[Leica] That Leica Glow

[bdcolen at earthlink.net (bdcolen@earthlink.net)]

I re below -
When converting to black and white, I now routinely to an "unsharpen mask" 
at the start of the process with an amount of of about 15%, a radius of 
about 55, and a threshold of 1 - which doesn't appear to "sharpen," but 
instead appears to bump up the contrast, creating more of a traditional 
"tri-x bw" look. Then, after doing whatever other work I'm going to do, I do 
a "normal" unsharpen mask at the end.....

B. D.



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 :-)