I'm trying to sharpen and denoise photographs from my Canon 7DmkII at
high ISO.  When I shoot basketball games, I'm forced to ISO 10000 or
thereabouts by our lighting (it was probably 1/3 stop too high as
you'll see, but that doesn't really change matters very much).  For
various reasons I'd prefer to use Darktable (for the most part it's
more powerful, it's much more stable, and I'm liking the interface),
but the noise reduction simply isn't acceptable.  Last night I was
forced to use both (initial processing with RawTherapee, including
exposure/lightness/saturation, and that since it interacts with NR,
and then cropping and watermarking with darktable because RT crashes
endlessly).

Reference https://rlk.smugmug.com/Photography/DarktableRawTherapee/
(which is a crop from the original).

The 7DmkII has a fairly aggressive optical low pass filter, so it's
well-advertised that shots from said camera need to be sharpened out
of the camera.  It's quite noisy at ISO 10000 (first shot in the
linked gallery), not too surprisingly, but I don't have much trouble
cleaning it up very nicely with RawTherapee (third shot), using
sharpen with Sharpen Only Edges enabled and straightforward noise
reduction (defaults for chroma, which isn't much of a problem here
anyway, and a good bit of Luminance and Luminance Detail).

It's a very different story with Darktable.  I can't get anywhere near
the combination of smoothness and sharpness whatever I do.  With
profiled denoise, some areas get denoised and some really don't;
adjusting the strength slider does have some effect here, but mostly
it just blurs out some areas while leaving some areas untouched for a
very unnatural effect.

Sharpening sharpens the residual noise as much as it sharpens the
edges.  I've attached the metadata files from DT and RT for
illustration.

The actual shot, fully processed and cropped (very differently) is at
https://rlk.smugmug.com/Sports/Basketball/MIT-SarLaw-mbb-20161126/i-chq2xjG/A
-- 
Robert Krawitz                                     <[email protected]>

***  MIT Engineers   A Proud Tradition   http://mitathletics.com  ***
Member of the League for Programming Freedom  --  http://ProgFree.org
Project lead for Gutenprint   --    http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton
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