dark background: remove mottle

[alacant]

Hi everyone
In the old Google NIK Sharpener-Pro-3 suite, there was a ‘structure’ slider. This worked perfectly in removing mottle and blobs from dslr astro-photos’ dark sky background.
Do we have anything in Darktable to mimic this?
Cheers,
Steve

[pphoto]

Got no idea about how that ‘structure’ slider works but for night images I invest more time in denoising and in the hot pixel module.

If I remember there were some threads here about astrophotography.

Some play-RAWs are about night and star photography like these ones:

The screw and the night sky.

Hello everyone, I am new to pixls, and this is my contribution, to improve the edition in this type of photographs, I share this RAW to see your techniques and ways of revealing. If you have doubts, ask, greetings. The screw is the name that has been given to this stone structure, created by the passage of time, is well known and is located in the natural park El Torcal, in Antequera. [_CAL9250] Tornillo y el Cielo.PEF (19.8 MB) Tornillo y el Cielo.xmp (11.9 KB) CC-BY-SA: This file is lice…

My first try at night sky

Taken at the Snowy Range look-out, Almost 13,000 elevation. D3300 18mm 5.6 25 second exposure 3200 ISO [Creative Commons License] This work is licensed under a Creative Commons Attribution 4.0 International License.

[PlayRaw] Milky Way over Geroldsee

You’re probably aware of that, but I think this is the ultimate guide to do nightscapes and astrophotography in FOSS. As a side note, I’ve never used the dark and flat frames steps, and even so could get interesting results, specially considering that my camera is really low profile.

[Play Raw] Nightscape from Orange Free State

Light pollution is there and you can only look at it, sad facial expressions are appropriate . That is second class dark sky, about 20 kilometers South from Heilbron. To get 95mm light pollution filter is very expensive exercise, with holder and adapter comes close to price of lens. If you were thinking that photography is expensive hobby - try astrophotography

[alacant]

Thanks for the links and yeah, some interesting viewing. I’m more deep-sky-with-a-telescope, but some interesting .xmp to see how the experts do it.
Anyway, I’ve a reasonable approximation and perhaps ‘mottle’ was not the correct description. Something like this.
Thanks again.

[elstoc (Chris E)]

Isn’t that the sort of thing the ‘scattering’ parameter (in profiled denoise) is supposed to be used for? Could you try increasing it?

[alacant]

Hi
Yes, it removes the smaller grain but leaves the background with blotches. That in combination with the patch size, seems to get closer to G-NIK’s structure slider.
Still thinking.
Thanks again.

[pphoto]

@alacant

Something like this .

Take a look at the ‘preserve shadows’ parameter in profiled denoise