Zoom Factor Research Articles

Scalable and Isotropic Expansion of Tissues with Simply Tunable Expansion Ratio.

Tissue expansion techniques physically expand swellable gel‐embedded biological specimens to overcome the resolution limit of light microscopy. As the benefits of expansion come at the expense of signal concentration, imaging volume and time, and mechanical integrity of the sample, the optimal expansion ratio may widely differ depending on the experiment. However, existing expansion methods offer only fixed expansion ratios that cannot be easily adjusted to balance the gain and loss associated with expansion. Here, a hydrogel conversion‐based expansion method is presented, that enables easy adjustment of the expansion ratio for individual needs, simply by changing the duration of a heating step. This method, termed ZOOM, isotropically expands samples up to eightfold in a single expansion process. ZOOM preserves biomolecules for post‐processing labelings and supports multi‐round expansion for the imaging of a single sample at multiple zoom factors. ZOOM can be flexibly and scalably applied to nanoscale imaging of diverse samples, ranging from cultured cells to thick tissues, as well as bacteria, exoskeletal Caenorhabditis elegans, and human brain samples.

Method of paraxial design of rifle scope with four-element image-erecting zoom system and high zoom factor.

An analysis and a description of methods for a paraxial design of rifle scopes with a four-element image-erecting zoom system is performed. It is described a method of the calculation of basic design parameters of the rifle scope with the four-element image-erecting zoom system, where two inner elements are movable for ensuring zooming of the rifle scope. The method is demonstrated on two examples of the rifle scope design with the zoom factor 10×. Moreover, the possibility to design the rifle scope with the fixed position of the exit pupil using the four-element image-erecting zoom system with three movable elements is analyzed. The method of the initial paraxial design is demonstrated on two examples of the calculation of the basic rifle scope design parameters. The calculated parameters from proposed methods can be used in the aberration analysis and the optimization of the rifle scope parameters in optical design software.

Zoom into picometer: a picoscale equivalent phase-difference-generating method for testing heterodyne interferometers without ultraprecision stages

A simple and low-budget method aiming to generate phase difference equivalent to picoscale-measured displacements of heterodyne interferometers is proposed. By changing the length of an interference arm in an interferometer-like optical configuration, a small phase difference between the two wavelengths is generated for creating the same effect as a picoscale-measured displacement of the heterodyne interferometer. It is derived and experimentally demonstrated that the zoom factor, defined as the ratio of displacements in a heterodyne interferometer and the proposed method leading to the same phase difference, is proportional to the beat frequency and generally in a scale of 10 − 9. Thus, instead of ultraprecision piezo-stages, only a commercial linear guide rail is equipped in the method, and rigorous vibrating isolation is not necessary. The method has been already used to evaluate signal-processing electronics of a heterodyne grating interferometer.

Optimization of a Deep-Learning Method Based on the Classification of Images Generated by Parameterized Deep Snap a Novel Molecular-Image-Input Technique for Quantitative Structure-Activity Relationship (QSAR) Analysis.

Numerous chemical compounds are distributed around the world and may affect the homeostasis of the endocrine system by disrupting the normal functions of hormone receptors. Although the risks associated with these compounds have been evaluated by acute toxicity testing in mammalian models, the chronic toxicity of many chemicals remains due to high cost of the compounds and the testing, etc. However, computational approaches may be promising alternatives and reduce these evaluations. Recently, deep learning (DL) has been shown to be promising prediction models with high accuracy for recognition of images, speech, signals, and videos since it greatly benefits from large datasets. Recently, a novel DL-based technique called DeepSnap was developed to conduct QSAR analysis using three-dimensional images of chemical structures. It can be used to predict the potential toxicity of many different chemicals to various receptors without extraction of descriptors. DeepSnap has been shown to have a very high capacity in tests using Tox21 quantitative qHTP datasets. Numerous parameters must be adjusted to use the DeepSnap method but they have not been optimized. In this study, the effects of these parameters on the performance of the DL prediction model were evaluated in terms of the loss in validation as an indicator for evaluating the performance of the DL using the toxicity information in the Tox21 qHTP database. The relations of the parameters of DeepSnap such as (1) number of molecules per SDF split into (2) zoom factor percentage, (3) atom size for van der waals percentage, (4) bond radius, (5) minimum bond distance, and (6) bond tolerance, with the validation loss following quadratic function curves, which suggests that optimal thresholds exist to attain the best performance with these prediction models. Using the parameter values set with the best performance, the prediction model of chemical compounds for CAR agonist was built using 64 images, at 105° angle, with AUC of 0.791. Thus, based on these parameters, the proposed DeepSnap-DL approach will be highly reliable and beneficial to establish models to assess the risk associated with various chemicals.

