Principles Of Image Formation Research Articles

Casting shadows on the eye to reveal the inverted retinal image

ABSTRACT We introduce and discuss an entoptic effect that helps to demonstrate that images on the retina are optically inverted and reversed. This simple consequence of geometric optics can seem somewhat abstract to students, but this effect is vivid, surprising, and links optical principles to students’ own subjective experience of seeing. Moreover, it requires nothing more than a bright light source, an opaque card that can be punctured to create a pinhole, and a pencil, pen, or other instrument with a fine tip. The phenomenon is not new, but we present it here in the hopes that it becomes more widely known and used in perception science instruction. We describe the necessary setup to achieve the effect, key observations, and briefly outline an explanation. We also contextualize the effect in historical discussion and observations of the inverted retinal image, including discussion of the pedagogical use of pinhole cameras in vision science instruction. Overall, this effect provides a simple yet dramatic demonstration of basic principles of image formation in the human eye.

Таблично-алгоритмічний метод для антиаліайзингу зображення відрізків прямих

Increasing the informativeness of computer graphics is achieved due to the formation of images that accurately reproduce the structural and visual features of the object. When forming such images, it is necessary to display graphic scenes with great detail, therefore, at this stage of the development of computer graphics, special attention is paid not only to the speed of forming graphic images, but also to their realism. In most modern computer graphics systems, the raster principle of image formation is used. When creating raster images, distortions occur due to the insufficient resolution of the raster. Artifacts appear on the images, one of the manifestations of which are pronounced steps or teeth on the edges of objects. The aliasing effect significantly affects the realism of the formed image, which necessitates the development of special methods and means of its elimination The tabular method of vector anti-aliasing was further developed. It is proposed to calculate the values of the evaluation function to store its values with a larger quantization step, and to calculate the intermediate ones according to the derived formula. The analysis showed that the use of the proposed approach allows reducing by 8¸17 times the amount of memory needed to calculate the pixel coverage area. The method involves hardware and software implementation and can be used in high-performance computer graphics systems.

Underwater Image Enhancement Based on Zero-Reference Deep Network

Due to underwater light absorption and scattering, underwater images usually suffer from severe color attenuation and contrast reduction. Most mainstream underwater image processing methods based on deep learning require a large amount of underwater paired training data, leading to a complex network structure, longer training time, and higher computational cost. To address this problem, a novel Zero-Reference Deep Network for Underwater Image Enhancement (Zero-UIE) is proposed in this paper, which transforms the enhancement of an underwater image into a specific parameter map estimation by using a deep network. The underwater curve model based on the classical haze image formation principle is specially designed to remove underwater color dispersion and cast. A lightweight deep network is designed to estimate the dynamic adjustment parameters of the underwater curve model, and then adjust the dynamic range of the given image pixels according to the model. A set of non-reference loss functions are designed according to the characteristics of underwater images, which can implicitly drive the network learning. In addition, adaptive color compensation can be optionally used as the pre-processing step to further improve the robustness and visual performance. The significant contribution of the proposed method is zero reference, i.e., it does not require any paired or unpaired reference data for training. Extensive experiments on various benchmarks demonstrate that the proposed method is superior to state-of-the-art methods subjectively and objectively, which is competitive and applicable to diverse underwater conditions. Most importantly, it is an innovative exploration of zero reference for underwater image enhancement.

Inverse Hartmann test for radius of curvature measurement in a corneal topography calibration sphere

In this article, the use of a square Hartmann screen test to measure the radius of curvature of a corneal topography calibration test sphere is presented. The proposed technique is based on the image formation principle by specular reflection on convex reflective surfaces. Applying an inverse Hartmann test, a de-magnified virtual image (Hartmanngram) is obtained; considering their own scaled reference screen plate, a zonal wavefront retrieval approach is used and the radius of curvature obtained. Experimental setup along the obtained results is presented. A simulated spherical wavefront is used as a method to evaluate the error in the wavefront reconstruction. Since the measurements of radius of curvature fits in to ISO 10343, through suitable modifications the proposed method is potentially applicable in small F/# convex specular surfaces, as is the case in keratometry and corneal topography measurements.

