Non-invasive estimation of the powder size distribution from a single speckle image

Non-invasive characterization of powders may take one of two approaches:imaging and counting individual particles;or relying on scattered light to estimate the particle size distribution(PSD)of the ensemble.The former approach runs into practical difficulties,as the system must conform to the working distance and other restrictions of the imaging optics.The latter approach requires an inverse map from the speckle autocorrelation to the particle sizes.The principle relies on the pupil function determining the basic sidelobe shape,whereas the particle size spread modulates the sidelobe intensity.We recently showed that it is feasible to invert the speckle autocorrelation and obtain the PSD using a neural network,trained efficiently through a physics-informed semi-generative approach.In this work,we eliminate one of the most time-consuming steps of our previous method by engineering the pupil function.By judiciously blocking portions of the pupil,we sacrifice some photons but in return we achieve much enhanced sidelobes and,hence,higher sensitivity to the change of the size distribution.The result is a 60×reduction in total acquisition and processing time,or 0.25 seconds per frame in our implementation.Almost real-time operation in our system is not only more appealing toward rapid industrial adoption,it also paves the way for quantitative characterization of complex spatial or temporal dynamics in drying,blending,and other chemical and pharmaceutical manufacturing processes.

Laser speckle contrast imaging to predict the effect of temporary spinal cord stimulation in postherpetic neuralgia patients: A prospective observational study

Temporary spinal cord stimulation(tSCS)can effectively reduce the pain and severity of postherpetic neuralgia(PHN).However,there are no effective and objective methods for predicting the effects of tSCS on PHN.Laser speckle contrast imaging(LSCI)is frequently used in neurology to evaluate the effectiveness of treatment.To assess the accuracy of LSCI in predicting the impact of tSCS on PHN,14 adult patients receiving tSCS treatments for spinal nerve-innervated(C6-T2)PHN participated in this observational study.Visual analog scale(VAS)assessments and LSCI bloodflow images of the-ngers were recorded after the tSCS procedure.The results showed that the VAS scores of all patients decreased signi-cantly.Moreover,the bloodflow index(BFI)values were signi-cantly higher than they were before the procedure.Increased bloodflow and pain alleviation were positively correlated.The-ndings indicated that spinal nerve PHN(C6-T2)was signi-cantly reduced by tSCS.Pain alleviation by tSCS was positively correlated with increased bloodflow in the hand.The effect of tSCS on PHN may thus be predicted using an independent and consistent indicator such as LSCI.

Application of three-dimensional speckle tracking technique in measuring left ventricular myocardial function in patients with diabetes

BACKGROUND Diabetic cardiomyopathy is considered as a chronic complication of diabetes mellitus(DM).Therefore,early detection of left ventricular systolic function(LVSF)damage in DM is essential.AIM To explore the use of the three-dimensional speckle tracking technique(3D-STI)for measuring LVSF in DM patients via meta-analysis.METHODS The electronic databases were retrieved from the initial accessible time to 29 April 2023.The current study involved 9 studies,including 970 subjects.We carried out this meta-analysis to estimate myocardial function in DM compared with controls according to myocardial strain attained by 3D-STI.RESULTS Night articles including 970 subjects were included.No significant difference was detected in the left ventricular ejection fraction between the control and the diabetic group(P>0.05),while differences in global longitudinal strain,global circumferential strain,global radial strain,and global area strain were markedly different between the controls and DM patients(all P<0.05).CONCLUSION The 3D-STI could be applied to accurately measure early LVSF damage in patients with DM.

Speckle structured illumination endoscopy with enhanced resolution at wide field of view and depth of field

Structured illumination microscopy(SIM)is one of the most widely applied wide field super resolution imaging techniques with high temporal resolution and low phototoxicity.The spatial resolution of SIM is typically limited to two times of the diffraction limit and the depth of field is small.In this work,we propose and experimentally demonstrate a low cost,easy to implement,novel technique called speckle structured illumination endoscopy(SSIE)to enhance the resolution of a wide field endoscope with large depth of field.Here,speckle patterns are used to excite objects on the sample which is then followed by a blind-SIM algorithm for super resolution image reconstruction.Our approach is insensitive to the 3D morphology of the specimen,or the deformation of illuminations used.It greatly simplifies the experimental setup as there are no calibration protocols and no stringent control of illumination patterns nor focusing optics.We demonstrate that the SSIE can enhance the resolution 2–4.5 times that of a standard white light endoscopic(WLE)system.The SSIE presents a unique route to super resolution in endoscopic imaging at wide field of view and depth of field,which might be beneficial to the practice of clinical endoscopy.

