Noise Reduction with the Compositor

Clean those noisy Cycles renders in post!

The eternal struggle between artist and render engine is finding the balance between noise and render time. This is certainly true for Blender’s Cycles engine. Wouldn’t it be nice if we could clean that pesky noise in after the fact with the Compositor? Yes. And we can!

In this quick tip, Gleb walks us through the process of rendering with low samples, separating the image into passes, and putting it back together in compositing with significant noise reduction. This can be easily setup thanks to the bºwide Node Pack which includes a pre-made “PassCombineDenoiser” node group.

comparison

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29 Responses to “Noise Reduction with the Compositor”
    • Posts: 12
      anarchymedes says:

      Hi Gleb, if your question is addressed to me, then here is as much detail as can go here, without the actual screenshots: I ended up creating a node group that included a Difference Key node (one of the matte nodes) in order to obtain a mask that would give me only the noise, and then use it (the mask) as a factor for a mix node that combined the original image with the output of a Translate node. In short, this whole setup worked to replace the ‘noise’ pixels with the neighbouring ones, but leave the rest of the image intact. Of course, the tolerance and the falloff of the Difference Key node, as well as the distance of the shift had to be found by trial and error, and I actually ended up using a chain of these groups to remove the noise of similar, but subtly different colour. The advantage of this method is that it does not introduce any additional blur to the areas of the image that aren’t very noisy. Besides, it can be applied to a render from a different .blend file — or any image, for that matter. The disadvantages, as I see them, are lots of fiddling it requires, a lot of memory these image copies will consume, plus the need for the noise to be of more or less the same colour.

  1. Posts: 7
    Uwe says:

    Great! Very helpful for me …

  2. Posts: 29
    tainted-luv says:

    using it, image not coming out on the other side. Plugged everything in the way the tut showed…Black image.

  3. Posts: 6
    jason han says:

    Gleb
    Can you share the actual .blend file with the entire node setup included?
    I tried downloading the files and it only has the video tutorial and no .blend file from the tutorial.
    Thanks.

  4. Posts: 1
    einsteinsci says:

    Not working for me. Using Blender 2.7, the only difference in implementation is that I turned on emit. Instead of a rendering I get a black screen. Turning off emit had no effect.

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