ОРГАНІЗАЦІЙНО-ЕКОНОМІЧНІ ЗАСАДИ ФОРМУВАННЯ КОРПОРАТИВНОГО ІМІДЖУ ТОРГОВЕЛЬНОГО ПІДПРИЄМСТВА

The article examines the essence and characteristics of the corporate image. The main elements of the corporate image are: the main business and financial indicators of the enterprise; reputation and performance of brands; reputation for innovation or technological superiority, which, as a rule, is based on specific events; enterprise policy regarding hired employees and workers; external relations with clients, shareholders and the community; perceived trends in the markets in which the enterprise operates and how the public sees it. The principles of corporate image formation are revealed, and its structure is given. The main tasks for maintaining the image of the enterprise are defined. It is noted that the image must be formed in the internal environment in order to create a single system that will be aimed at creating the loyalty of all audiences, and formed in the external environment – to strengthen trust and affection. It is noted that the structure of the corporate image is a combination of internal and external image. The external image is the assessment of the company by the external community, and the internal image is formed on the basis of the collective opinion of the personnel of this organization. At the same time, the external image is not homogeneous, it has its own specificity. The internal image, as a rule, is homogeneous. Emphasis is placed on the fact that the creation of a good corporate image campaign should include a strategic communication plan that should take into account all forms of communication. The formation of a positive corporate image becomes a stimulating force for the operation and development of the enterprise. It is achieved by relying on various visual and verbal components that create a holistic image and impression that contributes to the competitiveness of the organization. A visual image is a representation of the organization and its activities for perception, which is better remembered and longer in people's memory. Verbal components are text and speech communications that provide non-commercial informational and reference material that shows the internal and external activities of the organization, and contributes to gaining positive fame and recognition. The main purpose of corporate image management is communication with interested parties, manifestation of uniqueness and formation of corporate style. One of the ways to form a corporate image is to establish and maintain positive relations with the general public. It is noted that the corporate image is best considered in conjunction with the vision and culture of the organization. Measures are proposed to support a positive corporate image of a trading enterprise. Emphasis is placed on the fact that it is necessary to focus attention on employees, as they form the opinion of consumers during appeals, consultations, advice, product presentations, communication, and calculation. At such moments, the employee must understand that he is responsible for the impression he leaves as a result of his work, and this impression is not only about him, but also about the work of the entire trade enterprise.

BACKGROUND-ORIENTED SCHLIEREN FOR FLOW AND THERMAL SYSTEMS: PRINCIPLES OF IMAGE FORMATION AND APPLICATIONS

Imaging fluid flow and transport phenomena has gained considerable attention in the recent past. The imaging techniques are not only limited to visualization tools but, when coupled with suitable data reduction algorithms, can lead to the generation of the complete whole field quantitative data of flow and transported properties. In this direction, the technique of background-oriented schlieren (BOS) is one of the latest developments that has garnered significant attention among the research community. The present article reviews the plausible configurations of the BOS system, including principles of image formation and its applications in the domain of flow and thermal systems. Particular attention is paid to various constraints that one faces while configuring the imaging technique correctly from its first principles and those associated with the development of data reduction methodologies for BOS image analysis. Various modifications affected in the standard BOS, since the time it was proposed by Meier et al. (2002, 2013), for mapping the flow and transported properties as well as thickness variations of liquid surfaces are reviewed. Following an extensive review of the available literature, the potential of BOS in imaging single- as well as two-phase heat transfer phenomena is demonstrated by setting up lab-based test configurations that include natural convection over a heated vertical flat plate and horizontally placed circular cylinder, and the evaporation dynamics of impinging acetone droplet(s). The recorded BOS images are quantitatively analyzed to retrieve the field distribution of parameters of interest in each of the configurations studied.

Distortion Convolution Module for Semantic Segmentation of Panoramic Images Based on the Image-Forming Principle

Semantic segmentation of panoramic images plays a key role in many applications, such as security monitoring and autonomous driving. With the rapid development of deep learning, some deep networks are developed to segment panoramic images semantically. However, these networks don’t have the special modules to correct the image distortion of panoramic images according to the distortion principle, which makes feature extraction unreasonable during the convolution because of the image distortion. This article proposes a novel semantic segmentation network for panoramic images of outdoor scenes based on the distortion convolution. The network contains an encoder and a decoder. The encoder consists of a distortion convolutional module (DCM), a residual network, and an atrous spatial pyramid pooling (ASPP). The DCM is developed to correct the image distortion according to the image-forming principle. In the decoder, a deep feature aggregation network (DFAN) is designed to fully fuse low-level features with high-level features. The proposed network introduces the DCM and DFAN into the semantic segmentation of panoramic images, which improves the segmentation accuracy. The experiments demonstrate that the proposed network has good performance for different outdoor scenes and plays an important role in measurement applications.

