Image Formation Method Research Articles

Resolving full-wave through-wall transmission effects in multi-static synthetic aperture radar

Through-wall synthetic aperture radar (SAR) imaging is of significant interest for security purposes, in particular when using multi-static SAR systems consisting of multiple distributed radar transmitters and receivers to improve resolution and the ability to recognise objects. Yet there is a significant challenge in forming focused, useful images due to multiple scattering effects through walls, whereas standard SAR imaging has an inherent single scattering assumption. This may be exacerbated with multi-static collections, since different scattering events will be observed from each angle and the data may not coherently combine well in a naive manner. To overcome this, we propose an image formation method which resolves full-wave effects through an approximately known wall or other arbitrary obstacle, which itself has some unknown ‘nuisance’ parameters that are determined as part of the reconstruction to provide well focused images. The method is more flexible and realistic than existing methods which treat a single wall as a flat layered medium, whilst being significantly computationally cheaper than full-wave methods, strongly motivated by practical considerations for through-wall SAR.

Ultrafast 3-D Transcutaneous Super Resolution Ultrasound Using Row-Column Array Specific Coherence-Based Beamforming and Rolling Acoustic Sub-aperture Processing: In Vitro, in Rabbit and in Human Study

ObjectiveThis study aimed to realise 3-D super-resolution ultrasound imaging transcutaneously with a row-column array which has far fewer independent electronic channels and a wider field of view than typical fully addressed 2-D matrix arrays. The in vivo image quality of the row-column array is generally poor, particularly when imaging non-invasively. This study aimed to develop a suite of image formation and post-processing methods to improve image quality and demonstrate the feasibility of ultrasound localisation microscopy using a row-column array, transcutaneously on a rabbit model and in a human. MethodsTo achieve this, a processing pipeline was developed which included a new type of rolling window image reconstruction, which integrated a row-column array specific coherence-based beamforming technique with acoustic sub-aperture processing. This and other processing steps reduced the ‘secondary’ lobe artefacts, and noise and increased the effective frame rate, thereby enabling ultrasound localisation images to be produced. ResultsUsing an in vitro cross tube, it was found that the procedure reduced the percentage of ‘false’ locations from ∼26% to ∼15% compared to orthogonal plane wave compounding. Additionally, it was found that the noise could be reduced by ∼7 dB and the effective frame rate was increased to over 4000 fps. In vivo, ultrasound localisation microscopy was used to produce images non-invasively of a rabbit kidney and a human thyroid. ConclusionIt has been demonstrated that the proposed methods using a row-column array can produce large field of view super-resolution microvascular images in vivo and in a human non-invasively.

Whole Reconstruction-Free System Design for Direct Positron Emission Imaging From Image Generation to Attenuation Correction.

Direct positron emission imaging (dPEI), which does not require a mathematical reconstruction step, is a next-generation molecular imaging modality. To maximize the practical applicability of the dPEI system to clinical practice, we introduce a novel reconstruction-free image-formation method called direct μCompton imaging, which directly localizes the interaction position of Compton scattering from the annihilation photons in a three-dimensional space by utilizing the same compact geometry as that for dPEI, involving ultrafast time-of-flight radiation detectors. This unique imaging method not only provides the anatomical information about an object but can also be applied to attenuation correction of dPEI images. Evaluations through Monte Carlo simulation showed that functional and anatomical hybrid images can be acquired using this multimodal imaging system. By fusing the images, it is possible to simultaneously access various object data, which ensures the synergistic effect of the two imaging methodologies. In addition, attenuation correction improves the quantification of dPEI images. The realization of the whole reconstruction-free imaging system from image generation to quantitative correction provides a new perspective in molecular imaging.

Formation of the image of organizations

The purpose of the article is to consider some theoretical aspects of the formation of the image of organizations. The article provides a definition of the concept, purpose, and functions of the organization's image; the subjects, the structure of the image, as well as the means and methods of its formation are indicated. It has been established that the main means of forming and maintaining the image of an organization are marketing communications: corporate identity, visual and verbal means, advertising, and PR events. Three main methods of image formation are identified: production, image-making, and managerial methods. The characteristics of the types and levels of image are given; an algorithm for forming the image of the organization and the goods it sells or services it provides is determined.

