Simulation Of Image Reconstruction Research Articles

Lissajous MEMS laser beam scanner with uniform and high fill-factor projection for augmented reality display.

MEMS Laser beam scanning (LBS) has been identified as a key advancement for augmented reality (AR) displays due to its ability to create compact optical systems that generate bright, high-contrast images with minimal heat dissipation. This innovation can be attributed to the focus-free, efficient light-on-demand pixel projection mechanisms integral to LBS. The LBS, specifically in Lissajous-mode, outperforms the raster-mode in terms of larger scan angles and stability to external vibrations, by leveraging a MEMS mirror operating at bi-axial resonance. However, it tends to be hampered by small mirror aperture, low fill-factor, and inconsistent uniformity of image projection. In this research, a unique gimbal-less Lissajous MEMS scanner was proposed. It employs a bi-axial high frequency of 12,255 Hz and 7,182 Hz to achieve a resolution of 640 × 360 pixels and a video refresh rate of 57 Hz, all while maintaining a high image fill factor of 85.11%. The robust structure of the mirror is proven to sustain stable scanning under broad spectrum of external vibration disturbance up to 2,000 Hz. Furthermore, the large mirror diameter of 2 mm improves refined pixel projection and increased optical etendue for exit pupil. Mathematic model of Lissajous pixel-cells and image reconstruction simulation were established to validate the LBS's ability to generate a uniform and densely pixelated visual effect that fits for typical AR head-up display (AR-HUD). In a pioneering move, performance metric of figure-of-merit was defined to evaluate AR light-engines using varied picture-generation techniques, laying a foundation for guiding future AR system development.

2D projection image reconstruction for field free line single-sided magnetic particle imaging scanner: simulation studies.

Magnetic Particle Imaging is an imaging modality that exploits the nonlinear response of superparamagnetic iron oxide nanoparticles to a time-varying magnetic field. In the past years, various scanner topologies have been proposed, which includes a single-sided scanner. Such a scanner features all its hardware located on one side, offering accessibility without limitations due to the size of the object of interest. In this paper, we present a proof of concept image reconstruction simulation studies for a single-sided field-free line scanner utilizing non-uniform magnetic fields. Specifically, we implemented a filtered backprojection algorithm allowing a 2D image reconstruction over a field of view of 4 × 4 cm2 with a spatial resolution of up to 2 mm for noiseless case.

A new adaptive-weighted total variation sparse-view computed tomography image reconstruction with local improved gradient information.

Inspired by the compressed sensing (CS) theory, introducing priori information of sparse image into sparse-view reconstruction algorithm of computed tomography (CT) can improve image quality. In recent years, as a special case of CS, total variation (TV) reconstruction algorithm that uses both image sparsity and prior information of edge direction have attracted much research interest in sparse-view image reconstruction due to its ability to preserve image edges. In this paper, we propose a new adaptive-weighted total variation (NAWTV) algorithm for CT image reconstruction, which is derived by considering local gradient direction continuity and the anisotropic edge property. The anisotropic edge property is used to consolidate the image sparsity, where the associated weights are expressed as a combination of exponential and cosine function. The weights can also be adjusted adaptively according the local image intensity gradient. The NAWTV algorithm is numerically implemented with gradient descent method. The typical Shepp-Logan phantom and FORBILD head phantom are employed to perform image reconstruction simulation. To evaluate performance of NAWTV algorithm, we compared it with TV and AwTV reconstruction algorithms in experiments. Numerical experimental results verified the effectiveness and feasibility of the proposed algorithm. Comparison results also showed that the NAWTV algorithm achieved a satisfactory performance in suppressing artifacts and preserving the edge structure details information of the reconstructed image.

