Статьи журнала - Компьютерная оптика

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"Бездифракционные пучки" и их каустики

"Бездифракционные пучки" и их каустики

Пальчикова И.Г.

Статья научная

В настоящей работе обсуждается возможность формирования фокальных областей в различных зонах дифракции и доказывается, что термин "бездифракционные пучки" применяется для обозначения ограниченной в пространстве части тороидальной световой волны. Световая линия, или осевая каустика, является результатом интерференции пересекающихся областей этой волны. Показано, что "бездифракционные пучки" формируются такими оптическими элементами, фазовая функция пропускания которых содержит линейные по радиальной координате слагаемые. Выполнено сравнение оптических характеристик каустик в ближней и в дальней зонах дифракции. Сообщается о синтезе нового дифракционного модулированного аксикона, который формирует две фокальных области различного типа. Приводятся результаты экспериментального исследования его оптических характеристик.

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"Винтовой" пространственный фазовый фильтр

"Винтовой" пространственный фазовый фильтр

Котляр В.В., Сойфер В.А.

Статья научная

Предложено использовать для фокусировки в кольцо фазовый элемент с пропусканием, фаза которого состоит из двух слагаемых: линейно-радиального слагаемого (аксикона) и линейно-азимутального ("винтового") слагаемого. Получены выражения для максимальной интенсивности света на кольце. Также получены выражения для распределения интенсивности света в зонах дифракции Френеля и Фраунгофера для случая дифракции плоской монохроматической волны на "винтовом" фазовом фильтре.

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"Экзотические" бинарные системы счисления для колец целых чисел Гаусса и Эйзенштейна

"Экзотические" бинарные системы счисления для колец целых чисел Гаусса и Эйзенштейна

Чернов Владимир Михайлович

Статья научная

В работе рассматриваются нестандартные бинарные системы счисления для колец целых чисел Гаусса и Эйзенштейна. Принципиальным отличием («экзотичностью») таких систем счисления от канонических систем счисления И. Катаи для квадратичных полей является использование в качестве бинарного «цифрового алфавита» двухэлементного множества, не содержащего числового нуля. В работе синтезируются также алгоритмы представления чисел в рассматриваемой системе счисления и характеризуются возможности эффективной реализации арифметических операций.

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20 лет научному изданию «Компьютерная оптика»

20 лет научному изданию «Компьютерная оптика»

Казанский Н.Л.

Статья

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3D-reconstruction of the human brain

3D-reconstruction of the human brain

Thaller R., Dimitrov L., Wenger E.

Статья научная

It is well known that the peculiar manifestations of talent are related to the morphology of human brain. The systematic researched in this field require a visualization of the individual human brain with high accuracy. This method makes it possible to accomplish a reconstruction of human brain from the series of images obtained with the use of equipment of nuclear magnetic resonance. The research of brain morphology is the basis for further visualisation of human activity through the superimposing measurements obtained by means of EEG.

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3D-визуализация многократно рассеивающих сред

3D-визуализация многократно рассеивающих сред

Захаров В.П., Синдяева А.Р.

Статья научная

Настоящая работа посвящена теоретическим исследованиям распространения низкоинтенсивного лазерного излучения оптического диапазона в многократно рассеивающих средах и направлена на создание универсальной оптической схемы их визуализации. При анализе внутренней структуры объекта и протекающих в нем процессов в большинстве случае необходимо учитывать не абсолютные значения оптических параметров, а их пространственно-временные флуктуации. В связи с этим в качестве базового метода исследования выбран дифференциальный алгоритм метода обратного рассеяния. Построена 3D-модель многократного рассеяния в программной среде TracePro с применением статистического метода Монте-Карло. Проведены численные эксперименты по математическому моделированию взаимодействия лазерного излучения с объектом и визуализации его строения. Определены зависимости дифференциальных характеристик рассеянного излучения от топологии и оптических параметров среды. На основании полученных данных сделан вывод о возможности применения созданной объемной модели для решения задач диагностики многократно рассеивающих объектов, в частности, биообъектов.

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A compact design of a balanced 1x4 optical power splitter based on silicon on insulator slot waveguides

A compact design of a balanced 1x4 optical power splitter based on silicon on insulator slot waveguides

Butt Muhammad Ali, Naresh Kumar Reddy Andra, Khonina Svetlana Nikolaevna

Статья научная

In this paper, a compact design of a balanced 1×4 optical power splitter based on coupled mode theory (CMT) is presented. The design consists of seven vertically slotted waveguides based on the silicon-on-insulator platform. The 1×4 OPS is modelled using commercial finite element method (FEM) simulation tool COMSOL Multiphysics 5.1. The optimized OPS is capable of working across the whole C-band with maximum ~39 % of power decay in the wavelength range 1530 - 1565 nm.

