Computer Optics

682-691

Authors: S.V. Karpeev, V.V. Podlipnov, S.A. Degtyarev, A.M. Algubili

Complex polarization-phase transformations are considered, which are implemented using easy-to-manufacture optical elements. The manufacturing technology of such elements is based on the axially symmetric discretization of the required polarization and phase distributions. This representation leads to optical elements in the form of sector sandwich structures consisting of polarizing and phase plates stacked together. The paper numerically and experimentally investigates the main types of such sector sandwich structures for the formation of second-order cylindrical polarizations.

701-712

Authors: C.N. Alexeyev, S.S. Aliyeva, E.V. Barshak, B.P. Lapin, M.A. Yavorsrky

In this paper, we studied transformations of structured light and its angular momentum in a three-coil optical snake – a coil resonator composed of 3 evanescently uniformly coupled coils of a multimode fiber. We have suggested a fully vectorial theory of normal modes of the 3-coil resona-tor, which takes account of the spin-orbit interaction. On the basis of the analytical expressions for such normal modes and their propagation constants we have studied transmission of some types of structured light beams – optical vortices, Hermite-Gaussian-like and Laguerre-Gaussian beams – through such a system. We have shown the possibility of a super-efficient parametric control over the topological charge, orbital and spin angular momenta of the outcoming optical field by this system. We have theoretically demonstrated implementation of logic X and Y Pauli gates for light beams carrying orbital angular momentum on the basis of such a 3-coil resonator.

724-732

Authors: A.O. Frolov, А.V. Ustinov, S.N. Khonina

In this paper, we study a change in the propagation trajectory of a set of autofocusing laser beams using a fractional Fourier transform. Clusters of displaced bounded Airy-Gaussian beams supplemented by a phase function that deflects the beam similarly to a prism are considered. The shift and phase deviation (according to the carrier spatial frequencies) make it possible to change the propagation trajectory of a set of autofocusing beams. The influence of the parameters under consideration on the properties of autofocusing of a cluster of Airy-Gaussian beams is investigated by means of numerical simulation.

741-751

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

The work is devoted to the development of the quantum theory of diffractive optical elements. Aspects of quantum optics are considered by the example of light diffraction from a dielectric plate in a resonator. The paper shows the connection between the classical and quantum solution of the problem of diffraction by a dielectric plate. Expressions are obtained for the eigenmodes of such a resonator, as well as for the operators of the vector magnetic potential and the electric field strength. The method proposed in this paper can be easily extended to dielectric plates with a diffractive microrelief, that is, to diffractive optical elements.

763-773

Authors: N.N. Vasilyuk

A method for calculating of a blur kernel arising from the rotation of a digital camera is proposed. The rotation is measured with a three-axis gyroscope attached to the camera. Differential equations of a continuous trajectory of the rotational blur starting from a selected pixel are obtained. These equations are presented both in the form of an explicit system of differential equations for the blur curve in the focal plane and in the form of a matrix equation for the increment of the camera attitude. An expression is given for the integral of the energy illumination from a point light source along the continuous blur trajectory. The integral takes into account the point spread function and the aperture functions of individual photosensitive cells of the photodetector array. The calculation of the integral values for all photosensitive cells illuminated with the point source gives a discrete kernel of rotational blur starting at the selected pixel. Algorithms for the numerical integration of the blur equations are described. The analysis of the blur equations are carried out, characteristic features of the kernels are highlighted and their non-homogeneity is shown, with the kernels of rotational blur revealed not to coincide with each other for different pixels. An example of the synthesis of the blur kernels for given rotation parameters of the digital camera is given.

783-789

Authors: S.H. Jeevith, S. Lakshmikanth

In various computer vision applications, the moving object detection is an essential step. Principal Component Analysis (PCA) techniques are often used for this purpose. However, the performance of this method is degraded by camera shake, hidden moving objects, dynamic background scenes, and / or fluctuating exposure. Robust Principal Component Analysis (RPCA) is a useful approach for reducing stationary background noise as it can recover low rank matrices. That is, moving object is formed by the low power models and the static background of RPCA. This paper proposes a simple alternative minimization algorithm to fix minor discrepancies in the original Principal Component Pursuit (PCP) or RPCA function. A novel hybrid method of cartoon texture features used as a data matrix for RPCA taking into account low-ranking and rare matrix is presented. A new non-convex function is proposed to better control the low-range properties of the video background. Simulation results demonstrate that the proposed algorithm is capable of giving consistent random estimates and can indeed improve the accuracy of object recognition in comparison with existing methods.

801-807

Authors: A.D. Sokolova, A.V. Savchenko, S.I. Nikolenko

One of main issues in face identification is the lack of training data of specific type (bad quality image, varying scale or illumination, children/old people faces, etc.). As a result, the recogni-tion accuracy may be low for input images which are not similar to the majority of images in the dataset used to train the feature extractor. In this paper, we propose that this issue is dealt with by the automatic detection of such out-of-distribution data based on the addition of a preliminary stage of their automatic rejection using a special convolutional network trained using a set of rare data collected using various transformations. To increase the computational efficiency, the decision about the presence of a rare image is made on the basis of the same face descriptor that is used in the classifier. Experimental research confirmed the accuracy improvement of the proposed approach for several datasets of faces and modern neural network descriptors.

818-827

Authors: D.E. Plotnikov, P.A. Kolbudaev, E.A. Loupian

The paper describes a method for automatic subpixel-accurate geographic referencing of imagery acquired by KMSS-M with 60 m spatial resolution, based on leveraging a coarse, reconstructed, cloud-free and daily updated MODIS surface reflectance reference image. The method is based on maximizing Pearson's correlation value when determining an optimal local displacement of the distorted image fragment by comparing with the reference image. To assess the effectiveness of the method when used over continental-scale and heterogeneous areas, three experiments were carried out providing quantitative estimates of imagery registration errors: an experiment with model datasets, an experiment to estimate the absolute registration error of MODIS reference imagery, and an experiment to estimate the registration error of geocorrected KMSS-M data. Experimental evaluation of the method based on model datasets of decameter-resolution Sentinel-2 (MSI) imagery demonstrated its robustness when used over a variety of environmental conditions over a one year-long observation period. The average georeferencing error of MODIS coarse-resolution reference was shown to be less than 20 meters in Red and Near-infrared bands. Corrected KMSS-M imagery evaluation over the Russian Grain Belt within 2020 has shown, on average, the subpixel referencing accuracy both in Red and Near-infrared bands, while the average absolute georeferencing error of the original uncorrected KMSS-M imagery was shown to be about 3 kilometers. Subpixel registration accuracy of KMSS-M imagery, corrected with MODIS-based coarse-resolution reference, opens new prospects for using multi-temporal analysis of this multispectral surface reflectance data in a variety of scientific and practical applications associated with vegetation cover satellite monitoring. The technological flexibility of the method ensures its applicability to data from other satellite systems for Earth optical remote sensing.

840-847

Authors: Е.E. Aydarkin, N.S. Mogilevskaya

The paper investigates the ability of the equal-weight columns method to resist grouping erasures. The Gilbert model for error generation flow is adapted for the case of erasures. A simulation model of the erasure-correction channel is constructed with the possibility of choosing the type of erasure and the method of protection against erasure. With the help of this model, an experimental study of the equal-weight column method and its modifications is conducted and a detailed analysis of the results with conclusions for developers of networks and data transmission channels is carried out. An estimate of the decoding probability is constructed. A method of dealing with clustering erasures by using additional redundancy is proposed.