Dear @rawfiner
I see your point, I checked the video, I cannot explain as well. Anyhow, I agree with you, don’t get too much headaches and use the new NLM (auto if wanted)
I donno whether you have tested with astro fotografie as well. IT IS AMAZING!!!
Thank you for everything!
Sincerely
Axel
I’m the one asking to keep them 
I do still use the chroma one, it produces grains on the picture but the print is really clean anyway. I’ve just printed a set of 40 pictures in A3+ and A2 for an exhibition, all pictures shot between 3200 to 5000 ISO and the print are clean. The visible grain on screen when you zoom is un-noticable on paper and I find the render better and sharper.
That being said, if it proves to raise more confusion I’m ready for a PR to remove them as I can easily add my own presets anyway.
Maybe just rename them then? People won’t read the release notes and will still use the old way
Alright, tried the new denoising technique on a few images and I remain unconvinced.
Not the new parameters or the recommendation/suggestion to use NLM in auto mode “always”, i.e. regardless of whether it’s chroma or luma noise.
I’m not sold on the idea to avoid blending modes. You specifically said that you are not using blending altogether, but more generally that no one should use HSV color or HSV lightness blending modes.
First example (this particular image is probably worst case scenario, a daily scene shot at ISO 51200 with my Fuji):
On the left, NLM auto, all defaults. On the right, the classical preset for chroma noise (wavelets mode blended 100% in HSV color). Screenshot from 100% zoomed in image.
The NLM auto applied brutally like so gives me the impression of the usual heavy denoising applied in camera which I dislike, with mushiness and destruction of details (I know, mostly noise but the impression that I get is of higher definition and more realistic == less “digital”).
So now compare the classic denoising as above (right) with the NLM auto blended in normal mode at 50% (left):
This is better than before for me, but is it better than blending in hsv color?
Same photo, a detail of the sky:
(Zoom all the way in to see what I’m talking about).
On the left again NLM auto 50% blend normal; on the right wavelets blend 100% HSV color. What’s better? The trees are possibly more detailed on the right, and the sky – yes there’ a noisy pattern but it’s mostly monochromatic and more “organic”, I think I like it more!
However, I move to another image, this is shot with a m4/3 camera at very high ISO (16000!) under artificial light. Again just an example! Apologies for the very poor snapshots I’m using here!
In this case the comparison is between NLM-auto-no blend (below), with rather aggressive parameters (central pixel weight 1.00, adjust autoset 3.59, strength 1.3) and the standard chroma denoising above (default parameters as in previous examples). Now I’m confused because the first method is much better! There still is some ugly chroma noise left but that is impossible to remove I think.
So there you go. I think I had a point,. that blending in HSV color still works better but I have a random collections of (mostly poor) images that maybe are better processed with the new approach, i.e. without any blending.
Perhaps for the rest of today I should process clean, low ISO photos.
Better seems to do with the fact that one side of the comparison has more grain. If we matched the graininess, would your choice still be the better one?
I haven’t gone through thorough tests as @aadm, but have picked some late edits and swapped the old couple denoise chroma + denoise luma for the new nlm and got excellent results, after I learned in this thread how to do it right.
In the end, I find the new nlm easier to tweak, and in a more flexible way. For example, removing (or mitigating) dark blotches in very underexposed or high iso images, which, in the old way, I had enormous difficulty to deal with.
All in all, I’m very happy with it so far.
I am also quite happy with the current denoise.
One thing very interesting, when I work in 100% mode, the picture looks sometimes a bit worse or at least not that pleasing, but when I zoom out to full view (finally relevant), suddenly you can see a big improvement in microcontrasts with the new NLM method
I just sometimes would like to have a wider range of the auto-sliders. Sometimes I have them at the end and still not totally happy 
In my humble opinion, lowering opacity works well for low and medium ISO images, but less well in high ISO images.
In that case if you want grain, I would push central pixel weight, and reduce strength if needed.
I almost always use NLM, but I also always tweak its parameters, I find the default force value almost always too strong 
Try doing the same approach (tweaking the 3 parameters instead of just reducing opacity) with the others images
Also, it’s not a big deal if some chroma noise remains at 100% zoom level, if you don’t see it when zoomed out
Anyway, things I say are only advices, you can still use color blending modes if that suits your need.
Happy to hear that
Thanks!
You do have a wider range, for almost all parameters of denoise profiled
You can enter values outside visible bounds by keyboard. The real ranges are:
Have a look at this: https://www.youtube.com/watch?v=UuB9khJIrDI
Aurélien explains quite a lot of things in this video, it should makes things clearer
Happy to help
Presets still have some interest IMHO, as they show examples on how to use wavelets curves, and some people like the results they have with them, so it makes sense not to deprecate them too early to give some time to people to change their habits if they want to I guess
@rawfiner, thanks for all your hard work on denoising. I’ve been getting excellent results with the NLM auto on my sports pictures taken at night. Sometimes I have to make a minor tweak, but most of the time it’s good.
I agree with keeping the presets. I still use the chroma preset when denoising low iso color noise or color noise introduced when I use some of @s7habo’s excellent editing techniques. I also think that a lot of work went into figuring out those curves, and it shouldn’t be lost.
Finally, I think NLM auto makes easy denoising accessible to the masses.
Thanks again for all your hard work,
Bill
Just checked this out and I must say I am impressed with the result… though its slower than old denoise.
A few spontaneous thoughts from a user: 1. I miss a slider for adjusting chroma denoise. 2. Do not remove the old presets please, they were introduced just 1 year ago I think. Old denoise is faster and useful when noise is not so strong. And some users like what they are used to. Though I admit it is somehow misleading.
I’m not using darktable, but how is the new noise reduction compared to RawTherapee ?
In terms of quality/result similar, maybe a little bit better. In terms of speed, worse. But the math behind it seems to be different, and so the usage is different, too. I don’t know. I still think RT is better in terms of sharpening/demoisaicing/noisereduction/resolution, but dt has other advantages. New denoise in dt is certainly much better than old denoise, especially with high iso shots. Overall new denoise is simlar to RT. If you want to use new denoise you should have GPU acceleration (OpenCL), otherwise it must be really slow.
Ok, thanks. I’m using RawTherapee a lot, but if I encounter a high iso noisy image , I skip RT and do all my edit in DxO.
PRIME Noise reduction is also slow/very slow. 
You can use the central pixel weight and the force sliders to get an effect similar to what a chroma slider would do
There is no plan yet to remove them (although they have been adjusted a bit to prevent highlight clipping)
Chroma noise doesn’t exist. It’s just noise that doesn’t affect the 3 RGB channels at the same time.
Great work on the noise reduction 
I find the ‘preserve shadows’ slider very useful. In darktable 2.6 I sometimes used a parametric mask to increase the denoise intensity in darker areas, the new features make that much easier.
This is a photo without denoise:
This is with the default settings in profiled denoise:
And finally with a lower value for shadows preservation:
In my experiences with the new profiled denoise the loss of detail is very low, the darker parts become a bit darker than before and you lose a bit of sharpness in the image. But you can easily compensate that.