Strategies for Optimizing the Determination of Second-Order Nonlinear Susceptibility Tensor Coefficients for Collagen in Histological Samples

Quantitative second harmonic generation microscopy methods that provide an estimate for the molecular structure of collagen in tissues by fitting theoretical models with experimental data at pixel-level are gaining increasing momentum. Such methods offer reliable diagnostic-relevant information that complement traditional histology procedures. We provide guidelines on selecting the optimal experimental data acquisition parameters (frame or pixel averaging, pixel dwell time, pixel size, zoom factor) and the most suited pre-processing steps (thresholding, averaging of pixels) for ensuring experimental data fitting with very high performance. Under controlled image acquisition conditions, we also propose pixel fitting efficiency calculation which varies across distinct tissue types and has potential to be used to differentiate tissues exhibiting distinct collagen architectures.

Zoom based image super-resolution using DCT with LBP as characteristic model

The prime intention of super-resolution (SR) technique is to restore the high-resolution images from one or more low-resolution (LR) images. These images are captured from the same scene with different acquisition systems with different resolution. Because these acquisition systems, images are suffered for an ill-posed problem with low visualization and picture information. Therefore, in this paper, the zoom-based super-resolution approach is proposed for super-resolution of low resolute images which are acquired from different camera zoom-lens. In this approach, three LR images of the same static scene which are acquired using three distinct zoom factors are used. Learning-based SR technique is used to enhance the spatial resolution of these LR images. The training dataset comprises three sets of captured images which are LR images, an enhanced version of LR images-HR1 and enhanced version of HR1 images-HR2. High-frequency details of the super-resolute image are learned in form of the discrete cosine transform (DCT) coefficients of HR training images. Finally, the super-resolved versions of LR observations, captured at different zoom-factors, are combined. The experimental results show that this proposed approach can be applied to various types of natural images in grayscale as well as color. The experimental results also show that this proposed approach performs better than existing approaches.

Accuracy assessment technique for testing multiple sub-pixel mapping downscaling factors

ABSTRACTSub-pixel mapping (SPM; a.k.a. super-resolution mapping) is a sub-field of remote sensing focused on mapping the spatial distribution of land covers from fractional land cover maps, such as those produced by spectral unmixing. A necessary consideration for developing universally applicable SPM methods is that they are able to function across multiple target scales (i.e. zoom factors). Yet most studies test only a single scale, likely due to the challenges of testing a SPM technique that is transferable across multiple scales. This study develops a simple adjustment to the widely used confusion-error matrix that can account for the uncertainties introduced when reference data must be aggregated to permit testing multiple downscaling factors. Results show how off-diagonal components (e.g. errors of commission and omission) can be adjusted to account for the overestimation of disagreement that occurs during scale translations. Furthermore, results show how supplemental accuracy can be accounted for between the SPM result and areas with low fractional proportions, which is not possible using currently available methods. This simple yet effective way to compare accuracies across scale factors provides a means to develop and test SPM methods applicable across multiple scales.

Performance Evaluation of a Dedicated Preclinical PET/CT System for the Assessment of Mineralization Process in a Mouse Model of Atherosclerosis.

The purpose of this study was to assess the impact of positron emission tomography/X-ray computed tomography (PET/CT) acquisition and reconstruction parameters on the assessment of mineralization process in a mouse model of atherosclerosis. All experiments were performed on a dedicated preclinical PET/CT system. CT was evaluated using five acquisition configurations using both a tungsten wire phantom for in-plane resolution assessment and a bar pattern phantom for cross-plane resolution. Furthermore, the radiation dose of these acquisition configurations was calculated. The PET system was assessed using longitudinal line sources to determine the optimal reconstruction parameters by measuring central resolution and its coefficient of variation. An in vivo PET study was performed using uremic ApoE-/-, non-uremic ApoE-/-, and control mice to evaluate optimal PET reconstruction parameters for the detection of sodium [18F]fluoride (Na[18F]F) aortic uptake and for quantitative measurement of Na[18F]F bone influx (Ki) with a Patlak analysis. For CT, the use of 1 × 1 and 2 × 2 binning detector mode increased both in-plane and cross-plane resolution. However, resolution improvement (163 to 62μm for in-plane resolution) was associated with an important radiation dose increase (1.67 to 32.78Gy). With PET, 3D-ordered subset expectation maximization (3D-OSEM) algorithm increased the central resolution compared to filtered back projection (1.42 ± 0.35mm vs. 1.91 ± 0.08, p < 0.001). The use of 3D-OSEM with eight iterations and a zoom factor 2 yielded optimal PET resolution for preclinical study (FWHM = 0.98mm). These PET reconstruction parameters allowed the detection of Na[18F]F aortic uptake in 3/14 ApoE-/- mice and demonstrated a decreased Ki in uremic ApoE-/- compared to non-uremic ApoE-/- and control mice (p < 0.006). Optimizing reconstruction parameters significantly impacted on the assessment of mineralization process in a preclinical model of accelerated atherosclerosis using Na[18F]F PET. In addition, improving the CT resolution was associated with a dramatic radiation dose increase.

