Denoise after render

[davetwo]

 I ave some shots that really need denoising in some areas but have other fine detail that is lost if I denoise. So id like to render once, denoise a copy and then comp it with the un-denoised version. Is this possible? From CXR perhaps?

[lollolo]

Sure. Activate multipass and there under shading you should see VirtualBeauty. Choose VirtualBeauty two times, first with denoising strength 100% and another with 0%.
So you get a denoised and undenoised version of your render.
You can mix them in post.

[TomG]

You could even have 3 (or 4, etc) VirtualBeauty elements, e.g. with 0, 0.6, and 1 denoise values, if you want an even finer split of areas that get denoised by different amounts :)

[davetwo]

Nice! Hadn't thought about separate beauty passes