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.

Moire pattern resulting from superposition of two zone plates.

Abstract: The moire pattern resulting from superposition of two zone plates is analyzed in a general manner. Characteristics of the moire pattern and hence its reconstructed ghost images are so tabulated that visualization is made easier. Experiments are performed to substantiate the theoretical predictions, and their results show perfect agreement.

The Moiré Phenomenon

Abstract: A simple mathematical analysis using the shadow method is used to predict the shape, disposition, and spacing of moire fringes produced by two parallel-line grids. The method is extended to grids of regularly spaced closed-nested-plane figures and then to repeated cell structures. Generalizing, it is shown that for any species of grid “moire magnification” results. The linear and angular displacements of the fringes are related to the relative rotation and displacement of the grids to show the applicability of moire fringes as a sensitive tool for positioning or for measuring very small displacements and rotations. A brief discussion is presented of the use of the phenomenon as a visual aid in the classroom.

Moire Factors And Visibility In Scanned And Printed Halftone Images

Abstract: Unacceptable moire distortion may result when images that include periodic structures such as halftone dots are scanned. In the frequency domain, moire patterns correspond to visible aliased frequencies. In the spatial domain, moire patterns are evident as cyclic changes in the size of halftone dots, producing visible periodic "beat" patterns. Moire pattern formation depends on the following factors: (1) the halftone screen frequency, (2) the scan frequency, (3) the angle between the scan direction and the halftone screen, (4) the scanner aperture size and shape, (5) quantization errors from the thresholding operation, (6) scanner and printer noise, and (7) the ink flow in the paper during printing. This paper analyzes the visibility of moire patterns in terms of these factors. In addition, the paper describes an approach to reducing the visibility of moire patterns by directly manipulating the moire formation factors. With an appropriate selection of the scan frequency and screen angle for a given screened image, moire beat frequencies in the scanned image can be reduced to a subvisible level. This approach thereby achieves moire reduction without the need for scanning at extreme scan frequencies or postscan image processing. The strengths of this ap-proach are (1) no data volume increase due to high frequency scan and (2) no need for time-consuming postscan processing. Computer-simulated and actual scan images are presented to illustrate the approach.