Digital photo de-noising software suggestions?

[Walter Dnes]

  Linux-based of course.  I currently have rawtherapee, imagemagick,
ufraw, gimp, and gmic on my disk, for various reasons.  I took my Canon
S100 out for a torture test today, to see how high I could push the ISO,
before it got badly noisey.  I noticed that the jpeg is a lot cleaner
than the output from the RAW, probably due to in-camera processing.  The
question I have is how do I do it.  For a comparison, compare the blue
sky in the upper left corner of the 2 images...
http://www.waltdnes.org/misc/IMG_0118.png (warning 25 megabytes)
http://www.waltdnes.org/misc/IMG_0118.JPG (warning  3 megabytes)

  The png was obtained from the raw CR2 image by rawtherapee.  The JPG
comes direct from the camera.  A Google search turns up technical
discussions about "radius" of smoothing, which I don't understand.  E.g.
The ufraw-batch command has a "--wavelet-denoising-threshold" parameter.
And the ufraw gimp plugin has a "Denoise" slider.  Is there a simple
layman's explanation somewhere, and a list of suggested parameters to
use?

-- 
Walter Dnes <waltdnes-SLHPyeZ9y/tg9hUCZPvPmw at public.gmane.org>
I don't run "desktop environments"; I run useful applications
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