Moire Images Research Articles

Progressive Moire Removal and Texture Complementation for Image Demoireing

Taking photos of digital screens often produces color-distorting moire patterns caused by inconsistency between the color filter array of cameras and the sub-pixel layout of screens, which severely degrades the quality of photos. Most existing demoireing methods employ multi-stream network architecture to simultaneously process the same moire image with different resolutions, but they neglect the complementarity among different resolutions. In this paper, we propose a novel moire removal model to address this issue. Unlike the existing multi-stream based approaches, in this model, we present a progressive texture complementation block to exploit the complementary information from different resolutions in order to progressively remove moire textures and restore image content. Additionally, we propose a residual moire removal block, in which the depthwise separable convolution is utilized to remove moire from image while reducing computation overhead. This block also includes a local color correction structure, which is used to correct color shifts presented in the moire images. Experimental results on two public datasets show that our method outperforms state-of-the-art methods. Besides, the quantity of parameters and FLOPs of our model are tens of times fewer than the off-the-shelf models. Furthermore, our network framework can adapt well to another low-level vision task, rain removal, in which our model also achieves state-of-the-art performance.

Image Demoireing via U-Net for Detection of Display Defects

Mura defects, which occur during display manufacturing, degrade the quality of the display. Therefore, Mura detection is critical. When the camera is focused on the display for accurately detecting Mura defects, a moire pattern occurs in a captured image because of the frequency difference between the subpixels of the display and the color filter array of the camera. Typical image data handled with existing demoireing methods do not have Mura defects and include synthetic moire images. Therefore, we created a dataset to detect Mura defects that include real moire patterns, classified into two categories: weak and strong. We propose a new demoireing framework to remove the moire patterns in the captured image, thereby accurately detecting Mura defects. We also propose inserting ArUco markers for accurate alignment and automation, conducting multiple experiments with U-Net. Based on the captured data, the proposed U-Net, which combines a frequency loss and data augmentation, improves the performance by 6.41 dB higher for the weak moire pattern and 4.14dB higher for the strong moire pattern than state-of-the-art networks in terms of peak signal-to-noise ratio.

INVESTIGATING THE IMPACT OF AN EXTERNAL INFLUENCE ON THE DYNAMIC BEHAVIOR OF DISLOCATIONS IN SILICON CRYSTALS

The results of studying of the influence of a constant magnetic field on the dynamic behavior of dislocations in the crystalline block of an interferometer subsequently subjected to uniaxial mechanical tensile stress along the crystallographic axis of silicon are presented. The periodicity of the dilatation moire image after these influences, the average means free path of a dislocation in a crystal (block), the amount of slip, the average density of dislocations along the slip line, the relative deformation, and Young's modulus are calculated. To study the effect of a stable magnetic field on the dynamic behavior of dislocations in silicon crystals, a special three-block X-ray interferometer was fabricated in one of the blocks, and dislocations were introduced using the technique proposed by us. The experiments were carried out for various values of the magnetic field induction and mechanical stress. It is shown that the sequential action of these external influences leads to an increase in the starting stress, a decrease in the velocity of dislocation movement, a delay in the onset of dislocation movement, and the appearance of a hardening phenomenon. Experiments show that the displacement mobility characteristics are especially sensitive when the modulus of the magnetic induction vector reaches a certain threshold value for a given sample. It was shown that, in a sample containing silicon dislocations, the magnetic memory that appears after storage in a magnetic field is short-lived. It is found that the speed of movement of a dislocation in a magnetic field processed by a magnetic field, "then" subjected to mechanical stress (stretching), changes, but in practice the energy of its activation does not change. A theoretical analysis of the above experimental results is carried out, their scientific substantiation is given, all the factors associated with the phenomena observed in experiments are revealed.

