[Leica] Sharp lenses, who cares?

[phong at doan-ltd.com (Phong)]

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,

- Phong