How to reduce "color noise" because of color zone module?

I am using Darktable 3.0 on Windows, but I guess it is the same situation on other platform.

Check my sample image, the top one is without color zone applied, the middle one is with color zone applied (to quite extreme extent to demostrate the issue). As you can see the “color noise” is very obvious after I tweak the lightness and saturation, I am not sure it is real color noise or not, because if I turn on “display selection”, the mask and the shape of noises are quite aligned. Plus the picture itself only has ISO 180.

In parametric mask, I can increase feathering radius to smoth the selection, but here I I have no way to do the similar way.

Any suggestion how can I make sky not so noisy?

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I wouldn’t call that color noise, but halos from the color zone module. Have you tried not using a parametric mask?

I tried, but it is very difficult to separate sky from mountain. The masks available from this module are L, a, b, C, h. I tried combinations of them but still no luck.

  • Then try to combine parametric mask with drawn mask. For example, select only the sky with drawn mask (path tool).

  • You can also blur the parametric mask.

  • Choose “chroma (use on 1st instance)” preset for denoise (profiled) module

  • Offer us the picture as a “Playraw” (or provide us RAW file here) and we will find a suitable solution for you :sunglasses:

Hi Boris

Here is my raw file and basic editing xmp file https://ln2.sync.com/dl/6f7333480/kghje9bz-rvtaa3i2-tpxxpgqi-a8ebaz79. Please show me your xmp file if you manage to smooth the sky and meanwhile it is also darkened.

Thanks

P.S I do enjoy your YouTube channel of editing moment.

hi @hardywang

here are two versions:

without haze removal

DSC_5025.NEF.xmp (8,1 KB)

and with haze removal

DSC_5025_01.NEF.xmp (11,4 KB)

i hope you could open both files as i am using the development version of darktable (3.1.0)

nice shot BTW!

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Hi Boris,

Yes, I can import them with some warning. So basically you leverage denoise module to smooth the cloud, is it correct?

And meanwhile you used color balance module to boost saturation and contrast. Can I ask what is the benefit to use this module instead of velvia or contrast equalizer?

Great work, thanks!

Yes. Denoise module is well suited for this. In 2.6 and now again in 3.1 version of darktable, preset “chroma (use on 1st instance)” gives excellent results. In your example, I have tested new denoise method of darktable and it is just as good.

Color balance module is part of the new linear RGB workflow and offers a lot of improvement possibilities in one instance, e.g. setting contrast with variable focal point (fulcrum), saturation, color and brightness corrections in separate brightness areas of the image etc. A very powerful module that can save you a lot of work.

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Thanks a lot for your explanation.

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