Principles for training PR specialists in libraries (new requirements for the training of industry specialists)

The main purpose of the article is to explore the principles of training PR specialist in libraries. Thus, changes in the socio-economic life of modern society require qualitative transformations in the nature and content of labor, an increase in the level of socio-psychological mobility, and the competitiveness of specialists working in various fields of industrial and social activities. Vocational education is designed to meet the need for human resources in the economic and social spheres. Additionally, in the educational practice of Azerbaijan, the concept "specialist" has long been interpreted as a graduate who has achieved knowledge and success as a result of mastering an educational program. In the context of this work, a librarian is considered a practical librarian who has a special education and is competent in the field of professional librarianship, regardless of the training level (bachelor's, master's). Methods: The article is based on the method of comparative analysis. Application importance: the material can be used in lecturers and seminars in higher education institutions (HEIs). Libraries occupy a large place among non-profit organizations involved in PR activities. Primarily because it has a wide structured network throughout the country. Also, the public trusts the sincerity of the activities of this institution as a non-profit enterprise. It is from this point of view that it is important to use PR technologies and methods of image formation in the process of training specialists. When organizing library and information activities, along with the promotion of existing products and enterprise capabilities by means of PR, such tasks as maintaining a reliable image are also solved. The training of highly qualified library and information specialists in this direction is accompanied by an increase in their demand in the labor market. The article analyzes the issues of training highly qualified specialists in the direction of library and information activities, as competent personnel in the field of PR and in the direction of image formation. It is also important to study viewpoints and research of experienced scientists on this topic, as well as to analyze the experience of leading enterprises in the field of industry. To sum up, we would like to draw the attention of industry experts to the concept proposed in the article.

Inspection of cargo using dual-energy X-ray radiography: A review

Cargo inspection is essential for material discrimination and security aims such as threat detection/identification. In this paper, dual-energy X-ray imaging for cargo inspection is studied. Dual-energy imaging challenges such as improving image quality (i.e. noise reduction), automatically removing image defects and errors, and developing algorithms for image detection and identification are investigated. Selecting the right method for image formation, selecting the right source, choosing appropriate X-ray energies, and the appropriate detectors are also discussed. Cargo inspection using dual-energy X-ray shows that not many techniques have been presented for denoising, and there is no comparative comparison between them. Material discrimination using dual-energy X-ray has had significant success in cargo, especially when convolutional neural network (CNN) is integrated with traditional techniques. However, it will have limitations on performance due to the existence of challenges such as the need for large data and the possibility of noise presence in the extracted features. It seems that future studies should cover these issues.

The contralateral organization of the human nervous system as a quantum unfolded, holographic-like, artifactual representation of the underlying dynamics of a fundamentally two-dimensional universe.

A working hypothesis is put forward in this article that the contralateral organization of the human nervous system appears to function like a quantum unfolded holographic apparatus by appearing to invert and reverse quantum unfolded visual and non-visual spatial information. As such, the three-dimensional contralateral organization would be an artifactual representation of the underlying dynamics of a fundamentally two-dimensional universe. According to the holographic principle, nothing that is experienced as three-dimensional could have been processed in a three-dimensional brain. Everything we would experience at a two-dimensional level would appear as a three-dimensional holographic representation, including the architecture of our brains. Various research observations reported elsewhere are reviewed and interpreted here as they may be related in a process that is fundamental to the underlying two-dimensional dynamics of the contralateral organization. The classic holographic method and characteristics of image formation contained by a holograph are described as they relate to the working hypothesis. The double-slit experiment is described and its relevance to the working hypothesis.

