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I have been fighting with the noise reduction of the following image in darktable:

enter image description here enter image description here enter image description here

I used this website: https://tomassobekphotography.co.nz/articles/reducing-noise-in-Darktable.php

and tried all the methods available in Darktable, which seems to be the best of the open source software choice.

Is there any better solution to do this? My images have been taken with ISO 1600 and 2500. Why is my RAW noisier than jpeg?

The answers here:

don't solve my problem, as I have to pay for those apps. On the other hand, The RawTherapee is quite poor at it, as per: Why doesn't noise reduction have any effect in Rawtherapee?

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    \$\begingroup\$ Despite the linked question, I've found that RawTherapee often has better results in noise reduction than Darktable does, especially for high ISO noise. However, your particular image, because it's so dark to begin with, is likely to be very difficult to denoise to anything resembling clarity. The darkness of the image leads to a very low signal-to-noise ratio. Perhaps converting it to grayscale with some color filter will help, or perhaps not. \$\endgroup\$
    – twalberg
    Feb 24, 2020 at 21:01
  • \$\begingroup\$ What camera did you use to take the picture? \$\endgroup\$
    – Michael C
    Feb 24, 2020 at 23:02
  • \$\begingroup\$ Nikon D5300. How about if I rise the EV for this image? \$\endgroup\$
    – Geographos
    Feb 25, 2020 at 10:24
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    \$\begingroup\$ What happens if you first open it in ViewNX-i then export as TIF for further work? \$\endgroup\$
    – Tetsujin
    Feb 25, 2020 at 11:55
  • \$\begingroup\$ Once I open in ViewNX it looks far better than in Darktable. Even in the RAW cases. I haven't tried yet an option with TIFF export. \$\endgroup\$
    – Geographos
    Feb 25, 2020 at 12:19

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Why my RAW is noisier than Jpeg?

Because the JPEG created by your camera included the noise reduction contained in the camera's raw processing engine. When you work with the raw file in another application, none of the in-camera processing used to create the JPEG is used by your external raw processing application. It uses its own noise reduction algorithms based on the settings you have selected within that application.

If your camera's manufacturer has their own raw processing application, using it may include noise reduction very similar to the camera's internal JPEG engine.

The reason your image is so noisy to begin with is because it was exposed very dark, so there's not much signal (light) to overcome the noise. Thus you have a low signal-to-noise ratio.

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On the other hand, The RawTherapee is quite poor at it, as per: Why doesn't noise reduction have any effect in Rawtherapee?

Uh, you have read the accepted answer? Noise reduction is only visible at 1:1 scale, like after typing "z". Rawtherapee offers global noise reduction (try the difference between "conservative" and "aggressive" settings as well) up to terrifying degrees. However, the image enhancement tab also has Wavelet-based settings which allows you to tune noise reduction at various image scales, like pushing it harder for small-scale noise, or focusing on reduction at larger viewing scales. In particular in connection with wavelet-based contrast enhancement, that can result in a reasonable appearance in spite of high contrast processing.

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