I'm using Darktable as my RAW processing software. In the darker images that have been taken with an ISO of 800 or more, I often find big problems with luminance noise.
The next two images (one of clouds and one of pure sky) are cuts from a recent photo I took. Clearly there is some noise, especially in the second image.
After making some standard editions, such as changing the exposure and adding contrast, the noise becomes more noticeable as you can see in the next two images. Here, the color reduction was already applied, but nothing for the luminance.
And finally, this is what the Darktable noise elimination filter does of this. There are heavy artifacts that are possibly worse than the original noise.
Those devices have a look similar to that of a phone camera when you take an image too dark, so I guess it's not a completely dark problem that I'm here with.
When I tried to replicate something similar in Adobe Lightroom, the noise elimination was much better (see the next two images). Apparently, it is possible to implement a better noise elimination procedure in theory.
I wonder, is there a step that I'm missing in my editing workflow that makes these artifacts are there or is it just an incorrect algorithm that Darktable uses and there's nothing I can do to improve the image?