Another way to boost heavily under exposed images that scales the highlights away from black is to use fusion and multiply exposures in the base curve tool. The XML files I attached above will show I used two base curve tools and pulled the highlights more in the curves and with multiplication.
Hi’
I think that your result using RT is the best of all attempts because the resulting image contains “gentle” noise that looks natural in a pleasant way in close up.
Your settings are very close to my settings except I used the LAB color space which is the default. The RGB color space setting leaves pronounced noise before the final touches. Can this be explained or is it “just the way it is”?
Below you will find the result of your settings with the LAB color space, your settings with the RGB color space and your final result after touch up. Big differences! Could you please explain your final touches in more detail and/or upload the pp3 file?
Here’s a pp3 that works with RT 5.5. It’s not identical to the previous one, but noise-wise it’s pretty close.
DSC_0629.jpg.out.pp3 (11.9 KB)
Thank you for the pp3-file.
When I use my original pp3-file, change the color space to RGB and change the chrominance curve from linear to equalizer I get a result very much the one you posted. The Chrominance curve has a big effect.
odd, in my tests I found it to have zero impact. I might have done something wrong though, I will re-evaluate
I like your pp3, being straightforward and effective.
(But the chrominance curve has a big impact here too. 5.5-243 win.)
When I use my original uploaded pp3 then the chrominance curve has a big effect in RGB color space. This is also the case if I set the denoise parameters equal to your settings. If I use yours pp3 the effect is very limited???
Hi’
The surprising difference in the pictures below is caused by difference in the demosaic settings.
I thought that LMMSE was recommended for noisy images, but the result is clearly not good in this case. Good guidelines will be appreciated…….:o)!
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Well, the false color correction steps setting (which is applied after demosaicing) is not the same in your comparison…
I don’t understand what you are trying to tell me.
The difference between the two images is caused by changing the following RAW settings (by copying the settings from another profile) Demosaic method, Pixel Shift and False color suppression. Where are Pixel Shift and False clolor suppression situated in the raw settings?
Normally I would never try to change these settings since I don’t understand what they are supposed to accomplish. I my standard profile I just changed the demosaic method to LMMSE (recommended in Rawpedia) then the rest came by default.
Since the difference is so big some guidelines would be very nice…
Look at the 2nd slider in you demosaicing settings screenshots. You’ll see that you have false color suppression set at 2 for LMMSE, whereas it is set at 0 for AMaZE.
For better comparison, turn both down to 0, or set both to 2. The result could be different from what you observed at first.
fwiw I always use amaze. I did try others in the past, but for my camera amaze always delivers (sometimes I need to tweak the black levels though)
Last week I’ve participated to a discussion on dpreview, where we showed that under some circumstances, the LGV algorithm is good to remove Moiré patterns (in that case, the Moiré was caused by the pattern of windings around some guitar strings, and AMaZE was worse).
Edit: but the images were not noisy, so I was digressing a bit
Hi’
You are absolutely right. Changing the “False color suppression” makes a very big difference both with LMMSE and AMAZE. The results get worse every time the setting is increased both in AMAZE and LMMSE. You would expect the opposite would you not?
The results are best when the setting is zero (and the LMMSE enhancement steps are zero as well) but AMAZE is still the best choice.
What does the “Border” setting do? It’s not documented in Rawpedia.
Hi’
I also like your result. What is darktable master? It’s not possible to enter these settings in denoise(profiled) version 2.6.0.
At the default setting of 4 a 4 pixels border will be skipped because it can not be demosaiced in the same quality (missing pixels at at least one side).
As a consequence, in past, demosaicing full hd video raw files (1920x1080 pixels) always resulted in smaller output (1912x1072 pixels) .
For that reason rt now allows to set the border to zero to get the full sized image (though with reduced quality at the 4 pixels borders).
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darktable master corresponds to the development version of darktable, so you will have to wait for darktable 2.8 (or to build darktable from the sources) to be able to use the same settings
Here is my take on denoising. Not as good as some of the above, but hey it’s me fooling around using unconventional means, without the help of the usual tools. 
As usual, the minimalist approach.
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Hi’
Thank you for your response. Im curious to know what those unconventional means are……?
Approach
Generally, I treat my processing workflows as a science experiment. I tested the ideas that I had and used the best combination of them to come up with the result that I could appreciate. Will inevitably not generate as many likes but that isn’t the point. The point is the process and having fun doing it, hopefully learning something new along the way.
Objective
Objectively and subjectively, there are many views on how noise should look like in a photograph, some of which were talked about in this thread. My goal was not to emulate real life grain nor make the image devoid of noise. I was to make it look pleasant; make the noise less of a distraction from what would otherwise be an excellent image.
Method
I am aware that there are filters, commands and apps made by people who are way smarter and much more proficient than me; but I normally script my own with G’MIC using my own ideas for the thrill and challenge. Just a newbie trying to learn at a breakneck pace. Occasionally, I discuss them openly, usually when I think the ideas are good enough to share to the wider community.
Conclusion
This is a long way of saying that even if I told you the exact details, it wouldn’t be meaningful for general use. I haven’t shared the scripts that I have been working on since they aren’t ready. In this sense, I am similar to @agriggio and his custom RT.
In the PlayRaws, I do however itemize and share the sequence of processing step. Very clearly in fact to give people a sense of how they could achieve a similar result using their preferred tools. Recently, I have decided to not be as thorough, since it takes effort to write up a step-by-step workflow that no one else does. But since you asked, these are the strategies that I used in the final result.
0. Unclipped linear sRGB from PhotoFlow.
1. Preprocessing.
2. Flatten troublesome impulse noise.
3. Guided smoothing with guided filter.
4. Rolling guidance with bilateral filter.
5. Curve manipulation with wavelets.