Sub-aperture SAR imaging with uncertainty quantification

In the problem of spotlight mode airborne synthetic aperture radar (SAR) image formation, it is well-known that data collected over a wide azimuthal angle violate the isotropic scattering property typically assumed. Many techniques have been proposed to account for this issue, including both full-aperture and sub-aperture methods based on filtering, regularized least squares, and Bayesian methods. A full-aperture method that uses a hierarchical Bayesian prior to incorporate appropriate speckle modeling and reduction was recently introduced to produce samples of the posterior density rather than a single image estimate. This uncertainty quantification information is more robust as it can generate a variety of statistics for the scene. As proposed, the method was not well-suited for large problems, however, as the sampling was inefficient. Moreover, the method was not explicitly designed to mitigate the effects of the faulty isotropic scattering assumption. In this work we therefore propose a new sub-aperture SAR imaging method that uses a sparse Bayesian learning-type algorithm to more efficiently produce approximate posterior densities for each sub-aperture window. These estimates may be useful in and of themselves, or when of interest, the statistics from these distributions can be combined to form a composite image. Furthermore, unlike the often-employed -regularized least squares methods, no user-defined parameters are required. Application-specific adjustments are made to reduce the typically burdensome runtime and storage requirements so that appropriately large images can be generated. Finally, this paper focuses on incorporating these techniques into SAR image formation process, that is, for the problem starting with SAR phase history data, so that no additional processing errors are incurred. The advantage over existing SAR image formation methods are clearly presented with numerical experiments using real-world data.

Editorial: Advances in image formation methods for optoacoustic and ultrasound imaging

Editorial: Advances in image formation methods for optoacoustic and ultrasound imaging

Joint Demosaicing and Fusion of Multiresolution Coded Acquisitions: A Unified Image Formation and Reconstruction Method

Novel optical imaging devices allow for hybrid acquisition modalities such as compressed acquisitions with locally different spatial and spectral resolutions captured by the same focal plane array. In this work, we propose to model a multiresolution coded acquisition (MRCA) in a generic framework, which natively includes acquisitions by conventional systems such as those based on spectral/color filter arrays, compressed coded apertures, and multiresolution sensing. We propose a model-based image reconstruction algorithm performing a joint demosaicing and fusion (JoDeFu) of any acquisition modeled in the MRCA framework. The JoDeFu reconstruction algorithm solves an inverse problem with a proximal splitting technique and is able to reconstruct an uncompressed image datacube at the highest available spatial and spectral resolution. An implementation of the code is available at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://github.com/danaroth83/jodefu</uri> .

Advanced Topics in Quantitative Acoustic Microscopy.

Quantitative acoustic microscopy (QAM) reconstructs two-dimensional (2D) maps of the acoustic properties of thin tissue sections. Using ultrahigh frequency transducers (≥ 100 MHz), unstained, micron-thick tissue sections affixed to glass are raster scanned to collect radiofrequency (RF) echo data and generate parametric maps with resolution approximately equal to the ultrasound wavelength. 2D maps of speed of sound, mass density, acoustic impedance, bulk modulus, and acoustic attenuation provide unique and quantitative information that is complementary to typical optical microscopy modalities. Consequently, many biomedical researchers have great interest in utilizing QAM instruments to investigate the acoustic and biomechanical properties of tissues at the micron scale. Unfortunately, current state-of-the-art QAM technology is costly, requires operation by a trained user, and is accompanied by substantial experimental challenges, many of which become more onerous as the transducer frequency is increased. In this chapter, typical QAM technology and standard image formation methods are reviewed. Then, novel experimental and signal processing approaches are presented with the specific goal of reducing QAM instrument costs and improving ease of use. These methods rely on modern techniques based on compressed sensing and sparsity-based deconvolution methods. Together, these approaches could serve as the basis of the next generation of QAM instruments that are affordable and provide high-resolution QAM images with turnkey solutions requiring nearly no training to operate.

Focusing dynamic single‐channel synthetic aperture radar video with optical flow‐informed reconstruction

The motion of targets is well known to result in their defocusing and displacement in SAR imagery, but detection of motion and re-focusing of targets under generic conditions remains an ongoing interest. One class of methods involves forming images of sub-apertures in which motion defocusing will be reduced. In this paper, dynamic tomographic image formation methods utilising an optical flow constraint is used to form a video of SAR sub-aperture images. These retain fine resolution of the full aperture, focusing along-track motion.

Space-Based Sub-THz ISAR for Space Situational Awareness - Laboratory Validation

The advantages of sub-terahertz technology (sub-THz, 200–700 GHz) have already been advanced for imaging and recognition of a space object's state from a space-based sensor using inverse synthetic aperture radar (ISAR). The technology benefits from wide absolute signal bandwidths, giving high range resolution and from enhanced sensitivity to surface texture. An experimental validation of such a system in controlled laboratory conditions is presented. Possible image formation methods are proposed and evaluated experimentally. Images of real parts of satellites have been produced at sub-THz frequencies and compared to lower frequency images. Other results include sub-THz bistatic ISAR, and sub-THz cross-polarized images which highlight the scattering from rough surfaces while attenuating the very bright scatterers seen from conventional monostatic images.

