Light banding in render but not in Arnold renderview.

[Anonymous]

So i'm trying to use aiVolumeScattering for the lighting in my scene but whenever I render there is banding present. This is especially confusing to me because in the Arnold render view there is no such banding present. I have tried everything I could think of and it has proven to be very frustrating. 

Photo: https://i.imgur.com/Ju1kss4.png (Arnold renderview left).

[mspeer]

Hi!

Arnold Render View may use some sort of dithering.

Read more about banding and dithering here:

https://forums.autodesk.com/t5/maya-shading-lighting-and/banding-in-render-arnold/td-p/6669473

[Anonymous]

Thanks, but not much I have been able to find elsewhere on the internet has helped me understand this issue so far, I am looking for a more specific method of eliminating this banding.

[mspeer]

Hi!

Think about an image with a gradient from left to right with black to white and your image (or monitor) can only display 8 different Colors.

That's banding, you will get 8 unique stripes. The more colors your image (or display) has, the less banding will occur.

So color resolution of image and monitor just has to be high enough.

Save as 32-bit EXR and there will be no banding in the image.

[Anonymous]

Thank you so much and this clears a lot up, but I am having some issues figuring out how to save an exr as 32 bit.

[mspeer]

Hi!

An EXR uses 32-bit as default (sometimes 16-bit but even this is more than enough).

[Anonymous]

It has now become more apparent to me that the image being 32-bit isn't helping, I will attach a photo of my render, Arnold renderview, and render setting below.

[kollig]

Have you checked the saved exr with another program? And check it on different monitor. I have two monitors here, where one shows banding artifacts in some cases, but the second one shows a clean image.

My guess is that the linear to sRGB conversion of the Render View is the reason for the banding artifacts. I don't think that the banding is related to volume scattering. The region is very dark, where gamma correction increases brightness differences very much.

[mspeer]

Hi!

1. A .png (8-bit) is not a 32-bit EXR so how should i see that 32-bit EXR does not help?

2. Screenshot are .png (8-bit), they are also only usable if Render View is perfectly scaled 1:1 (not always true, even if you hit the right button).

3. What resolution is your monitor, i would guess it's also only 8-bit per Color Channel?

[Anonymous]

Here is the EXR, my monitors are both 1920x1080.

EXR dl: https://drive.google.com/file/d/0B2u230hxz0RNdWtTWFkzZkl2UU0/view?usp=sharing

[kollig]

I've looked at the exr on different displays. Depending on the display I see banding on the floor, the upper part is just noisy.

Since the banding depends on the display, it moves when increasing the exposure, and there are no jumps in the pixel values, I would say, that there is no banding in the data, but is due to display incapabilities (only 8 bit per channel, quality of display).

[mspeer · Accepted solution]

Hi!

@kollig is right.

There is plenty of information in your image, so the monitor is your limitation. Just make the image brighter and the banding on the floor disappears.

That's a limitation of current displays and has nothing to do with the renderer. You will see this also often in TV, especially in dark areas of the image.

You can try to do some dithering but this will increase noise.

Finally, there is no error in Maya or Arnold, it's a limitation of current displays and display formats.