Topic
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.
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TL;DR: In this article, the Fourier transform method of fringe analysis is applied on the grating images recorded before and after deformation, and the deformation field is obtained by comparing the phase map of a grating before deformation with that after deformations.
2 citations
10 Dec 2002
TL;DR: An adaptive method for smoothing the moire patterns in image space is proposed in this paper, which uses moire strength information that is determined off-line by analyzing interference between different color halftone patterns.
Abstract: The color inverse halftoning technique was developed for the use of scanned color halftone images in digital applications, which is basically a smoothing method of halftone patterns. Smoothing of the moire phenomenon in color halftoning unfortunately leads to excessive blurring of the boundaries because moire patterns form very low-frequency peaks in the spectral domain. An adaptive method for smoothing the moire patterns in image space is proposed in this paper, which uses moire strength information that is determined off-line by analyzing interference between different color halftone patterns. The information is stored in tables and is looked up directly with color values of each pixel, so the proposed method works very fast. Through several experiments, we found that our experimental method smoothed moire patterns well without blurring the boundaries much.
2 citations
TL;DR: It is demonstrated that the deformation of moiré fringes does not originate from the wavefront derivative, but superposition of two separated wavefronts causes fringe deformation.
Abstract: In a deflectometry experiment for finding the temperature distribution around a hot wire as a phase object, the trace of the wire in a moire pattern is duplicated, and it is observed that the separation of the wire traces varies when the distance between two gratings of a moire deflectometry setup is changed. By investigation of moire deflectometry, it is found that the object trace duplication cannot be interpreted by ray deflection theory, which is based on geometric optics. By using diffraction theory, the effect of a phase object on a moire pattern is studied, and some generalized formulations are presented. It is demonstrated that the deformation of moire fringes does not originate from the wavefront derivative, but superposition of two separated wavefronts causes fringe deformation. By this approach, the accuracy of ray deflection analysis is improved. Finally, the results of this model are simulated, and the simulation has good agreement with the experimental model.
2 citations
Patent•
10 Apr 1998
TL;DR: In this article, an interferometer 100 generates an interference fringe image with a light wave surface containing a form information of a sample surface, and a computer 11 calculates based on pixel information recorded in an image memory MAX 10a and MIN 10b to adjust a level for each pixel.
Abstract: PROBLEM TO BE SOLVED: To raise the accuracy of measurement by detecting a sample image which is obtained by making a measuring light wave interfere with a reference light wave, and generating a moire fringe image by inter-image multiplication of a sample image signal and each of plural reference images, for calculation process. SOLUTION: An interferometer 100 generates an interference fringe image with a light wave surface containing a form information of a sample surface. A 2D image detecting means 1 inputs the interference fringe image. An image inputting means 2 extracts a video signal for one screen. A computer 11 calculates based on pixel information recorded in an image memory MAX 10a and an image memory MIN 10b to adjust a level for each pixel, and prepares a reference image signal and writes it in reference image memories 3a, 3b and 3c. Multiplier devices 4a, 4b and 4c multiply the reference image signal and a sample image signal together. A moire fringe image of moire fringes, generated from the sample image signal and the reference image signal, from which a carrier component is removed, is displayed on a monitor 23.
2 citations
TL;DR: In this article, a projection-type moire topography that uses a frequency modulation technique with two liquid crystal digital gratings (LCDGs) is proposed to measure three-dimensional shapes and step heights.
Abstract: A projection-type moire topography that uses a frequency modulation technique with two liquid crystal digital gratings (LCDGs) is proposed. In this method, moire contours are filtered to remove the image of the original grating from the moire contours by moving the image created by the LCDGs. The frequency modulation technique can be used to analyze the fringe of step heights or other separate areas by modulating the fringe interval. The experimental results showed the possibility of measuring three-dimensional shapes and step heights.
2 citations