Reconstruction of Orthographic Mosaics From Perspective X-Ray Images.

Image stitching is a prominent challenge in medical imaging, where the limited field-of-view captured by single images prohibits holistic analysis of patient anatomy. The barrier that prevents straight-forward mosaicing of 2D images is depth mismatch due to parallax. In this work, we leverage the Fourier slice theorem to aggregate information from multiple transmission images in parallax-free domains using fundamental principles of X-ray image formation. The details of the stitched image are subsequently restored using a novel deep learning strategy that exploits similarity measures designed around frequency, as well as dense and sparse spatial image content. Our work provides evidence that reconstruction of orthographic mosaics is possible with realistic motions of the C-arm involving both translation and rotation. We also show that these orthographic mosaics enable metric measurements of clinically relevant quantities directly on the 2D image plane.

Software Implementation of Gesture Recognition Algorithm Using Computer Vision

This paper examines the main methods and principles of image formation, display of the sign language recognition algorithm using computer vision to improve communication between people with hearing and speech impairments. This algorithm allows to effectively recognize gestures and display information in the form of labels. A system that includes the main modules for implementing this algorithm has been designed. The modules include the implementation of perception, transformation and image processing, the creation of a neural network using artificial intelligence tools to train a model for predicting input gesture labels. The aim of this work is to create a full-fledged program for implementing a real-time gesture recognition algorithm using computer vision and machine learning.

Reverberant Shear Wave Elastography: A Multi-Modal and Multi-Scale Approach to Measure the Viscoelasticity Properties of Soft Tissues

There are a variety of approaches used to create elastography images. Techniques based on shear wave propagation have received significant attention. However, there remain some limitations and problems due to shear wave reflections, limited penetration in highly viscous media, requirements for prior knowledge of wave propagation direction, and complicated propagation in layers where surface acoustic waves and guided waves are dominant. To overcome these issues, reverberant shear wave elastography (RSWE) was proposed as an alternative method which applies the concept of a narrow-band diffuse field of shear waves within the tissue. Since 2017, the RSWE approach has been implemented in ultrasound (US) and optical coherence tomography (OCT). Specifically, this approach has been implemented in these imaging modalities because they are similar in image formation principles and both share several approaches to estimate the biomechanical properties in tissues. Moreover, they cover different spatial-scale and penetration depth characteristics. RSWE has shown promising results in the elastic and viscoelastic characterization of multiple tissues including liver, cornea, and breast. This review summarizes the 4-year progress of the RSWE method in US and OCT. Theoretical derivations, numerical simulations, and applications inex vivoandin vivotissues are shown. Finally, we emphasize the current challenges of RSWE in terms of excitation methods and estimation of biomechanical parameters for tissue-specific cases and discuss future pathways for thein vivoandin situclinical implementations.

Generative Adversarial Network for Image Raindrop Removal of Transmission Line Based on Unmanned Aerial Vehicle Inspection

In the process of UAV line inspection, there may be raindrops on the camera lens. Raindrops have a serious impact on the details of the image, reducing the identification of the target transmission equipment in the image, reducing the accuracy of the target detection algorithm, and hindering the practicability of UAV line inspection technology in cyber‐physical energy systems. In this paper, the principle of raindrop image formation is studied, and a method of raindrop removal based on generation countermeasure network is proposed. In this method, the attention recurrent network is used to generate the raindrop attention map, and the context code decoder is used to generate the raindrop image. The experimental results show that the proposed method can remove the raindrops in the image and repair the background image of raindrop coverage area and can generate a higher quality raindrop removal image than the traditional method.

