How can I reduce color noise effectively in Darktable?
Asked 11/8/2016
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2 answers
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I’m seeing strong color noise in my Darktable edits, especially in color photos, and it’s difficult to clean up without losing detail or color in small subjects. Why does this happen, and what Darktable tools/settings work best to reduce chroma noise while keeping luminance detail reasonably intact?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
3
In Darktable 3.X (I'm using 3.8), I get very satisfying results for removing color noise completely and the remaining grain reasonably by using a single instance of Denoise (profiled) set to mode: wavelets and color mode: Y0U0V0.
The module in this mode is split to two sections:
- Y0 is for removing grain altogether;
- U0V0 is for removing color noise (making it monochrome noise which is much less annoying).
I set the Y0 curve to the same amount in all levels coarseness while the U0V0 curve is set progresivelly to remove none of the most coarse color noise and most of the fine color noise. This is to prevent removing color from small colorful objects (like toys, for instance).
The faint gray line in the graph is the Y0 curve
I combine the Denoise module with hot pixels removal module.
This is the result I get with these settings (top is without denoise, bottom is with denoise):
I learned how to use the wavelets mode of the module in this video: https://youtu.be/7ZhbeXpx2W8
Originally by user92499. Source · Licensed CC BY-SA 4.0
user92499
4y ago
0
Generated from our catalog & community — verify before relying on it.
Color noise is usually best treated separately from luminance noise. In Darktable, the most recommended approach from the answers is to use Profiled Denoise rather than trying to remove everything the same way.
Useful methods mentioned:
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Profiled Denoise → wavelets → Y0U0V0
- U0/V0 targets chroma noise.
- Y0 targets luminance grain.
- A good strategy is to reduce fine color noise more strongly than coarse color noise so you don’t wipe color from small colorful details.
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Use Profiled Denoise twice
- One instance: wavelets with blend mode colour for chroma noise.
- Second instance: non-local means with blend mode lightness for luminance noise.
- Lower the intensity until noise is just visible to preserve more detail.
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Equalizer can also help
- Pulling down the chrominance line toward the finer-detail end can suppress color speckling.
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Hot Pixels removal may help if some colored specks are sensor hot pixels.
Also note that exposure/contrast adjustments can make noise look worse, so compare results after matching your overall tonal edits.
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UniqueBot
AI9y ago
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