Simulasi Rekonstruksi Citra Pada Sensor Brain ECVT (Electrical Capacitance Volume Tomography) dengan Metode ILBP (Iterative Linear Back Projection)

<p>The purpose of this study is to simulate the sensor 32-channel Brain ECVT image reconstruction using ILBP (Iterative Linear Back Projection) methods. ECVT is a dynamic volume imaging technique that utilizes non-linear difference of electric field distribution to determine the distribution of permittivity in the sensing area. ECVT has measured the capacitance of data as a result of changes in the permittivity distribution between the electrode pairs. ECVT device consists of three main parts: helmet-shaped sensors, DAS (Data Acquisition System), PC for display and image reconstruction process. Simulation of sensor design using COMSOL Multiphysics 3.5 software, while the process of image reconstruction and analysis of the results using Matlab software 2009a. The principle of ECVT includes two stages of data collection capacitance of electrodes (forward problem) and image reconstruction from the measured capacitance (inverse problem). In the study, the simulation of image reconstruction was done by varying the object position, the number of objects and charge density of the object. From the simulation results showed that the reconstructed image with ILBP method is influenced by several parameters: the object's position in the sensor,charge density value of the object, an alpha value and the number of iterations was selected.</p>

Clock Scanning Microwave Interferometric Radiometer and Potential Application Analysis

Microwave (MW) radiometers at low-frequency bands play unreplaceable roles in Earth remote sensing, especially in the areas of numerical weather prediction (NWP) and climate research. All MW radiometers have been flown, so far, at low Earth orbit (LEO), which provide relatively narrow swath with long revisit time. There are increasing demands for applying MW radiometer at geostationary Earth orbit (GEO) for the purpose of having temporally continuous and spatially large coverage. Unfortunately, the required ground spatial resolution leads to a large-sized antenna that prevents MW radiometer applications, especially at low-frequency bands. The new concept of clock scanning microwave interferometric radiometer (CS-MIR) provides an opportunity to resolve this problem. By virtue of the simple and deployable array structure, it has the potential to work at GEO and produce hourly hemispheric imagery. This paper investigates the essential theory of CS-MIR and presents some approaches about its design principles in aspects of array configuration, sampling patterns, polarization corrections, and image reconstruction. The potential GEO applications of CS-MIR in frequencies lower than 50 GHz are investigated. Finally, a conceptual design of CS-MIR for SST measurement from GEO and the associated numerical simulations of image reconstruction are presented.

Airborne Downward Looking Sparse Linear Array 3-D SAR Heterogeneous Parallel Simulation

The airborne downward looking sparse linear array three dimensional synthetic aperture radar (DLSLA 3-D SAR) operates nadir observation with the along-track synthetic aperture formulated by platform movement and the cross-track synthetic aperture formulated by physical sparse linear array. Considering the lack of DLSLA 3-D SAR data in the current preliminary study stage, it is very important and essential to develop DLSLA 3-D SAR simulation (echo generation simulation and image reconstruction simulation, including point targets simulation and 3-D distributed scene simulation). In this paper, DLSLA 3-D SAR imaging geometry, the echo signal model and the heterogeneous parallel technique are discussed first. Then, heterogeneous parallel echo generation simulation with time domain correlation and the frequency domain correlation method is described. In the following, heterogeneous parallel image reconstruction simulation with two imaging algorithms, e.g., 3-D polar format algorithm, polar formatting and L1 regularization algorithm is discussed. Finally, the point targets and the 3-D distributed scene simulation are demonstrated to validate the effectiveness and performance of our proposed heterogeneous parallel simulation technique. The 3-D distributed scene employs airborne X-band DEM and P-band Circular SAR image of the same area as simulation scene input.

Image Reconstruction Based on Homotopy Perturbation Inversion Method for Electrical Impedance Tomography

The image reconstruction for electrical impedance tomography (EIT) mathematically is a typed nonlinear ill-posed inverse problem. In this paper, a novel iteration regularization scheme based on the homotopy perturbation technique, namely, homotopy perturbation inversion method, is applied to investigate the EIT image reconstruction problem. To verify the feasibility and effectiveness, simulations of image reconstruction have been performed in terms of considering different locations, sizes, and numbers of the inclusions, as well as robustness to data noise. Numerical results indicate that this method can overcome the numerical instability and is robust to data noise in the EIT image reconstruction. Moreover, compared with the classical Landweber iteration method, our approach improves the convergence rate. The results are promising.