Становление творческой личности А. С. Пушкина в зеркале романа Ю. Н. Тынянова «Пушкин»

The features of the image of the formation of Alexander Pushkin’s creative personality in Yu. Tynyanov’s novel “Pushkin” are investigated. The question of realization Yu. Tynyanov’s creative concept in this work is raised. Tynyanov sought to escape from the prevailing of the absolutization of the individual and the work of the poet in literary studies of the time and create his own interpretation based on comparative historical and formal approaches. The author of the article points out that the writer depicts the poet as an unusual child deprived of love and understanding of relatives and, as a consequence, lonely. Attention of Yu. Tynianov to the origins of the creative personality is emphasized. It is shown that the writer refers to the description of how the boy masters the art of watching and reflecting, how he awakens the love of literature and folk art, develops a tendency to poetry. It is noted that Yu. Tynyanov’s interpretation of Pushkin’s childhood is sometimes distressing, but in the description of the youth perspective of the narrative changes: in Lyceum, overcoming the drama of his awareness of the differences from others, the young poet begins to understand the value and purpose of creative personality. The conclusion about the links between the principles of image formation of the poet’s personality and Yu. Tynyanov’s concept of historicity is made.

Tomographic diffractive microscopy: Towards high-resolution 3-D real-time data acquisition, image reconstruction and display of unlabeled samples

Tomographic diffractive microscopy allows for imaging unlabeled specimens, with a better resolution than conventional microscopes, giving access to the index of refraction distribution within the specimen, and possibly at high speed. Principles of image formation and reconstruction are presented, and progresses towards real-time, three-dimensional acquisition, image reconstruction and final display, are discussed.

Vibration error-compensation technique in phase shifting moiré interferometry

Undesirable vibrations can greatly degrade the accuracy of phase shifting moire interferometry. Although moire interferometry is always equipped with a somehow elaborate system to dampen or to eliminate vibration, such as granite slab and air table, it is common to see the phase fluctuation of moire diagram attributable to the various vibration during the measurement process. The sensitivity of moire interferometry to vibration is rooted in the fundamental principles of the instrument. Typically, an imaging system collects interference patterns for a sequence of reference phases, and then a computer unwraps the original wave-front phase by analyzing the variations of intensity. Compared with classical interferometry, an experiment by grating rosette moire interferometry with different principle of image formation is carried out and a corresponding efficient phase calculation method is developed to eliminate or compensate the effects of mechanical vibrations. In the decomposition and reconstitution of phase-shifting fringe patterns using discrete Fourier series, the phase-shifting fundamental coefficients (a 0, a 1 and b 1) are extracted from 10 samples in one phase shift cycle, with which three images with 120 degree intervals are obtained. Besides, a mathematical model for the phase error is derived by vibration frequency content or spectrum. Combined with traditional phase shifting algorithm, the proposed data post-processing technique can effectively reduce the phase ripple caused by vibrations. The result is supported by numerical simulations in MATLAB software and experiments with grating rosette moire interferometry.

Principle of MRI Image Formation

Principle of MRI Image Formation

Ultrasound Imaging Velocimetry: a review

Whole-field velocity measurement techniques based on ultrasound imaging (a.k.a. ‘ultrasound imaging velocimetry’ or ‘echo-PIV’) have received significant attention from the fluid mechanics community in the last decade, in particular because of their ability to obtain velocity fields in flows that elude characterisation by conventional optical methods. In this review, an overview is given of the history, typical components and challenges of these techniques. The basic principles of ultrasound image formation are summarised, as well as various techniques to estimate flow velocities; the emphasis is on correlation-based techniques. Examples are given for a wide range of applications, including in vivo cardiovascular flow measurements, the characterisation of sediment transport and the characterisation of complex non-Newtonian fluids. To conclude, future opportunities are identified. These encompass not just optimisation of the accuracy and dynamic range, but also extension to other application areas.

On the link between the speckle free nature of optoacoustics and visibility of structures in limited-view tomography

Similar to pulse-echo ultrasound, optoacoustic imaging encodes the location of optical absorbers by the time-of-flight of ultrasound waves. Yet, signal generation mechanisms are fundamentally different for the two modalities, leading to significant distinction between the optimum image formation strategies. While interference of back-scattered ultrasound waves with random phases causes speckle noise in ultrasound images, speckle formation is hindered by the strong correlation between the optoacoustic responses corresponding to individual sources. However, visibility of structures is severely hampered when attempting to acquire optoacoustic images under limited-view tomographic geometries. In this tutorial article, we systematically describe the basic principles of optoacoustic signal generation and image formation for objects ranging from individual sub-resolution absorbers to a continuous absorption distribution. The results are of relevance for the proper interpretation of optoacoustic images acquired under limited-view scenarios and may also serve as a basis for optimal design of tomographic acquisition geometries and image formation strategies.

