Banding issue

[pscgi]

Hi guys. I've recently started working on animations and I'm constantly encountering some issues that I need to solve. So one of them is banding.

I'm using 32bit EXRs so it's not a matter of not having enough color data but am I right that banding appears when I have very subtle gradients (eg. a white wall well lit from one side and dark on the other side = subtle gradient) and too strong denoiser? I've done some tests and looks like there's banding when a denoiser amount is 1 but when I lower it to eg. 0.8 it seems to be gone. And denoiser radius is always 1, I have never changed that. I'm trying to find a good balance between noise level limit, denoiser amount and rendering time to have a very good quality but without overpaying for render farms.

So could anyone confirm that for sure it's a matter of very subtle gradients + too strong denoiser just to be sure? Thanks! 

[James Vella]

Might be a silly question but is your composition/timeline at least 16bit?

[maru]

So could anyone confirm that for sure it's a matter of very subtle gradients + too strong denoiser just to be sure? Thanks!

This sounds like a very likely cause. I can suggest two things:

1) You can set your main beauty pass to be fully denoised and add a CShading_Beauty render element that will have denoising disabled. This way, for every frame, you will get a denoised and non-denoised version of the same image. You can then use this in your compositing software to blend between the denoised and non-denoised result (e.g. set opacity to 95% or so and check if the issue is resolved).

2) You can manually introduce a bit of noise to your image. It actually works. :) https://www.rene-algesheimer.com/get-rid-of-banding-2/

[pscgi]

Thanks for your answers.

I work in Fusion but yes, everything is set up in 32bit.

Great, that works :) So I'm either gonna use a bit smaller amount for animations like max 0.8-0.9 instead of 1 or I'll just add a bit of noise that hides banding.

So thanks again for your help!