Siemens star
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A Siemens star is a device used to test the resolution of optical instruments, printers and displays. Theoretically the spokes never meet at the centre of the star as the gap between the spokes is gets infinitly smaller as you approach the centre. When printed the smallest gap is limited by the smallest dot of ink the printer can produce and is therefore a useful tool for comparing two printers' resolutions (DPI). A similar principle can be applied to a camera's optical resolution by taking two photographs of a Siemens star printed at high resolution and comparing the photographs to see which camera retained the centre detail the closest.
Siemens stars are also used in graphic design as a background as in the Japaneese Naval Ensign, they are useful in drawing the eye to a point on the page. Graphic designers usually call them Sunbursts.
External links
- [ISO 15775 chart(pdf)] resolution test chart featuring a vector siemens star
- [Creating Sunbursts] tutorial on creating Siemens Stars in Adobe Illustrator
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