Two-axes tilt sensing using circular gratings moiré

A circular grating moire method is proposed for sensing the tilt magnitude (θ) and tilt direction (α) for tilt about two orthogonal axes. A device consisting of a pair of fixed (upper) and semifloating (lower) circular gratings inside a water-filled acrylic container has been developed. The moire pattern images for tilt angles ranging from 0 deg to 7 deg are captured using a webcam, processed by low-pass filtering and transformed from Cartesian-to-polar coordinates. This is followed by column-wise fringe center localization using polynomial fitting, unwrapping of the extracted fringe centers, and sine-curve fitting. The peak-to-valley height (hpv) and phase shift (φ) of the unwrapped and fringe centers were determined from the fitted sine curve. The relationship between hpv and θ is found to be parabolic with the y-intercept at its minimum point, whereas that between φ and α is linear. From the tilt sensing experiments, the mean absolute errors in θ and α are found to be 0.16 deg and 3.1 deg, respectively, with uncertainty of ±0.027 deg and ±0.5 deg at 95% confidence level. The proposed device is capable of sensing tilt magnitude and direction along two orthogonal tilt planes and can potentially be applied in landslide monitoring.

Design of inspection system for exterior quality of steel plate

In this paper, in view of the on-line inspection of the thickness of steel plate and its surface defects, a quality inspection system for appearance of steel is designed. The moire image on the surface of the steel plate is collected by a linear CCD camera. The fringe image is transformed by wavelet transform, and the phase information of wavelet transform coefficients corresponding to the wavelet ridge is extracted to reconstruct the 3D profile. Experimental results show that the thickness measurement precision of the steel plate is 0.08 mm and the measurement accuracy of the surface defect is 0.2 mm. The online detection speed is 6 m/s. The on-line detection of thickness and surface defect of steel plate can be realized.

Measurement of Vertebral Rotation from Moire Image for Screening of Adolescent Idiopathic Scoliosis

Measurement of Vertebral Rotation from Moire Image for Screening of Adolescent Idiopathic Scoliosis

Implement of Digital Moire technique on DSP for alignment of partial compensation interferometer

Digital Moiré technique is adopted in partial compensation interferometer (PCI) for high-precision testing of figure error of the aspheric surfaces. The figure error of the measured aspheric is obtained by a series of calculation with the real interferogram and ideal interferograms generated by computer. The dense interference fringes at the exit pupil make it difficult to align the PCI. On the contrary, digital Moire fringes composed from real and ideal interferograms are sparse and corresponding to the figure error of the measured aspheric, making it easier to align the PCI. Generally, digital Moire technique is processed on the computer, resulting in slow processing speed and difficult display in real time. Digital Signal Processor (DSP) can be used to implement digital Moire technique and display digital Moire fringes in real time with its powerful processing capacity. In this paper, digital Moire technique is implemented on the TMS320C6455 DSP. The hardware system consists of a DSP module, a CCD camera and a monitor. Finally we experimentally obtain the digital Moire image, and further analyze how to align the PCI theoretically.

Reconstruction of planar periodic structures based on Fourier analysis of moiré patterns

In recent years, inverse moire methods have been developed to reconstruct micro/nano-scale planar periodic structures with a larger field of view than those constructed using conventional methods. In these methods, moire fringes generated by superposition of the periodic structure and a reference grating are analyzed to reconstruct the periodic structure. There are two approaches to inverse moire methods: the fringe-centerlines method and the phase-shifting method. The former has lower accuracy and is difficult to automate, while the latter requires at least three moire images with complicated processing. A reconstruction method for planar periodic structures using Fourier analysis is proposed. This method can be used to characterize the micro/nano periodic structure from a single microscope moire pattern. At the same time, when combined with a linewidth characterization method, the period and linewidth of the microstructure can be obtained simultaneously. As practical examples, the period and linewidth of a scanning electron microscopy raster are calibrated. Then the microstructures of a micro-electroformed grating and a butterfly wing are reconstructed using the calibrated system. The proposed method provides a tool for the characterization of large area micro/nano periodic structures. Further, this is a promising approach to detect defects in periodic structures.