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A framework of reading timestamps for surveillance video

A framework of reading timestamps for surveillance video

Cheng Jun, Dai Wei

Статья научная

This paper presents a framework to automatically read timestamps for surveillance video. Reading timestamps from surveillance video is difficult due to the challenges such as color variety, font diversity, noise, and low resolution. The proposed algorithm overcomes these challenges by using the deep learning framework. The framework has included: training of both timestamp localization and recognition in a single end-to-end pass, the structure of the recognition CNN and the geometry of its input layer that preserves the aspect of the timestamps and adapts its resolution to the data. The proposed method achieves state-of-the-art accuracy in the end-to-end timestamps recognition on our datasets, whilst being an order of magnitude faster than competing methods. The framework can be improved the market competitiveness of panoramic video surveillance products.

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A novel approach for partial shape matching and similarity based on data envelopment analysis

A novel approach for partial shape matching and similarity based on data envelopment analysis

Arhid Khadija, Zakani Fatima Rafii, Sirbal Basma, Bouksim Mohcine, Aboulfatah Mohamed, Gadi Taoufiq

Статья научная

Due to the growing number of 3D objects in digital libraries, the task of searching and browsing models in an extensive 3D database has been the focus of considerable research in the area. In the last decade, several approaches to retrieve 3D models based on shape similarity have been proposed. The majority of the existing methods addresses the problem of similarity between objects as a global matching problem. Consequently, most of these techniques do not support a part of the object as a query, in addition to their poor performance for classes with globally non-similar shape models and also for articulated objects. The partial matching technique seems to be a suitable solution to these problems. In this paper, we address the problem of shape matching and retrieval. We propose a new approach based on partial matching in which each 3D object is segmented into its constituent parts, and shape descriptors are computed from these elements to compare similarities. Several experiments investigated that our technique enables fast computing for content-based 3D shape retrieval and significantly improves the results of our method based on Data Envelopment Analysis descriptor for global matching.

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A parallel fusion method of remote sensing image based on NSCT

A parallel fusion method of remote sensing image based on NSCT

Xue Xiaorong, Xiang Fang, Wang Hongfu

Статья научная

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...

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A remote sensing and GIS based approach for land use/cover, inundation and vulnerability analysis in Moscow, Russia

A remote sensing and GIS based approach for land use/cover, inundation and vulnerability analysis in Moscow, Russia

Choudhary Komal, Boori Mukesh Singh, Kupriyanov Alexander Victorovich

Статья научная

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.

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A solution method for image distortion correction model based on bilinear interpolation

A solution method for image distortion correction model based on bilinear interpolation

Li Jun, Su Jie, Zeng Xiliang

Статья научная

In the process of the image generation, because the imaging system itself has differences in terms of nonlinear or cameraman perspective, the generated image will face the geometric distortion. Image distortion in general is also a kind of image degradation, which needs the geometric transform to correct each pixel position of the distorted images, so as to regain the original spatial relationships between pixels and the original grey value relation, and which is also one of important steps of image processing. From the point of view of the digital image processing, the distortion correction is actually a process of image restoration for a degraded image. In image processing, in terms of the image quality improvement and correction technology, namely the image restoration, with the wide expansion of digital image distortion correction processing applied, the processing technology of the image restoration has also become a research hotspot. In view of the image distortion issue, this paper puts forward the image distortion correction algorithm based on two-step and one-dimensional linear gray level interpolation to reduce the computation complexity of the bilinear interpolation method, and divide the distorted image into multiple quadrilaterals, and the area of the quadrilateral is associated with the distortion degree of the image in the given region, and express the region distortion of each quadrilateral with the bilinear model, thus determining parameters of bilinear model according to the position of the quadrilateral vertex in the target image and the distorted image...

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Ab initio modeling of Raman and infrared spectra of calcite

Ab initio modeling of Raman and infrared spectra of calcite

Saleev Vladimir Anatolievich, Kalinin Nikita Victorovich

Статья научная

Calcite is the most thermodynamically stable polymorphic phase of the CaCO3 crystal. It is widely used in modern optical instruments operating in the infrared and visible wavelengths of electromagnetic radiation. In particular, due to its anisotropic properties, calcite is used in polarization optics devices. Ab initio quantum mechanical modeling of the Raman and infrared spectra of calcite makes it possible to better understand the structure and nature of the chemical bonds of the compound, and find the optimal conditions for the effective use of unique properties of calcite in photonics tools. The calculations are performed within the framework of the density functional theory in the CRYSTAL program, using the “hybrid” B3LYP functional and the all-electronic bases of the STO-6G, PO-TZVP and BSD atomic orbitals of the Gaussian type. The obtained results for the elastic constants, Raman and infrared spectra of calcite agree satisfactorily with the available experimental data for the basic sets of POB-TZVP and BSD.

