developed models. The proposed models expand the theory of computer vision and can be used in the creation and research of computer vision systems for robotic complexes.

123-131

Authors: Xue X., Xiang F., Wang H.

Remote sensing image fusion is very important for playing the advantages of a variety of remote sensing data. However, remote sensing image fusion is large in computing capacity and time consuming. In this paper, in order to fuse remote sensing images accurately and quickly, a parallel fusion algorithm of remote sensing image based on NSCT (nonsubsampled contourlet transform) is proposed. In the method, two important kinds of remote sensing image, multispectral image and panchromatic image are used, and the advantages of parallel computing in high performance computing and the advantages of NSCT in information processing are combined. In the method, based on parallel computing, some processes with large amount of calculation including IHS (Intensity, Hue, Saturation) transform, NSCT, inverse NSCT, inverse IHS transform, etc., are done. To realize the method, multispectral image is processed with IHS transform, and the three components, I, H, and S are gotten. The component I and the panchromatic image are decomposed with NSCT. The obtained low frequency components of NSCT are fused with the fusion rule based on the neighborhood energy feature matching, and the obtained high frequency components are fused with the fusion rule based on the subregion variance. Then the low frequency components and the high frequency components after fusion are processed with the inverse NSCT, and the fused component is gotten. Finally, the fused component, the component H and the component S are processed with the inverse IHS transform, and the fusion image is obtained. The experiment results show that the proposed method can get better fusion results and faster computing speed for multispectral image and panchromatic image.

137-154

Authors: Evsutin O.O., Kokurina A.S., Meshcheryakov R.V.

Transmission, processing and storage of information in the infrastructure of the Internet of Things are related to the necessity for solving a number of problems in information security. The main difficulty lies in the fact that the infrastructure of the Internet of Things is not homogeneous and contains many different devices, including those with limited computing resources. One of the approaches to solving these problems is to embed additional information into the transmitted and stored digital objects. In this paper we present a review of methods of embedding information in digital data to provide security in the Internet of Things, including methods of steganographic embedding of information and methods for embedding digital watermarks. We reviewed methods of embedding information into digital images, as well as wireless sensor network data, proposed for use in the Internet of Things. In this paper we defined the advantages and disadvantages of individual methods and groups of methods, also we analyzed their applicability for data protection in the Internet of Things. Relevant trends in this field of research have been identified.