Count of main pest of Oil-Bearing (Rosa damascena Miller)’s Rose Soft Scale (Rhodococcus perornatus Cockerell &amp; Parrott) by using image processing methods

Harmful counting of oil roses is&#x0D; carried out by agricultural experts using direct counting method (under&#x0D; stereomicroscope, generally 40X Zoom). But frequent influences from human&#x0D; situations such as fatigue, boredom and carelessness cause counting errors. The&#x0D; method of outputting the project differs because it is a method which has not&#x0D; been applied in this field before and because error rate is not reduced to&#x0D; zero. Dish samples taken from the oil roses grown in Isparta central region&#x0D; were separated into 1.5 cm pieces and prepared for measurement. 13 sample&#x0D; branch images were taken by Leica brand Z16 APO model macroscope (1X&#x0D; Magnification); (0.57 Zoom factor); (16: 1 Zoom) scaled. Acquired images were&#x0D; processed in the Leica las 4.50 microscope software platform by performing the&#x0D; necessary image quality enhancement operations. Images from the macroscope are&#x0D; converted into countable form by Matlab program and software language using&#x0D; morphological image processing methods. An algorithm has been created to determination&#x0D; of the 2.nimf adults cochineal, 1.nimf cochineal and 2.nimf cochineal and&#x0D; calculate average cochineal dimensions. Counting was done and schedules were&#x0D; arranged according to the written algorithm.

Pelvic Meckel's Diverticulum Mimicking Bladder on Meckel Scan; The Impact of Quality Control and Technical Issues.

Quality control and technical issues are essential for high-quality imaging. An important technical parameter of image acquisition is selecting zoom factor according to camera field-of-view dimensions and patient's body size. Here, we present a case of atypically located Meckel's diverticulum mimicking bladder on Meckel scan.

Adaptive cubature Kalman filtering for distant speech tracking using a circular microphone array

A joint processing framework for distant speech tracking is proposed based on combination of an adaptive cubature Kalman Filter with a 80-element circular microphone array. The deconvolved convention beamforming (DCB) [T. C. Yang, 10.1109/JOE.2017.2680818] is carried out over the distant speech data for speech enhancement and bearing estimate. DCB provides superdirective beams and offers the same robustness as conventional beamforming. With the estimated speech bearing, a “current” statistical (CS) motion model is combined with a cubature Kalman filter to track the speech of interest. The CS model assumes a modified Rayleigh distribution for the acceleration probability density (of the moving source) whose mean value is the current acceleration. Based on this model, we utilize a zoom factor achieved by computing the norm of the tracking innovation to adjust the dynamic state model adaptively. Both numerical simulation and the outdoor experimental results show that the proposed framework in this paper can effectively track a maneuvering speech source.

Realistic Film Grain Rendering

Film grain is the unique texture which results from the silver halide based analog photographic process. Film emulsions are made up of microscopic photo-sensitive silver grains, and the fluctuating density of these grains leads to what is known as film grain. This texture is valued by photographers and film directors for its artistic value. We present two implementations of a film grain rendering algorithm based on a physically realistic film grain model. The rendering algorithm uses a Monte Carlo simulation to determine the value of each output rendered pixel. A significant advantage of using this model is that the images can be rendered at any resolution, so that arbitrary zoom factors are possible, even to the point where the individual grains can be observed. We provide a method to choose the best implementation automatically, with respect to execution time. The C++ code for this work is available, as well as an online demo http://dev.ipol.im/~nfaraj/ipol_demo/film_grain/.