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Abstracts

Abstracts

Тезисы

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Aerial vehicles detection and recognition for UAV vision system

Aerial vehicles detection and recognition for UAV vision system

Muraviev Vadim Sergeevich, Smirnov Sergey Aleksandrovich, Strotov Valery Viktorovich

Статья научная

This article focuses on aerial vehicle detection and recognition by a wide field of view monocular vision system that can be installed on UAVs (unmanned aerial vehicles). The objects are mostly observed on the background of clouds under regular daylight conditions. The main idea is to create a multi-step approach based on a preliminary detection, regions of interest (ROI) selection, contour segmentation, object matching and localization. The described algorithm is able to detect small targets, but unlike many other approaches is designed to work with large-scale objects as well. The suggested algorithm is also intended to recognize and track the aerial vehicles of specific kind using a set of reference objects defined by their 3D models. For that purpose a computationally efficient contour descriptor for the models and the test objects is calculated. An experimental research on real video sequences is performed. The video database contains different types of aerial vehicles: airplanes, helicopters, and UAVs. The proposed approach shows good accuracy in all case studies and can be implemented in onboard vision systems.

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Algorithm for calculation of the power density distribution of the laser beam to create a desired thermal effect on technological objects

Algorithm for calculation of the power density distribution of the laser beam to create a desired thermal effect on technological objects

Murzin Serguei Petrovich, Bielak Robert, Liedl Gerhard

Статья научная

Based on the use of methods for solving the inverse problem of heat conduction, we developed an algorithm for calculating the power density distribution of the laser beam to create a desired thermal effect on technological objects. It was shown that the redistribution of power density of moving distributed surface heat sources can adjust the temperature distribution in the treated zone. The results of thermal processes calculation show the ability of the developed algorithm to create a more uniform temperature field across the width of the heat affected zone. Equalization of maximum temperature values is achieved in the center and on the periphery of the heat affected zone with an increase in the width of the regions, where required temperature is reached. The application of diffractive optical elements gives an opportunity to obtain the required properties of treated materials in the heat affected zone. The research performed has enabled parameters of the temperature field in chrome-nickel-molybdenum steel to be adjusted for laser heat treatment. In addition to achieving uniform temperature conditions across the width of the heat affected zone, the proposed approach allows the increase of the width of the isotherms of the temperature fields; this provides an opportunity to process a larger area per unit time at the same laser beam power.

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An adaptive image in painting method based on the modified Mumford-Shah model and multiscale parameter estimation

An adaptive image in painting method based on the modified Mumford-Shah model and multiscale parameter estimation

Thanh Dang Ngoc Hoang, Surya Prasath V. B., Son Nguyen Van, Hieu Le Minh

Статья научная

Image inpainting is a process of filling missing and damaged parts of image. By using the Mumford-Shah image model, the image inpainting can be formulated as a constrained optimization problem. The Mumford-Shah model is a famous and effective model to solve the image inpainting problem. In this paper, we propose an adaptive image inpainting method based on multiscale parameter estimation for the modified Mumford-Shah model. In the experiments, we will handle the comparison with other similar inpainting methods to prove that the combination of classic model such the modified Mumford-Shah model and the multiscale parameter estimation is an effective method to solve the inpainting problem.

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An efficient block-based algorithm for hair removal in dermoscopic images

An efficient block-based algorithm for hair removal in dermoscopic images

Zaqout Ihab Salah

Статья научная

Hair occlusion in dermoscopy images affects the diagnostic operation of the skin lesion. Segmentation and classification of skin lesions are two major steps of the diagnostic operation required by dermatologists. We propose a new algorithm for hair removal in dermoscopy images that includes two main stages: hair detection and inpainting. In hair detection, a morphological bottom-hat operation is implemented on Y-channel image of YIQ color space followed by a binarization operation. In inpainting, the repaired Y-channel is partitioned into 256 non-overlapped blocks and for each block, white pixels are replaced by locating the highest peak, using a histogram function and a morphological close operation. The proposed algorithm reports a true positive rate (sensitivity) of 97.36 %, a false positive rate (fall-out) of 4.25 %, and a true negative rate (specificity) of 95.75 %. The diagnostic accuracy achieved is recorded at a high level of 95.78 %.

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An improved gray-scale transformation method for pseudo-color image enhancement

An improved gray-scale transformation method for pseudo-color image enhancement

Gao Haibo, Zeng Wenjuan, Chen Jifeng

Статья научная

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.

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