High performance“non-local”generic face reconstruction model using the lightweight Speckle-Transformer(SpT)UNet

Significant progress has been made in computational imaging(CI),in which deep convolutional neural networks(CNNs)have demonstrated that sparse speckle patterns can be reconstructed.However,due to the limited“local”kernel size of the convolutional operator,for the spatially dense patterns,such as the generic face images,the performance of CNNs is limited.Here,we propose a“non-local”model,termed the Speckle-Transformer(SpT)UNet,for speckle feature extraction of generic face images.It is worth noting that the lightweight SpT UNet reveals a high efficiency and strong comparative performance with Pearson Correlation Coefficient(PCC),and structural similarity measure(SSIM)exceeding 0.989,and 0.950,respectively.

Transmissive multifocal laser speckle contrast imaging through thick tissue

Laser speckle contrast imaging(LSCI)is a powerful tool for monitoring blood flow changes in tissue or vessels in vivo,but its applications are limited by shallow penetration depth under reflective imaging configuration.The traditional LSCI setup has been used in transmissive imaging for depth extension up to 2l_(t)–3l_(t)(l_(t)is the transport mean free path),but the blood flow estimation is biased due to the depth uncertainty in large depth of field(DOF)images.In this study,we propose a transmissive multifocal LSCI for depth-resolved blood flow in thick tissue,further extending the transmissive LSCI for tissue thickness up to 12lt.The limited-DOF imaging system is applied to the multifocal acquisition,and the depth of the vessel is estimated using a robust visibility parameter V_(r)in the coherent domain.The accuracy and linearity of depth estimation are tested by Monte Carlo simulations.Based on the proposed method,the model of contrast analysis resolving the depth information is established and verified in a phantom experiment.We demonstrated its effectiveness in acquiring depth-resolved vessel structures and flow dynamics in in vivo imaging of chick embryos.

A speckle noise suppression method based on surface waves investigation and monitoring data

The internal energy distribution of waves can be described using ocean-wave spectra.In many ways,obtaining wave spectra on a global scale is critical.Surface waves investigation and monitoring onboard the Chinese-French oceanography satellite is the first space-borne instrument for detecting wave spectra specially,which was launched on October 29,2018.It can avoid the shortage of synthetic aperture radar detection results while still having some problems,especially with the effects of speckle noise.In this study,a method to suppress the speckle noise is proposed.First,the empirical formula for background speckle noise is established.Second,many spatio-temporal representative fluctuation spectra are classified and averaged.Third,rational transfer function filtering is used to obtain speckle noise close to the along-track direction.Finally,a signal-to-noise ratio threshold is used to suppress the abnormal speckle noise.This method solves the problems existing in previous denoising methods,such as excessive denoising in the along-track direction and the inability of some abnormal noises to be denoised in the two-dimensional directional wave spectra.

Generation of high intensity speckles in overlapping laser beams

A new mechanism for the generation of high intensity speckles by coupling of overlapping beams is discovered and studied in detail.Using three-dimensional simulations,the coupling of overlapping beams smoothed by phase plates and by polarization smoothing are investigated in the regime relevant to inertial confinement fusion studies.It is found that the intensity distribution of the laser beam spot can be changed by nonuniform spatial phase modulation,and the speckles formed by the phase plate can be split into smaller speckles with higher intensities,which is favorable for the generation of laser plasma instabilities.Stimulated Brillouin scattering is compared in simulations with and without coupling of the overlapping incident beams,and the results confirm the enhancement of stimulated Brillouin scattering due to this mechanism.