Prediction of Alzheimer's Disease by a Novel Image-Based Representation of Gene Expression.

Early intervention can delay the progress of Alzheimer’s Disease (AD), but currently, there are no effective prediction tools. The goal of this study is to generate a reliable artificial intelligence (AI) model capable of detecting the high risk of AD, based on gene expression arrays from blood samples. To that end, a novel image-formation method is proposed to transform single-dimension gene expressions into a discriminative 2-dimensional (2D) image to use convolutional neural networks (CNNs) for classification. Three publicly available datasets were pooled, and a total of 11,618 common genes’ expression values were obtained. The genes were then categorized for their discriminating power using the Fisher distance (AD vs. control (CTL)) and mapped to a 2D image by linear discriminant analysis (LDA). Then, a six-layer CNN model with 292,493 parameters were used for classification. An accuracy of 0.842 and an area under curve (AUC) of 0.875 were achieved for the AD vs. CTL classification. The proposed method obtained higher accuracy and AUC compared with other reported methods. The conversion to 2D in CNN offers a unique advantage for improving accuracy and can be easily transferred to the clinic to drastically improve AD (or any disease) early detection.

Space-Based Sub-THz ISAR for Space Situational Awareness—Concept and Design

The concept of sub-terahertz (sub-THz) imaging and recognition of space objects by a satellite-based inverse synthetic aperture radar (ISAR) is proposed and analyzed in this article. Operation at sub-THz frequencies in the band 200–400 GHz benefits from wide available bandwidth, high sensitivity to surface texture, and very small target features, and requires an antenna of small physical size. A feasibility study is presented based on use case scenarios of the relative motion of monitoring satellite and observed objects. Expected resolutions, power budget, and oscillator stability requirements in this frequency band are discussed. Image formation methods are proposed and evaluated with simulations. A simple electromagnetic modeling capability is proposed to create a comprehensive dataset of sub-THz ISAR images, with the orientation and aspect angles seen by the sensors, which can be used to train semantic classifiers.

Despeckling of OCT images using DT-CWT based fusion technique

Optical Coherence Tomography (OCT) is a non-invasive diagnostic method used to identify and manage a variety of retinal illnesses. However, the OCT image formation method gives rise to speckle noise that can drastically degrade the quality of OCT images. These low-quality images have a detrimental effect on subsequent illness diagnoses. There are numerous software-based speckle reduction techniques, each with its own advantages. Hence, combining even some of them maximizes the benefits. We propose a fusion approach based on spatial domain filtering and a sparsity-based denoising method for speckle noise removal in OCT images. Our hybrid methodology employs the Dual-Tree Complex Wavelet Transform (DT-CWT) to integrate both spatial domain filtering and the sparsity-based denoising method and uses a multi-scale fusion technique to merge the two transformed output images. Experimental findings indicate that the proposed algorithm could successfully combine two images, resulting in an output OCT image with significant speckle reduction and image structure preservation.

INFORMATION REPRODUCTION SYSTEMS IN INFORMATION BUSINESS LOGISTICS

The article considers the fundamentals of the information reproduction systems formation in the optoelectronic element base for information logistics systems. The use of optoelectronic elements for information processing has been considered, namely discrete optoelectronic digital systems, analog systems, optical memory systems, optical systems of input-output of information in computers, systems based on fiber devices of neuristor type. It is emphasized that modern logistics is impossible without the active use of information technology. The functions of information support of managerial influences can be performed by information technologies used today in logistics. To perform the tasks of financial flow management, these technologies can be supplemented by modules of eye-processing of the information. Logic-clock quantron automatic devices based on optocouplers are suitable for creating parallel information operating environments, which is a universal means of converting and presenting information. This approach leads to the creation of matrix-type devices that are able not only to receive information but also to process it. One of the promising areas of use of optoelectronic matrix systems is the creation of flat operating screens for parallel reception and display of information. The paper presents the classification of operating screens according to such features as: the principle of displaying information, the type of input information, the type of output information, the method of image formation, the number of consumers of the information. The analysis of electric circuit diagram of modern LED matrix video screens, in particular of a typesetting-modular design has been presented. A comparison of the forms of organization of matrix video screens is made, and it is emphasized that the most economical in terms of the number of memory trigger elements per one LED of the display cell is a video information system based on the structure of the third group video screen. The structure of the video information system is optimized according to the criterion of optimality – the maximum image quality on the matrix screen and the minimum screen complexity, which is determined by the circuit features of the microelectronic circuits.

