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Nicolas Robidoux has a page on advanced resizing techniques here: http://www.imagemagick.org/Usage/filter/nicolas/ http://www.imagemagick.org/Usage/filter/nicol
by mrob 11y ago
Nicolas Robidoux has a page on advanced resizing techniques here:
http://www.imagemagick.org/Usage/filter/nicolas/ http://www.imagemagick.org/Usage/filter/nicolas/
Resizing in a sigmoidized colorspace has impressive results with many images. I find it works particularly well with images that should have been saved as vectors, especially when used with eliptical weighted average filters (-distort Resize). It significantly increases sharpness while causing artifacts that are difficult to notice because they don't look like any traditional image processing artifacts.
The same technique is also available in MPV for scaling video.
- bryanrasmussen 11y agojust curious - do you know of any way that will detect if images should probably have been saved in vector format - the detection should be reasonably performant so it isn't wasteful to check before deciding which optimizer to use.
- mrob 11y agoRecent versions of Imagemagick support entropy measurement, which is typically lower in diagram/line art type images. You can check it with 'identify -format "%[entropy]" filename.png'. Some quick testing suggests photographic images usually measure greater than about 0.8.