I am finding that I often prefer raw denoise to denoise (profile) - both non-local means and wavelets. I don’t get any of the artifacts, like the oil-painting effect from wavelets.
Is there a downside? Well, of course, it is not profiled to the ISO used, but I could set up a range of raw denoise auto-apply defaults for different ISO ranges.
Other than that, I also sometimes use mostly raw denoise, then lightly apply a small amount of wavelet denoise.
Raw denoise often gives me ‘salt and pepper’ noise. Have you tried chroma-only mode for profiled denoise, and/or fine-tuning the curves?
If you raise the right hand end of the graph in raw denoise, you can eliminate the salt and pepper noise. It’s not an artifact, it’s just noise not eliminated yet.
Good idea to try chroma only, but I would use that after the raw denoise. That would work well I expect.
Well I hope I am not just adding noise to this conversation 
. But I opened an image shot from a Canon G16, which is a quality compact camera, shot at 1600 ISO. I applied no processing to the image and have cropped a section of the image for comparison. The section on the left has no noise reduction, the centre one has denoise (profile) at default settings, and the one on the right has RAW denoise default settings. For my two cents worth, I find the denoise (profile) has become my default denoise method. With really troublesome images I may also recruit various other modules including the Contrast equalizer module and maybe even Raw denoise. I feel the denoise (profiled) module works so much better since DT V4.0 for my cameras.
haha
I think the difference is, I am trying to reduce noise to the point where you cannot see it. It is still quite visible in th examples you posted. When you try to reduce it more, the artifacts start to appear.
I am not sure if such an extreme noise reduction is necessary or beneficial. In the days of film we always had grain in the image. So I can live with that. In the image I posted it was a street screen shot at night, in a laneway in Vietnam with a deliberately small camera. The ambience is more important than the lack of minor noise to me.
But going back to the purpose of the original post I was comparing the default settings of two denoising options. When I have really troublesome images I am more experienced at working with the options in Contrast Equalizer to tackle the remaining luma noise left over from denoise (profiled). My experience with Raw denoise is a softening of image details. I am happy to stand corrected on this by a user such as yourself who has invested more time in that particular module’s options.
I would agree without tweaking and even then it usually kills detail using raw Denoise. The best video on denoising are made by rawfiner…the module creator… his version made with 2.6 covers using raw Denoise color channel by color channel by color channel…even too much color denoising can start to desaturated the image…
I appreciate that input. Yes, I had a niggling feeling that using raw denoise too heavily was compromising some detail. I need to play more with contrast eq.
OK. Seems I need to refine what I am doing. Thank you
there’s nothing wrong using raw denoise if it gives proper results for you.
There’s no better or worse if the result is ok for you.
Using darktable it‘s worth to keep in mind: there’s no one size fits all.
So the headline news a little amendment: … for images from my camera the way I process them.
There are several ways to denoise because all of them have their strength and weaknesses. It’s the result that counts, not the modules used …
As Martin says they all have strengths and weaknesses . My point was that out of the gate I think raw denoise is pretty heavy handed. In away most of them can use some tweaking and dialling back…
The YT video made some time ago by rawfiner is a nice overview of how to do that tweaking using the various modules in DT. All his videos are worth watching. This one is really good. A couple of the modules now have new names but the approach does not change…Denoising with darktable 2.6 - YouTube
@n01r , maybe you could post a raw and a sidecar to show how you process it, and we could try to come up with alternatives?
When the image is noisy, I don’t try to remove all of the noise, just reduce it. Noise destroys data; smoothening the noise completely will create the watercolour look. I try to get rid of chroma noise, and rarely apply luma noise reduction, as I find it hard to keep the details. Some of this is a matter of taste.
I am not doing anything fancy, just raw denoise and denoise (profile) wavelet. I try to remove noise until it is not visible in the final image at expected viewing size.
As you say it is to taste, as is sharpening, and in some areas of photography, people can get very picky. I am happy that I can reduce it enough for my needs. I was just observing that, if I do it with Denoise (profiled), I get more artifacts, than raw denoise, but as someone said, maybe I am losing more detail with raw denoise. Anyway, no matter the method, I take the advice not to go too hard.
As kofa says it would be good to see an example. Then we are all talking about the same thing when we make comments. With the xmp files we can all see what settings and other modules are being used so we understand the full picture. For example it would be good to see what you call artifacts.with profiled denoise also when I have played with raw denoise in the past it has been my experience that just turning it on obliterate the detail so I am sure you tweak it and it would interesting to see your process
I just use the “chroma only” preset in denoise profiled, and that’s it. The remaining monochromatic noise is a part of my photo and it doesn’t bother me. I love that preset and I no longer stress about noise.
@n01r : if the purpose of the topic is to teach, to explain a technique you find useful, examples really help a lot. If the purpose is to ask for advice, then again, examples can show what you are struggling with.
The reason I use the contrast equalizer module to tackle luma noise is that it has minimal loss of detail because you can control the size of the wavelets being tackled. The denoise profiled tends to handle chroma noise beautifully and reduces luma noise. With contrast equalizer I only worry about the luma noise.
The sample image attached is left panel no noise reduction, centre panel denoise profiled, and right panel denoise profile and Contrast Equalizer used as shown in separate image. All of these panels have demosiacing sharpening from the new diffuse or sharpen module. Considering the high ISO and small image sensor I am more than happy with this result. Only a small section of the whole image is shown here.
Thanks everyone. My question has been answered. I really just wanted to know if using raw denoise had any major downsides, and it seems maybe loss of detail would be the main concern.
Thanks for the examples.
denoise (profiled) also supports controlling noise suppression by detail levels. Have you tried that? Any experience with diffuse or sharpen to filter noise (it has some denoising presets)?
The truth is that I am so happy with the default settings on denoise profile with my camera images that I have not invested time yet into manually tweaking it. With really noisy images I increase the strength of the default values. When I have a suitable image that justifies the time I may explore what you are suggesting.