A Stochastic Film Grain Model for Resolution‐Independent Rendering

AbstractThe realistic synthesis and rendering of film grain is a crucial goal for many amateur and professional photographers and film‐makers whose artistic works require the authentic feel of analogue photography. The objective of this work is to propose an algorithm that reproduces the visual aspect of film grain texture on any digital image. Previous approaches to this problem either propose unrealistic models or simply blend scanned images of film grain with the digital image, in which case the result is inevitably limited by the quality and resolution of the initial scan. In this work, we introduce a stochastic model to approximate the physical reality of film grain, and propose a resolution‐free rendering algorithm to simulate realistic film grain for any digital input image. By varying the parameters of this model, we can achieve a wide range of grain types. We demonstrate this by comparing our results with film grain examples from dedicated software, and show that our rendering results closely resemble these real film emulsions. In addition to realistic grain rendering, our resolution‐free algorithm allows for any desired zoom factor, even down to the scale of the microscopic grains themselves.

Task-Based Modeling of a 5k Ultra-High-Resolution Medical Imaging System for Digital Breast Tomosynthesis.

High-resolution, low-noise X-ray detectors based on CMOS active pixel sensor (APS) technology have demonstrated superior imaging performance for digital breast tomosynthesis (DBT). This paper presents a task-based model for a high-resolution medical imaging system to evaluate its ability to detect simulated microcalcifications and masses as lesions for breast cancer. A 3-D cascaded system analysis for a 50- [Formula: see text] pixel pitch CMOS APS X-ray detector was integrated with an object task function, a medical imaging display model, and the human eye contrast sensitivity function to calculate the detectability index and area under the ROC curve (AUC). It was demonstrated that the display pixel pitch and zoom factor should be optimized to improve the AUC for detecting small microcalcifications. In addition, detector electronic noise of smaller than 300 e- and a high display maximum luminance (>1000 cd/cm 2) are desirable to distinguish microcalcifications of [Formula: see text] in size. For low contrast mass detection, a medical imaging display with a minimum of 12-bit gray levels is recommended to realize accurate luminance levels. A wide projection angle range of greater than ±30° in combination with the image gray level magnification could improve the mass detectability especially when the anatomical background noise is high. On the other hand, a narrower projection angle range below ±20° can improve the small, high contrast object detection. Due to the low mass contrast and luminance, the ambient luminance should be controlled below 5 cd/ [Formula: see text]. Task-based modeling provides important firsthand imaging performance of the high-resolution CMOS-based medical imaging system that is still at early stage development for DBT. The modeling results could guide the prototype design and clinical studies in the future.

Three-minute SPECT/CT is sufficient for the assessment of bone metastasis as add-on to planar bone scintigraphy: prospective head-to-head comparison to 11-min SPECT/CT

BackgroundThe aim of this study is to assess whether ultra-fast acquisition SPECT/CT (UF-SPECT/CT) can replace standard SPECT/CT (std-SPECT/CT) as “add-on” to whole-body bone scintigraphy (WB-BS) for the investigation of bone metastases.Consecutive cancer patients referred for WB-BS who underwent SPECT/CT in addition to WB-BS were included. Std-SPECT, UF-SPECT, and low-dose CT were performed (std-SPECT: matrix 128 × 128, zoom factor 1, 20 s/view, 32 views; UF-SPECT: identical parameters except for 10 s/view and 16 views, reducing the acquisition time from 11 to 3 min). A consensus diagnosis was reached by two observers for each set of images (WB-BS + standard SPECT/CT or WB-BS + UF-SPECT/CT) using a three-category evaluation scale: M0: no bone metastases; M1: bone metastases; and Me: equivocal findings.ResultsAmong the 104 included patients, most presented with prostate cancer (n = 71) or breast cancer (n = 28). Using WB-BS + std-SPECT/CT, 71 (68%) patients were classified as M0, 19 (18%) as M1, and 14 (14%) as Me. Excellent agreement was observed between WB-BS + std-SPECT/CT and WB-BS + UF-SPECT/CT using the three-category scale: kappa = 0.91 (95% CI 0.84–0.97). No difference in observer agreement between cancer types was detected. SPECT/CT provided a definitive classification in 90 of 104 cases in which WB-BS was not entirely diagnostic.ConclusionsTo investigate potential bone metastases, UF-SPECT/CT can be conducted as add-on to WB-BS to notably reduce the SPECT acquisition time without compromising diagnostic confidence.