Speckle Noise Suppression in Ultrasound Images Using Modular Neural Networks

In spite of the advancement in computerized imaging,many image modalities produce images with commotion influencing both the visual quality and upsetting quantitative image analysis.In this way,the research in the zone of image denoising is very dynamic.Among an extraordinary assortment of image restoration and denoising techniques the neural network system-based noise sup-pression is a basic and productive methodology.In this paper,Bilateral Filter(BF)based Modular Neural Networks(MNN)has been utilized for speckle noise sup-pression in the ultrasound image.Initial step the BFfilter is used tofilter the input image.From the output of BF,statistical features such as mean,standard devia-tion,median and kurtosis have been extracted and these features are used to train the MNN.Then,thefiltered images from the BF are again denoised using MNN.The ultrasound dataset from the Kaggle site is used for the training and testing process.The simulation outcomes demonstrate that the BF-MNNfiltering method performs better for the multiplicative noise concealment in UltraSound(US)images.From the simulation results,it has been observed that BF-MNN performs better than the existing techniques in terms of peak signal to noise ratio(34.89),Structural Similarity Index(0.89)and Edge Preservation Index(0.67).

In-flight deformation measurement for high-aspect-ratio wing based on 3D speckle correlation

In order to get an effective solution of the in-flight wing deformation measurement for high-wing aircrafts with high-aspect-ratio,a method based on three-dimensional(3D)speckle correlation technique is proposed.Firstly,an in-flight wing deformation measurement system with two sets of conjugate cameras is designed based on structural characteristics and test requirements of high-wing aircrafts with large-aspect-ratio.Secondly,the in-flight wing deformation measurement method based on 3D speckle correlation technique is introduced including three aspects:measuring system and wing datum calibration,speckle image matching and 3D reconstruction,and wing deformation analysis.Fi-nally,ground simulation test of dynamic deformation measurement of a scaled model wing and flight test of dynamic deformation measurement of a large transport wing are carried out.The test results show that the measuring accuracy of single point coordinate in ground simulation test is better than 0.1 mm/m,in the airborne vibration environment,the static single-point positioning accuracy is bet-ter than 5 mm,and the in-flight wing deformation measurement data is well received by the flight test engineers.This method can satisfy the requirements of stability,reliability,high precision,non-con-tact and full-field measurement for dynamic deformation measurement of aircraft wing with high-as-pect-ratio.

Numerical model for evaluating the speckle activity and characteristics of bone tissue under the biospeckle laser system

This paper discusses and studies the composition and characteristics of biospeckle on the surface of bone tissues.We used a laser speckle device to capture biospeckle patterns from fresh pig bone tissue.Traditional speckle activity metrics were used to measure the speckle activity of ex vivo bone tissue over time.Both Gaussian and Lorentzian correlation functions were used to char-acterize the ordered and disordered motion of the bone surface,together with volume scattering,to construct the model.Using the established mathematical model of the spatio-temporal evo-lution of the biospeckle pattern,it is possible to account for the presence of volume scattering from the biospeckle of bones,quantify the ordered or disordered motions in the biological speckle activity at the current time,and assess the ability of laser speckle correlation technique to determine biological activity.

LASER SPECKLE MOVEMENT CAUSED BY SURFACE DEFORMATION AND LIGHT WAVELENGTH CHANGE

When a surface is illuminated by laser,the field of diffusing reflective light can be described by Fresnel-Kirchhoff integration in the region of Fresnel.If the correlation,before and after the change of intensity field,is analysed by statistical method,three governing equations for variations of intensity field and speckle movement formulas can be obtained.In these equations,the surface motion,deformation and wavelength change are all considered to cause the speckle movement.

海洋SAR图像小波Speckle滤波及边缘信息提取

以海洋SAR图像的speckle滤波和边缘信息提取为研究目标 ,构造了以低通带通窄和时域冲击响应系数分布呈左右对称为特征的小波滤波器。这些特征使该小波滤波器在处理突变信号方面具有优良的特性。应用该小波滤波器 ,采用Wiener滤波算法 ,对海洋SAR图像进行了speckle滤波及采用Prewitt算子对边缘信息进行提取。用几种经典小波基函数采用相同的滤波算法和边缘增强算子进行了处理 ,并将它们的结果进行了对比分析。结果表明 ,虽然小波基函数在用于speckle滤波方面 ,稍逊其它几种经典小波基函数 ,但是在边缘信息保留方面 ,效果要明显优于其他小波基函数。

