Moiré

In physics, mathematics, and art, a moiré pattern is a secondary and visually evident superimposed pattern created, for example, when two identical (usually transparent) patterns on a flat or curved surface (such as closely spaced straight lines drawn radiating from a point or taking the form of a grid) are overlaid while displaced or rotated a small amount from one another.

The term originates from moire (moiré in French), a type of textile, traditionally of silk but now also of cotton or synthetic fiber, with a rippled or 'watered' appearance. Moire (pronounced mwar) and moiré (pronounced mwar-ay) are now used somewhat interchangeably in English, though moire is more often used for the cloth and moiré for the pattern.

 

Moiré

Pattern formation

Moiré patterns are often an undesired artifact of images produced by various digital imaging and computer graphics techniques, for example when scanning a halftone picture or ray tracing a checkered plane (the latter being a special case of aliasing, due to under sampling a fine regular pattern). This can be overcome in texture mapping through the use of mipmapping and anisotropic filtering.

Moiré

The drawing above shows a moiré pattern. The lines could represent fibers in moiré silk, or lines drawn on paper or on a computer screen. The nonlinear interaction of the optical patterns of lines creates a real and visible pattern of roughly parallel dark and light bands, the moiré pattern, superimposed on the lines.

More complex line moiré patterns are created if the lines are curved or not exactly parallel. Moiré patterns revealing complex shapes, or sequences of symbols embedded in one of the layers (in form of periodically repeated compressed shapes) are created with shape moiré, otherwise called band moiré patterns. One of the most important properties of shape moiré is its ability to magnify tiny shapes along either one or both axes, that is, stretching. A common 2D example of moiré magnification occurs when viewing a chain-link fence through a second chain-link fence of identical design. The fine structure of the design is visible even at great distances.

Moiré



In graphic arts and prepress, the usual technology for printing full-color images involves the superimposition of halftone screens. These are regular rectangular dot patterns—often four of them, printed in cyan, yellow, magenta, and black. Some kind of moiré pattern is inevitable, but in favorable circumstances the pattern is "tight;" that is, the spatial frequency of the moiré is so high that it is not noticeable. In the graphic arts, the term moiré means an excessively visible moiré pattern. Part of the prepress art consists of selecting screen angles and halftone frequencies which minimize moiré. The visibility of moiré is not entirely predictable. The same set of screens may produce good results with some images, but visible moiré with others.

 

Moiré



In manufacturing industries, these patterns are used for studying microscopic strain in materials: by deforming a grid with respect to a reference grid and measuring the moiré pattern, the stress levels and patterns can be deduced. This technique is attractive because the scale of the moiré pattern is much larger than the deflection that causes it, making measurement easier.

Moiré

Television screens and photographs

Moiré patterns are commonly seen on television screens when a person is wearing a shirt or jacket of a particular weave or pattern, such as a houndstooth jacket. This is due to interlaced scanning in televisions and non-film cameras, referred to as interline twitter. As the person moves about, the Moiré pattern is quite noticeable. Because of this, newscasters and other professionals who appear on TV regularly are instructed to avoid clothing which could cause the effect.

RECOMMENDED READING

 

Meggs' History of Graphic Design

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The bestselling graphic design reference, updated for the digital age

Meggs' History of Graphic Design is the industry's unparalleled, award-winning reference. With over 1,400 high-quality images throughout, this visually stunning text guides you through a saga of artistic innovators, breakthrough technologies, and groundbreaking developments that define the graphic design field. The initial publication of this book was heralded as a publishing landmark, and author Philip B. Meggs is credited with significantly shaping the academic field of graphic design.

Meggs presents compelling, comprehensive information enclosed in an exquisite visual format. The text includes classic topics such as the invention of writing and alphabets, the origins of printing and typography, and the advent of postmodern design. This new sixth edition has also been updated to provide:

  • The latest key developments in web, multimedia, and interactive design
  • Expanded coverage of design in Asia and the Middle East
  • Emerging design trends and technologies
  • Timelines framed in a broader historical context to help you better understand the evolution of contemporary graphic design
  • Extensive ancillary materials including an instructor's manual, expanded image identification banks, flashcards, and quizzes

You can't master a field without knowing the history. Meggs' History of Graphic Design presents an all-inclusive, visually spectacular arrangement of graphic design knowledge for students and professionals. Learn the milestones, developments, and pioneers of the trade so that you can shape the future.

2018 History Graphic Design

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