aiAtmosphereVolume not rendering properly as a PNG using IPR

[cathy_easthope]

Hello. I am rendering a scene with an aiAtmosphereVolume from an area light but although it saves fine as a JPEG from an IPR render, when I try to save as a PNG I get a grey background in that area, almost like it has been turned into an alpha channel. Making an ordinary render takes longer but does not have this problem. What am I doing wrong?
I'm using Arnold 4.2.1 on Maya 2022.

[Stephen.Blair]

IPR does multiple progressive renders, so it should be at least a bit slower than a final render.
For File > Save, did you try changing the Save Options?

[cathy_easthope]

Thank you for the reply Stephen. IPR seems faster than a standard render, which is why I use it.
In the render window Save menu I just use PNG in color managed mode. Render settings are below as well as the PNG and the JPG. I am using a Macbook Pro with Maya 2022 and Arnold 4.2.1. The JPG renders a sky but the PNG just shows grey (shows here as white) where the sky is. If I open it in Photoshop, the grey is an alpha.

[cathy_easthope]

I hope you're still here @Stephen Blair. I did a very simple scene; a single area light with aiAtmosphereVolume and a plane, and PNG or EXR just does not show aiAtmosphereVolume . It doesn't matter if if I use IPR or standard Arnold rendering. On the other hand, JPEG and PSD do. You couldn't make a simpler scene. Is this a known bug?

[Stephen.Blair]

It's not a bug. It depends on what you use to view the png file, and what that viewer does with the alpha.