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Sharpening improves "acutance"; your perception of boundaries. https://en.wikipedia.org/wiki/Acutance https://en.wikipedia.org/wiki/Acutance Unsharp masking is
by neilk 13y ago
Sharpening improves "acutance"; your perception of boundaries. https://en.wikipedia.org/wiki/Acutance https://en.wikipedia.org/wiki/Acutance
Unsharp masking is mostly aesthetic. For an image like the example, a mountainside, it gives you a feeling of crisp details, but there isn't any more data there. It looks great on a landscape, but it can be disastrous on a portrait of a person (pores and stubble will be highlighted, usually in an unpleasant way).
(EDIT: incorrect assertion about unsharp masking before or after scaling removed)
Sometimes it's better to unsharp-mask it to a degree that looks slightly oversharpened at a large size, but looks great when reduced - especially for very small images, like avatars or other icons.
- dietrichepp 13y ago> I have found that unsharp mask is best applied before you scale the image. Shrinking the image first will eliminate some of the details that you wanted to enhance in the first place. Unsharp mask doesn't work that way: you get the same results applying it before or after scaling, as long as you adjust the radius accordingly. The reason I suggested applying it after scaling is because aesthetically pleasing settings don't change much as the image size changes.
- neilk 13y agoI tested this with a couple of images and you are right. Except for a few errant pixels here and there the images are precisely identical. Sorry for the misinformation.