Archived posting to the Leica Users Group, 2004/06/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Phong said the following on 6/8/2004 7:33 AM: > > Richard F. Man wrote, about Unsharp Mask: > >>So in layperson's term, exactly what does these settings do? > > > I'll take a shot at answering your question. > USM creates hightlight "grooves" along shadow / highlight > edges to inscrease the contrast along those edges. As we > know, increasing the contrast gives the illusion of "sharpness". > > "Amount" specifies how "deep" these grooves are. Depth is > measured in terms of the difference between the shadow and the > highlight. > > "Radius" specifies how "wide" the grooves are, measured in pixels. > > "Threshold" specifies how big the difference between shadow > and highlight must be before the mask is applied to an edge. > > Hope that helps, ... All true -- I think what Richard was asking was why/how weird settings with a very large radius work. Normally, sharpening happens with a small radius from .5 to 2 0r 3 and a large amount50% to 500%. With a large radius -- like 60 or 70, and an amount of about 30%, it makes the picture "glow" -- sort of enhances clarity. Looks very different than the usual sharpening effect. I like it (sometimes). Gives the Leica "glow" to any camera :-) -- Clive http://www.pbase.com/chmoss/root