An equation-free introduction to post-mortem MR image contrast and pulse sequence optimization

Abstract Due to the excellent sensitivity of Magnetic Resonance (MR) imaging to subtle differences in soft tissues, MR enables non-invasive anatomical imaging with superior soft tissue contrast relative to X-ray Computed Tomography (CT). However, relative to the X-ray modalities, the utility of MR in the post-mortem setting is currently less well-defined. MR is significantly different from the X-ray modalities, in terms of the underlying principles of image formation, the equipment and expertise necessary to acquire the images, and the appearance of the images themselves. Because MR is sensitive to subtle differences in soft tissues, factors unique to the post-mortem setting, particularly variations in body temperature, tend to have a greater effect on MR imaging relative to the X-ray modalities. Fortunately, MR is inherently flexible and adaptable; there are many types of MR protocols, each with user-controlled parameters that can be adjusted to achieve the best imaging of a specific pathology or anatomic structure, at a given temperature or post-mortem interval (PMI). Optimizing, validating, and standardizing post-mortem MR (PMMR) protocols represents a challenging yet achievable long-term goal. For those interested in developing a better understanding of how to optimize PMMR image quality, this review is intended to provide some guidance, from a technical (but non-mathematical) perspective. A practical explanation of basic pulse sequences and MR relaxation times, and their relationship to tissue contrast, is provided. Strategies for optimizing PMMR for forensic imaging applications, suitable for users with varying levels of expertise, are discussed in the context of current progress in this area.

TH-AB-210-01: Basics of Gamma Camera Operations and Quality Assurance

This education session will cover the basic physics and operation principles of gamma cameras and PET scanners. In addition, quality control tests to assure good image quality are described. The first talk will discuss the components of gamma cameras, image formation principles, and performance characteristics, such as spatial resolution, sensitivity, and energy resolution. Features that affect these performance characteristics will be discussed. Physicists are increasingly expected to perform annual performance tests on gamma cameras, not only as good practice, but to satisfy requirements of accrediting bodies or for insurance reimbursement. The Joint Commission has recently introduced changes in standards for accredited entities providing diagnostic imaging services, including nuclear medicine. Basic performance tests suitable for annual physics testing will be discussed. Learning Objectives: 1. Be able to describe basic principles of gamma camera operation. 2. Learn about performance characteristics and features affecting image quality. 3. Be able to list some basic performance tests for gamma cameras, how to perform the tests and evaluate acceptable performance. The second talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: 1. Be able to describe basic physics principles of PET and operation of PET scanners. 2. Learn about recent advances in PET scanner hardware technology. 3. Be able to describe advances in reconstruction techniques and improvements 4. Be able to list relevant performance tests. Turkington: Research support from GE for PET work, and has served as a consultant for Data Spectrum Corp.

TH-AB-210-00: Nuclear Medicine 101

This education session will cover the basic physics and operation principles of gamma cameras and PET scanners. In addition, quality control tests to assure good image quality are described. The first talk will discuss the components of gamma cameras, image formation principles, and performance characteristics, such as spatial resolution, sensitivity, and energy resolution. Features that affect these performance characteristics will be discussed. Physicists are increasingly expected to perform annual performance tests on gamma cameras, not only as good practice, but to satisfy requirements of accrediting bodies or for insurance reimbursement. The Joint Commission has recently introduced changes in standards for accredited entities providing diagnostic imaging services, including nuclear medicine. Basic performance tests suitable for annual physics testing will be discussed. Learning Objectives: 1. Be able to describe basic principles of gamma camera operation. 2. Learn about performance characteristics and features affecting image quality. 3. Be able to list some basic performance tests for gamma cameras, how to perform the tests and evaluate acceptable performance. The second talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: 1. Be able to describe basic physics principles of PET and operation of PET scanners. 2. Learn about recent advances in PET scanner hardware technology. 3. Be able to describe advances in reconstruction techniques and improvements 4. Be able to list relevant performance tests. Turkington: Research support from GE for PET work, and has served as a consultant for Data Spectrum Corp.