Self‐calibration three‐dimensional light field display based on scalable multi‐LCDs

AbstractApproach to achieve self‐calibration three‐dimensional (3D) light field display is investigated in this paper. The proposed 3D light field display is constructed up on spliced multi‐LCDs, lens and diaphragm arrays, and directional diffuser. The light field imaging principle, hardware configuration, diffuser characteristic, and image reconstruction simulation are described and analyzed, respectively. Besides the light field imaging, a self‐calibration method is proposed to improve the imaging performance. An image sensor is deployed to capture calibration patterns projected onto and then reflected by the polymer dispersed liquid crystal film, which is attached to and shaped the diffuser. These calibration components are assembled with the display unit and can be switched between display mode and calibration mode. In the calibration mode, the imperfect imaging relations of optical components are captured and calibrated automatically. We demonstrate our design by implementing the prototype of proposed 3D light field display by using modified off‐the‐shelf products. The proposed approach successfully meets the requirement of real application on scalable configuration, fast calibration, large viewing angular range, and smooth motion parallax.

2-9 フレネルCGHの画像再生シミュレーションに関する考察(第2部門 自由視点・3次元画像)

2-9 フレネルCGHの画像再生シミュレーションに関する考察(第2部門 自由視点・3次元画像)

A new quantization method for SAR signals

AbstractWe propose a new quantization method for received synthetic aperture radar (SAR) signals and a quantizer design technique. This method divides the received signal into bandlimited signals by using orthogonal wavelet transforms and quantizes each bandlimited signal by a different quantizer. Employing this method, not only is there a reduction in the computational load for image reconstruction by the SAR fast approximate reconstruction proposed previously by the authors, but the accuracy of the reconstructed image is substantially improved when there are few quantization bits of the received signal, particularly in image reconstruction by the correlation method. In this paper, we design a quantizer for bandlimited signals and demonstrate the effectiveness of the proposed method by computer simulations of image reconstruction. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(9): 54–63, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10182

Method for correction of a two-dimensional image reconstructed from its projections

The reconstruction of a two-dimensional object by synthesis of its projections has been considered. The problem is solved with the aid of circular harmonic transforms. The formulas for tomographic reconstruction are obtained as expansions with respect to the systems of orthogonal functions outside the unit circle. These formulas are used for numerical simulation of image reconstruction.

Imagery in the Presence of Turbulence Using Slit Aperture Telescope With Partial Adaptive Corrections

The objective of this communication is to study and totest numerically the concept of partial adaptive correction with arotating Slit Aperture Telescope (SAT). After a brief summary of theprinciple of image reconstruction with the rotating SAT operating withoutthe atmospheric turbulence, we describe the simulations of imagereconstruction when a partial atmospheric correction is performed in onedimension only, along the long axis of the rotating SAT. Thereconstruction algorithm performs the inversion of the Radon transform.The SAT can use a small adaptive optics system with far fewer actuatorsthan conventional two-dimensional devices, but a relatively high degree ofone-dimensional correction is needed to recover a satisfactorytwo-dimensional image. The effect of additive noise on the reconstructedimage is also investigated.

A study on numerical simulation of image reconstruction in optical computer tomography

A study on numerical simulation of image reconstruction in optical computer tomography

Imaging speckle interferometer in space: image reconstruction by speckle masking

We propose the construction of a large multiple-mirror interferometer in space. For example, at λ ~ 100 nm and with a baseline of 20 m, a resolution of 0.001 sec of arc can be obtained. At short UV wavelengths a multiple-mirror interferometer will produce speckle interferograms caused by aberrations and deformations of the interferometer. From the speckle interferograms true diffraction-limited images can be reconstructed by various speckle methods. The speckle-masking method (triple correlation) is attractive since it yields true images with high signal-to-noise ratio. The limiting magnitude of interferometry in space is about 24. We will show digital simulations of image reconstruction from multiple-mirror interferometer data. Photon noise corresponding to a mean photon count number of 10 counts per pixel was simulated.

Detour phase error in the Lohmann hologram

An analysis of the errors present in the Lohmann hologram of a random phase image is undertaken. A Lohmann hologram in which the magnitude information and the phase information are modulated across the same direction is derived. This structure is used for detailed 1-D computer simulations of image reconstruction for Lohmann-type holograms. Qualitative and quantitative observations are made about the mean square error across the reconstructed image. These observations are then shown to compare well with theoretical predictions from a statistical error model.