Image Noise Analysis of a Large Ring PET Scanner

Image noise analysis of a large ring PET scanner “macro PET” performed using two different phantoms, namely a Jaszczak SPECT phantom and a uniform cylindrical phantom. In the present work, simple 2D filtered back projection was used to reconstruct all the images, and in almost all the cases a Hamming filter of cutoff frequency 0.4 and a 256 by 256 matrix with zoom factors from 1 to 4 were used in order to investigate the imaging capabilities of the new scanner and the influence of filter and cut-off frequency on the filtered back projected images. Results indicate that 11.1 mm cold rod in the Jaszczak phantom images can consistently be seen. The Coefficient of variation (CV) results for Hann and Hamming filters are very similar and increase approximately in linear fashion with higher cutoff frequency. The value of CV for the Parsen filter is lower than the value for Hann and Hamming filters. It concludes that all filters with low cut off-frequency (0.6) would suppress image noise but decrease contrast.

Optics design for Electron Cyclotron Emission Imaging system on J-TEXT

An electron cyclotron emission imaging (ECEI) system is being developed for J-TEXT. It is comprised of two 16-channel antenna arrays that share the same toroidal window for the purpose of observing separate radial regions of the tokamak plasma simultaneously. Two imaging optic units have been designed, which share the same zoom lenses, but have different focus lenses. The setup is flexible and achieves good spatial resolution. In particular, the poloidal zoom factor can achieve 1.17 to 2.20. The desired focal plane can range anywhere from high field side (HFS) edge to low field side (LFS) edge. The effective field curvature adjustment (FCA) lenses have been adopted for the ECEI imaging optic system, which make the image plane flat enough to match the emission layer in order to increase the image quality.

Superresolution from a Single Noisy Image by the Median Filter Transform

The task of single-image superresolution is to obtain a high resolution image from a low resolution input. Many strategies have achieved considerable success by learning from image databases so as to find suitable replacements for the missing information. However, little effort has been devoted to coping with significant amounts of noise in the input. Noise makes the problem even harder, since its distribution is unknown in many practical cases. Here an approach is proposed to solve this problem irrespective of the noise type, which supports both integer and fractional zoom factors. It is based on the application of the median filter on parallelogram shaped windows chosen according to a suitable probability distribution. The resulting outputs are then median filtered again to obtain the final output. Experimental results are reported for artificial and natural images under Gaussian and impulsive uniform noise. It is found that the proposed approach outperforms several state-of-the-art single-image superre...

Unsteady camera zoom stabilization using slope estimation over interest warping vectors

Projections being based on global image representative are considered as simplified and efficient stabilization solutions under poor textural or imaging conditions. The existing projection algorithms are investigated only for translation or rotation stabilization, but the image captured with unsteady camera also suffers from undesired zoom-in/out effect. This paper presents a new zoom estimation algorithm for extended projection applicability. Camera focusing generally being effective around its optical axis, produces zooming around the image center. This image-centered zoom results in an opposite relative motion (stretching/compression) in two halves of the image projections. A novel concept of utilizing this relative longitudinal projection motion is proposed for camera zoom estimation. Derivative dynamic time warping is used for image projection alignment and the effect of mismatched-warping singularities leading to motion estimation error is removed by selecting some key warping vectors labeled as Interest Warping Vectors. Slope values of these interest warping vectors in the two projection-halves are utilized for zoom factor estimation and the approach is also generalized for arbitrary zoom-center under forward translation. Robustness of the proposed algorithm tested with artificial textural artifacts is verified with motion accuracy analysis on various sequentially zoomed test and real-world images within 0.8 to 1.2 scale factor range.

Class Allocation for Soft-Then-Hard Subpixel Mapping Algorithms With Adaptive Visiting Order of Classes

The soft-then-hard subpixel mapping (STHSPM) algorithm is a type of subpixel mapping (SPM) algorithm consisting of soft class value (between 0 and 1) estimation and hard class allocation for each subpixel. This letter presents a new class allocation method for STHSPM algorithm. As an extension of our previous work in which subpixels for classes are decided in units of classes (UOC), the new approach, named adaptive UOC (AUOC), improves UOC with adaptive visiting order of classes. In AUOC, the visiting order of classes within each coarse pixel is determined based on the local structure rather than the global structure in UOC. Experiments on three remote sensing images show that AUOC is able to improve UOC in terms of SPM accuracy, particularly for SPM with small zoom factors.