A method of quasi-continuous image formation in observation devices with discrete receivers

The article proposes a new method of quasi-continuous image formation in observation devices with discrete receivers. The increase in the number of spatial sampling points in the object image is provided by intraframe scanning. Scanning is carried out by a photosensitive matrix with a regularly changed (controlled) density of the elementary receivers (CDR-matrix). The CDR-matrix contains identical elementary receivers. They are regularly distributed over the matrix surface. The vertical and horizontal distance between adjacent receivers is a multiple of the size of the elementary receiver. The CDR-matrix becomes equivalent in pixel dimensions to a larger photosensitive matrix. The magnitude of the multiplicity placement of the receivers is chosen by the developer when designing the light-sensitive matrix. The image of the object by the CDR-matrix (a separate frame) is composed of a series of snapshots. Each snapshot is formed by signals coming from all elementary receivers of the CDR-matrix. The number of snapshots in the frame is set by the multiplicity of the size of the elementary receivers vertically and horizontally. While using intraframe scanning, the CDR-matrix with a pixel size of the video format can operate in the mode of a photosensitive matrix with a pixel size of 2.5 MP. A CDR-matrix with a pixel size of 6 MP can operate as a 48 MP matrix of a conventional design. A mechanism for storing a frame with observation results when using a CDR-matrix is proposed. It assumes the use of the matrix addition operation. The signal matrix of the observed frame is considered as the sum of the signal matrices of all the snapshots in the frame. Application of the developed method will make it possible to multiply the pixel size of the image relative to the pixel size of the controllable photosensitive matrix. The advantages of the proposed method also include the absence of a mandatory decrease in the effective area of an elementary receiver with an increase in their number in the photosensitive matrix; simplification of hardware measures to reduce the effect of image shift on its quality; absence of information losses in the intervals between adjacent elementary receivers.

Histogram Matching for Visual Ultrasound Image Comparison.

The widespread development of new ultrasound image formation techniques has created a need for a standardized methodology for comparing the resulting images. Traditional methods of evaluation use quantitative metrics to assess the imaging performance in specific tasks, such as point resolution or lesion detection. Quantitative evaluation is complicated by unconventional new methods and nonlinear transformations of the dynamic range of data and images. Transformation-independent image metrics have been proposed for quantifying task performance. However, clinical ultrasound still relies heavily on visualization and qualitative assessment by expert observers. We propose the use of histogram matching to better assess differences across image formation methods. We briefly demonstrate the technique using a set of sample beamforming methods and discuss the implications of such image processing. We present variations of histogram matching and provide code to encourage the application of this method within the imaging community.

SAR Image Formation Method with Azimuth Periodically Missing Data Based on RELAX Algorithm

Synthetic aperture radar (SAR) is a widely used remote sensing observation technique. However, SAR raw echo data may be lost during the process of data acquisition by radar platform. In this paper, the imaging problem of SAR echo signal with periodically missing data along the azimuth is analyzed and a novel imaging method is proposed. Firstly, the problem of artificial artifact targets caused by periodically missing data is explained in detail, and the corresponding mathematical model is established. Then, the recovery method based on the RELAX algorithm with periodic notches data is proposed. In addition, when the size of two-dimensional (2D) echo data are large, block restoration along the azimuth is proposed to reduce the amount of calculation. Finally, the advantages of the algorithm proposed in this paper is demonstrated by the points target simulated SAR echo data processing and the real raw SAR echo data processing. When the azimuth periodically missing data rate is 50%, the SAR echo data can be recovered and the well-focused image can be obtained. Comparing the image entropy value and structural similarity index (SSIM) of the focused image, it proves the superiority of the proposed algorithm in solving the imaging problem of SAR azimuth periodically missing data.