Measurement of Distortion Using the Moire Interferometry

Image forming lens systemsdo not provide perfect images. Lens abberations can be detected with complex optical ray-tracing. A single aberration in lenses, the distortion, can be detected at the image plane with optical mapping. Therefore moire interferometry can be adapted to detect and measure distortion. This method is adaptable by serial testing of the universal measuring cameras, projection cameras, photogrammetrical cameras, etc. The distortion of the whole image plane can be represented on one moire image. This can be useful if the distortion is not rotationally symmetrical for example because of errors of assembly. The distortion of 1 µm regarding the focal plane can be measured by using the moire method presented in this paper.

AUTOMATIC DETECTION OF SPINAL DEFORMITY BASED ON STATISTICAL FEATURES FROM THE MOIRE TOPOGRAPHIC IMAGES

Spinal deformity is one of a disease mainly suffered by teenagers during their growth stage particularly from element school to middle school. There are many different causes of abnormal spinal curves, but all of them are unknown. To find the spinal deformity in early stage, orthopedists have traditionally performed on children a painless examination called a forward bending test in mass screening of school. But this test is neither objective nor reproductive, and the inspection takes much time when applied to medical examination in schools. To solve this problem, a moire method has been proposed which takes moire topographic images of human backs and checks symmetry/asymmetry of their moire patterns. In this paper, we propose a method for automatic judgment of spinal deformity which is obtained moire topographic images based on statistical features on the moire image. Statistical feature of asymmetry degrees are applied to train employing the classifier such as Artificial Neural Network, Support Vector Machine, Self-Organization Map and AdaBoost.

Processing of digital moiré images in Salus Ortopédtechnika Kft.

More and more children and youngsters are affected by spinal deformities these days. These diseases can be well cured if they are detected and filtered out in time. We wanted to set up an objective and safe method with which we can diagnose wide spectrum of school-aged youngsters without harmful side-effects. Creating moire images was one way to solve this problem, that is the reason why we started to test this method in filtering and following the condition of our young patients. Patients measured by us were going through a general examination method where their phisical status was examined by physiotherapists, and relief images were taken of their back. The initial aim to make the moire image use an objective method to filter and follow the patient’s condition in case of weed curvature of the spine could not be totally fulfilled. The reason is that the evaluation of the images is still a subjective method done by our vision. A possible solution could be to find an objective evaluation method where we can process, evaluate and compare the images with the same conditions. The programming and use of a proper image processing algorithm could be a great help for us. DOI: 10.17489/biohun/2013/1/16

Depth sensors in screening of scoliosis

The aim of the presented project was to develop equipment for screening and early recognizing of scoliosis. The Moire method is generally used in practice, but the correct processing of Moire images is not currently solved. Depth sensors capture images which describe the distances of the observed surfaces from the camera. With the help of these sensors a 2.5 D model of the human back can be created. This model can be used to create an automatic or semi-automatic scoliosis diagnosis system. The paper describes the development, structure and internal mechanisms of such a measurement method.

Optical axis alignment for three-aspherical mirrors system using five parallel laser beams and moiré method

In this paper, a new optical technique involving the five parallel laser beams alignment device and moire method was developed to rapidly and accurately align the optical axis of three-aspherical mirrors system (TAMS). In this method, the optical axis of a first aspherical mirror is made parallel to the “five incident parallel laser beams” in the plane of incidence. The height and orientation of the first aspherical mirror are fine tuned and the alignment is assured by examining the direction of these five reflected laser beams. The optical axes of second and third aspherical mirror are aligned by five parallel laser beams in accordance with the configuration parameter of optical system in sequence. The effective focal length (EFL) of the TAMS was measured by moire method and image formula. This novel method is used to align the optical axis of TAMS and the EFL deviation estimated has an accuracy of 1%.

