On 26/02/14 21:00, Christian Sinn wrote:
> I did a denoise comparison of darktable (DT) with rawtherapee (RT) and 
> lightroom (LR) because my photos shoot with ISO 1600 are very noisy and 
> I found no way for a satisfying result.

I use a dual denoise approach, as recommended in the manual, using Denoise 
(profiled):

"This module can eliminate noise with two different core algorithms. “non-local 
means” is a bit better suited to tackle
luma (lightness) noise; “ wavelet” has its strength in eliminating chroma 
(color) noise. If needed you can apply two
instances of this module (see Section 3.2.3, “Multiple instances”). The 
“non-local means” instance should be combined
with blend mode “lightness” or “HSV lightness”; the “wavelet” instance with 
blend mode “color” or “HSV color”."

http://www.darktable.org/usermanual/ch03s04s04.html.php#denoise_profiled

So basically I do:
* wavelets, strength 1, blend mode color.
* non-local means, strength 0.5, blend mode lightness.

You can also have a look at the video I did on the denoise tools in darktable, 
though I compare darktable to AfterShot
Pro with NoiseNinja.

https://www.youtube.com/watch?v=4nBzAeM0tpI&list=PLmvlUro_Up1NBX7VK8UUuyWo1B468zEA0&index=4

Also, from a previous email from Johannes to this list:

"the profiled denoising is based on assumptions (the noise model) which break 
down in dark areas for quite a few
cameras. in my experience images with dark background and piecewise-constant 
characteristics, the non-local means
denoising module can work better (starry skies, probably fireworks, too). in 
case you want more fine grained control
over the wavelet shrinkage used in profiled denoising in wavelet mode, it's 
basically the same method as employed in the
equalizer. it's also a good idea to try color-only blend modes (hsv color, as 
described here
http://www.darktable.org/usermanual/ch03s04s04.html.php#denoise_profiled)."

By the way, "wavelet shrinkage" is controlled by the "sharpness" tab of the 
equalizer.  More on that in (you guessed it)
another one of my videos:

https://www.youtube.com/watch?v=zzVXK4eAM5E&list=PLmvlUro_Up1NBX7VK8UUuyWo1B468zEA0&index=16

Hope that helps.

Regards,

Rob

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