Environment brighter with Alpha channel enabled

[richardwright]

Running latest version of OctaneRender 2019 for Blender 2.8 free tier.

If I enable Alpha channel in the kernal settings the hdr sky gets brighter.
Doesn't change the lighting of the other items in the scene.
Only affects the preview renders not the F12 render.

Tried the same settings in Lightwave Octane 4 and it doesn't do this.

[J.C]

Can you share the blend file?

[richardwright]

The sky is an HDR in the original.
I swapped it for a daylight environment which does the same on my machine at least.

[J.C]

Disable "Keep environment" in kernel settings to solve the issue.

[richardwright]

But then the sky disappears.
I really don't want to setup lighting and materials with a black sky.

In Standalone I have both Alpha Channel and Keep Environment enabled and the sky isn't brighter.
The same in Octane for Lightwave.

[J.C]

Looks like a bug to me. Please report this in bugs section.

[linograndiotoy]

That's definitely a bug.

[Dreviou]

Hmm, any solution to that issue? Got the same problem with a newest 2020 build. Alpha checked, exposure brighter.

Edit: I've done some tests. Enabling Alpha Channel brightnes only a viewport rendering. Output renders are being saved without additional exposure. So I guess the only workaround for now is to just enable alpha channel just before final rendering. Still, should be solved somehow...

[linograndiotoy]

My feeling is you need to tweak your color space options in Blender and Octane. Can you please share a simple scene showing the issue?