Superimposition: Difference between revisions
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{{Wiktionary}} |
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In [[graphics]], '''superimposition''' is the placement of an [[image]] or video on top of an already-existing image or video, usually to add to the overall image effect, but also sometimes to conceal something (such as when a different face is superimposed over the original face in a [[photograph]]). |
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This technique is used in [[cartography]] to produce photomaps by superimposing grid lines, [[contour line]]s and other linear or textual mapping features over [[aerial photograph]]s. |
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Superimposition of 2D images containing correlated periodic grid structures may produce [[moiré pattern]]s. Superimposition of two correlated layers comprising parallel lines or curves may give rise [[line moiré]] patterns. The movement of one of the layers results in a faster movement of the [[line moiré]] superimposition image. Such optical acceleration is known as [[moiré speedup]] (check for the formulas of optical speedup for curved patterns). When superimposing two identical layers comprising randomly spaced parallel lines, at a small angle or with a small scaling difference [http://switzernet.com/people/emin-gabrielyan/070227-random-line-moire/ random line moiré] patterns, namely line Glass patterns (after Leon Glass, 1969) appear. Similarly, when superimposing two identical layers of randomly scattered dots at a small angle or with a small scaling difference random dot Glass patterns, namely [http://switzernet.com/people/emin-gabrielyan/070212-random-moire/ random dot moiré], appears. When one of the layers embeds complex shapes, such as sequences of symbols forming a text, and another layer contains parallel lines or curves, the superimposition image may gives rise to magnified shapes, called [[shape moiré]] patterns. |
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== References == |
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<references/> |
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[[Category:Printmaking]] |
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[[Category:Printing]] |
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[[Category:Artistic techniques]] |
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[[Category:Cartography]] |
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[[ja:スーパーインポーズ]] |
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[[simple:Superimposition]] |
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Revision as of 20:32, 8 October 2008
ADAM SANLER