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On Mon, Jan 04, 2021 at 10:37:34PM +0100, Frank Steinmetzger wrote |
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> |
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> When I edit photos, I like to shrink and recompress them to save on |
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> space, but not mangle them too much in the process to lose quality. |
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Actually, shrinking *BY AN INTEGER NUMBER SHOULD IMPROVE QUALITY* as |
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well as saving space. In Google look up the phrase... |
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photography binning adjacent pixel |
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If you bin a 3840x2160 image by 2, you'll get a 1920x1080 result. If |
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you bin it by 3, you'll get 1280x720 image. The math is a bit |
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convoluted, but when you bin by a value of "n"... |
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* the information per combined pixel increases by a factor of "n" |
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* the noise per combined pixel increases by a factor of square root of "n" |
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So the "signal-to-noise-ratio" increases. The resulting image is less |
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noisey. The tradeoff is that the new image is smaller than the original. |
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I use the imagemagick "convert" utility from the commandline, but any |
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capable image software should work. |
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-- |
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Walter Dnes <waltdnes@××××××××.org> |
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I don't run "desktop environments"; I run useful applications |
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