小波软阈值算法去除SAR图像中的Speckle噪声

在详细分析了Donoho小波软阈值的基础上 ,应用小波变换技术对SAR图像进行分析处理 .使用“小波局部软阈值算法”来计算阈值 ,对高频小波系数进行阈值确定 .求得估计小波系数 ,对其取小波反变换后 ,去除SAR图像中的Speckle噪声 .实验结果表明此方法对去除Speckle噪声十分有效 。

一种基于相对标准差的SAR图像Speckle滤波方法

通过分析SAR影像的Speckle局部统计特性和现有的空间滤波算法 ,提出了一种新的Speckle滤波方法 ,该方法以局部相对标准差为主要依据 ,采用特殊的滤波窗口邻域划分方法 ,自适应地调整窗口尺寸和窗口内的滤波区域。该方法被用于多幅ERS 1/ 2SAR图像去Speckle处理 ,并与以往的典型算法进行了比较实验 ,取得了令人满意的结果。

基于非线性加权均值的多方向广义形态滤波算法的Speckle噪声抑制

本文提出了一种新的用于散斑噪声抑制的非线性加权均值多方向广义形态滤波算法。对实际激光雷达图像处理结果表明:本文算法具备了小波阈值算法图像边缘保持好和局部统计滤波算法散斑噪声抑制能力强的优点,在算法复杂度降低的前提下具有了与F.Safa的改进算法(广义并行加权多方向形态滤波算法)相当的效果,即有效地抑制了散斑噪声,又保持了图像的几何结构。

基于CxImage库的SAR图像Speckle噪声抑制

合成孔径雷达图像的相干斑噪声抑制是SAR信息处理中的一个重要环节。经典的Speckle噪声抑制通常作为一个处理模块集成在软件中,但现有软件代码封装无法二次开发。针对文中提出了一种基于开源图像库CxImage的空间域自适应Speckle噪声抑制算法的应用与集成。将CxImage图像库链接入MFC应用程序框架中,利用其图像管理、维护、处理功能对SAR图像进行维护管理,集成多种经典的空间域自适应滤波方法,并以ERS-2卫星的PRISAR数据为例,进行Speckle噪声滤波处理,选取适当的滤波效果评价参数,对滤波结果进行比较,最终得出各滤波算法应用于SAR图像滤波的优劣。

Laser speckle contrast imaging for monitoring of acutepancreatitis at ischemia-reperfusion injury of thepancreas in rats

The influence of ischemia-reperfusion(I/R)action on pancreatic blood flow(PBF)and the development of acute pancreatitis(AP)in laboratory rats is evaluated in vivo by using the laser speckle contrast imaging(LSCI).Additionally,the optical properties in norm and under condition of AP in rats were assessed using a modied integrating sphere spectrometer and inverse Monte Carlo(IMC)software.The results of the experimental study of microcirculation of the pancreas in 82 rats in the ischemic model are presented.The data obtained conrm the fact that local ischemia and changes in the blood°ow velocity of the main vessels cause and provoke acute pancreatitis.

Ultrasound Speckle Reduction Based on Histogram Curve Matching and Region Growing

The quality of ultrasound scanning images is usually damaged by speckle noise.This paper proposes a method based on local statistics extracted from a histogram to reduce ultrasound speckle through a region growing algorithm.Unlike single statistical moment-based speckle reduction algorithms,this method adaptively smooths the speckle regions while preserving the margin and tissue structure to achieve high detectability.The criterion of a speckle region is defined by the similarity value obtained by matching the histogram of the current processing window and the reference window derived from the speckle region in advance.Then,according to the similarity value and tissue characteristics,the entire image is divided into several levels of speckle-content regions,and adaptive smoothing is performed based on these classification characteristics and the corresponding window size determined by the proposed region growing technique.Tests conducted from phantoms and in vivo images have shown very promising results after a quantitative and qualitative comparison with existing work.

Speckle噪声滤波算法的研究与设计

针对Speckle噪声的复杂性和真值图像的不可知性,结合奇异值分解和曲面拟合进行了消噪算法的研究与设计.首先对局部图像的奇异值分解结果采用中值滤波进行消噪,其次引入参数修正过程以替代传统的阈值处理方法,最后利用曲面拟合技术恢复局部图像并获得消噪结果.实验表明,与传统的滤波方法相比,从定性和定量方面进行分析,文中算法对Speckle噪声获得了较为满意的结果.