Incense

by Bart Arondson

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Take the 2-minute tour ×
Photography Stack Exchange is a question and answer site for professional, enthusiast and amateur photographers. It's 100% free, no registration required.

I shot some pictures at night, at ISO 3200, and they are of course extremely noisy. But I want to keep them, and make them as decently looking as I can.

I use Darktable as a workflow software, and it offers four different plugins for denoise. I don't know how any of them works, but even if I knew the underlying principle, I'm not so good at photographic theory to know which one would be best for my pictures. Usually I just pick one at random and leave it at the default presets. But with these extremely noisy pictures, I need stronger denoise.

So I was wondering, should I choose one method of denoise and turn the slider up until I can't stand the blur? Or is it better to use several denoising techniques at once, in the hope that they have different disadvantages which don't stack?

I post the different denoise modules here, maybe some of you can recognize their working principle based on their names and parameters they have.

equalizer

non-local

bilateral

raw

I think that "equalizer" is uncommon, it is a tool for enhancing local contrast for different sizes of structures. It has a "denoise" preset, too. The others are pure denoise tools. The documentation says "raw denoise" comes from dcraw.

share|improve this question

1 Answer 1

As you mention there are several denoise plugins in Darktable, they differs in the algorithm how they will fight noise, speed, artifacts produced, resource usage etc.

denoise (non-local means) - works on luma (lightness noise) and chroma (color noise)

denoise (bilateral filter) - works on each channel (R,G,B noise)

equalizer (exotic wavelets) - i suppose this works on both luma/chroma

rawdenoise - does only work on chroma noise and is faster then the others

I have no deep insight into those algorithms used but the most common used for fighting ISO noise is using raw denoise, i also tend to use normal blending with raw denoise to bring back details using the opacity slider.

share|improve this answer
    
You've provided some insight into how the different denoise work, but haven't answered the question directly - "So I was wondering, should I choose one method of denoise and turn the slider up until I can't stand the blur? Or is it better to use several denoising techniques at once, in the hope that they have different disadvantages which don't stack?" –  rfusca Sep 14 '11 at 15:40

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.