モアレ風画像への別モアレ模様の合成法

モアレ風画像への別モアレ模様の合成法

バイラテラルフィルタによるモアレ風画像の生成

バイラテラルフィルタによるモアレ風画像の生成

モアレ風画像生成のためのバイラテラルフィルタのパラメータの検証

モアレ風画像生成のためのバイラテラルフィルタのパラメータの検証

Micro 3D measurement method using SEM

Three diamensional (3D) measurement method by Scanning Electron Microscope (SEM) has already been proposed by using the principle of shadow moire. In the method, the image of original grid in shadow moire image must be clearly removed in fringe analysis process in order to perform high resolution analysis. A new method based on the principle of projection moire is proposed to solve the trouble concerning the grid. In this paper, the mechanism of producing some shadows of grid on the surface of the object by back scattering electron beam in the new method is discussed. Fringe image as shadow of grid is analyzed by Wavelet transform. The precise 3D measurement is realized by using the phenomenon of shadows of grid. Furthermore, a 3D micro structure on the head of a hard disk is measured. From the comparison of results obtained by Atomic Force Microscope (AFM), it is confirmed that the proposed method has high-resolution power(about 20nm).

103 CCDカメラによるモアレ縞の検出及び評価(セッション1 画像応用・可視化)

Due to the interference between two sets of repetitive gratings Moire fringes are generated. These patterns are also used in metrology for the measurements of surface profilometry, 3D surface reconstruction and so on. Recently it is approached as an emerging tool in the fields of biomedical engineering fields - particularly in biomechanics and bio-sensing. Conventional Moire interferometry evaluates the interference of two light waves being reflected on a reference surface and the object to be profiled. However, difficulties in satisfying the requirements for the current significant issues in obtaining accurate dimensional information as well as dimensional deformation are dealing with micro-level and nano-level in an on-line inspection environment. Particularly, in the present real-time biomedical inspection of auto-inspection and auto-operation of inner organs of human body needs precise information of inner movements. In that case single light wave system makes the Moire sensing system easier and applicable in real-time imaging. However, modeling the sensing system based on CCD parameters of the camera and its application in capturing of Moire images make the systems challenging as well.

Origin of Moiré structures inC60on Pb(111) and their effect on molecular energy levels

Low-energy electron diffraction LEED indicates that the monolayer structure of C60 on Pb 111 comprises two coexisting incommensurate structures with nonsymmetry epitaxial rotations near 20° relative to the Pb 111 lattice. These structures are observed in scanning tunneling microscopy STM as Moire superstructures having periods of about 46 A and 34 A. The Moire images and LEED patterns are consistent with two higher-order commensurate HOC structures that were identified using the hexagonal number sequence method. These structures are close to predictions from the Novaco-McTague theory of epitaxial rotation, assuming a weakly corrugated substrate potential. As a consequence of the fullerenes within the Moire structures having different local environments, the energetic alignment of the molecular resonances is also modulated, with shifts measured by tunneling spectroscopy of up to 20 meV.

Development of Warpage Measurement System to Simulate Convective Solder Reflow Process

In this paper, a warpage measurement system to simulate forced convective reflow is discussed. A warpage measurement system that can simulate convective reflow enables the real-time monitoring of printed wiring boards (PWBs), PWB assemblies (PWBAs), and chip package warpage during the reflow process. This paper will describe the two major parts of the warpage measurement system: the optical measurement part which utilizes the projection Moire method and advanced image processing, as well as the laboratory oven which is used to simulate forced convective reflow. This is the first system that allows PWB/PWBA/chip package warpage to be measured during a simulated convective reflow process. Also, this is the first system that employs automatic image segmentation to separately extract the warpage of the PWB and electronic components from the same measurement. The results will show that when compared to infrared heating which was previously used in this research area, convective heating minimizes thermal gradients on the PWB/PWBA sample. Thermal gradients on the PWB/PWBA sample have the inadvertent effect of inducing warpage into the sample and will interfere with the warpage measurement result. In the first design iteration presented in this paper, the system can simulate low ramp rate industrial convective reflow profiles and simultaneously measure the warpage of PWBAs. A computational fluid dynamics (CFD) model of the system was developed to determine how to increase the system's heating rate. The CFD model was used to perform a design of simulations (DOS) and regression analysis. The validated regression results will be used to predict oven design parameters to enable the next iteration of the convective system to simulate high ramp rate convective reflow profiles. This paper will show that the presented system is a powerful tool for measuring the warpage of PWBs, PWBAs, and chip packages.