Moiré pattern

About: Moiré pattern is a research topic. Over the lifetime, 1917 publications have been published within this topic receiving 27176 citations. The topic is also known as: moiré fringes & moire pattern.

Color halftone document segmentation and descreening

Abstract: The advent of electronic publishing creates strong interest in converting existing printed documents into electronic formats. During this process, image reproduction problems can occur due to the formation of moire patterns in the screened halftone areas. A wavelet packet based color halftone segmentation algorithm is first designed to locate possible halftone regions based on a decision function. A color halftone descreening technique based on the color sigma filter is proposed which does not assume any a priori knowledge about the halftoning process, making it applicable to any color halftone image. Combined with color halftone segmentation techniques, a complete document processing algorithm for color documents is proposed. Experimental results are offered to illustrate the performance of our algorithm.

Formulation of the moiré patterns formed by superimposing of gratings consisting topological defects: moiré technique as a tool in singular optics detections

Abstract: The use of moire pattern of superimposition of linear forked gratings (LFGs) and Fresnel zone plates (ZPs) has already been reported for study of different physical effects In spite of a considerable number of applications, there is no comprehensive formulation for this kind of moire pattern In this work, we introduce a new family of ZPs containing topological defects that we named defected ZP (DZP) and we present a very simple, uniform, and comprehensive formulation for the moire pattern of superimposition of two LFGs, two DZPs, and superimposition of an LFG on a DZP, using the reciprocal vector approach For the case of the two LFGs superimposition, we show that the resulting moire pattern has a starlike shape or is a large-scale LFG pattern In the case in which two DZPs are superimposed, we show that the resulting moire pattern has three general forms: large-scale DZP pattern, starlike pattern, and large-scale LFG pattern In the superimposition of an LFG on a DZP, in special conditions a new spiral ZP having a topological defect is produced in which its defect number related to the superimposed gratings structures The presented formulation has potential applications in singular optics measurements

Multipoint diffraction strain sensor: theory and results

Abstract: A multipoint diffraction strain sensor has been developed using a moire interferometer with the novel added feature of whole-field strain determination. This unique feature has been implemented by simultaneous tracking of sampled wavefront diffracted from the component under test. In this sensor a high-frequency diffraction grating is bonded on the specimen, which is illuminated by two symmetric collimated laser beams, as in a typical moire interferometer. The first orders of diffracted beams impinge on a CCD camera, via a microlens array. The lens array serves a dual purpose—to sample the diffracted wavefront and to focus the wavefront to a number of spots on the CCD. The deviation of the individual spots generated by both the beams is directly proportional to the normal strain and a component of the shear strain. Simultaneous strain measurement at more than a thousand points can be readily obtained and is demonstrated in this paper. This novel technique is expected to be very valuable in numerous industrial metrology applications.

Numerical evaluation of moiré pattern in touch sensor module with electrode mesh structure in oblique view

Abstract: Capacitive touch sensor screen with the metal materials has recently become qualified for substitution of ITO; however several obstacles still have to be solved. One of the most important issues is moire phenomenon. The visibility problem of the metal-mesh, in touch sensor module (TSM) is numerically considered in this paper. Based on human eye contract sensitivity function (CSF), moire pattern of TSM electrode mesh structure is simulated with MATLAB software for 8 inch screen display in oblique view. Standard deviation of the generated moire by the superposition of electrode mesh and screen image is calculated to find the optimal parameters which provide the minimum moire visibility. To create the screen pixel array and mesh electrode, rectangular function is used. The filtered image, in frequency domain, is obtained by multiplication of Fourier transform of the finite mesh pattern (product of screen pixel and mesh electrode) with the calculated CSF function for three different observer distances (L=200, 300 and 400 mm). It is observed that the discrepancy between analytical and numerical results is less than 0.6% for 400 mm viewer distance. Moreover, in the case of oblique view due to considering the thickness of the finite film between mesh electrodes and screen, different points of minimum standard deviation of moire pattern are predicted compared to normal view.

Real-time analyzer of displacement and strain distributions using moiré method

Abstract: A system for real-time measurement of deformation of structures by processing the grating images of the structures obtained by a TV camera has been developed. The advantages of the system are: (1) the method is whole field, noncontact and produces a real-time measurement; (2) wide application of this method is possible. Displacement and strain distributions on any size of surface and any material can be measured if a grating can be drawn or projected on the material or a carrier fringe pattern can be obtained and recorded by a TV camera; and (3) motions of objects may be detected in real time using this system.