Corona 13 Color management problem

[v.p.vlasenko]

Hi, the image saved from a VFB looks different when color management is set to OCIO.

Display/View-Transform is enabled (obviously without it images are dark).

So, if max saves images or from native max VFB - all ok, but if I save it from VFB 2.0 or 1.0 - looks wrong. It seems like a few months ago all worked fine - I worked on a project in March and everything was fine (or I didn't notice the difference that time...)
The next one is probably max problem, but just to ask. Same settings:
2024 renderoutput - save png and exr exactly as in VFB.
2025 renderoutput - save png but not exr, exr is dark, it seems like it skips conversion.
Is it max problem or can be something you can fix?

Latest Corona daily.

[Aram Avetisyan]

While I was writing this reply, the results started changing, so I will be making more tests.

I can confirm partly what you wrote, but in the exact manner as you describe.
In the meantime, which application are you using for previewing EXR files?

[v.p.vlasenko]

Fusion

To clarify:
saving from VFB works wrong for png and exr (and I guess other formats)
saving from renderoutput (native max) works for png and exr in 2024, but in 2025 it's working only for png, but not exr.

[Aram Avetisyan]

I think I have finished the tests. The whole topic is technical and complicated, and so were the tests, and details matter here.

Please be more detailed and attach all relevant information when sharing tests results - the output conversion (which may be set to automatic, and change from format to format, from Max version to version too) matters here. So here are the results with Corona 12 HF1 (nothing should have changed to color management since then), Max 2024 and 2025:

• PNG (low dynamic range) output from Corona VFB and Max VFB differ, if there is display/view transformation set (default) for output. Confirmed in a simple scene, for Max 2024 and 2025.
• PNG output from Corona VFB and Max VFB are the same, if there is no output conversion set. True for Max 2024 and 2025
• EXR (high dynamic range) output from Corona VFB and Max VFB, without output conversion, are identical for Max 2024 and 2025.
• EXR output from Corona VFB and Max VFB, if there is display/view transformation set (default) for output, will differ only for Max 2025 - now this is the tricky part:

Diplay/view/color transformation-conversions should be ignored for high dynamic range outputs (they should be set by viewing application, e.g. VFBs, and should not alter the original high dynamic range render when saved). Max 2024 did not ignore output conversion (bug) for high dynamic range outputs, and apparently so did and currently does Corona VFB.
But Max 2025 "fixed" it - saving out EXR with (1) or without (2) output conversion, from Max VFB, results to exact same image (correct). Saving EXR from Corona VFB, without output conversion (3), will be correct, as in 1 == 2 == 3. But when saving EXR with explicitly set output conversion, from Corona VFB, will take the conversion settings into consideration and result in a different output.

[v.p.vlasenko]

Hi,

• PNG (low dynamic range) output from Corona VFB and Max VFB differ, if there is display/view transformation set (default) for output. Confirmed in a simple scene, for Max 2024 and 2025.

that's what I'm talking about

EXR - my bad, I just found that in What's New in 3ds Max 2025.

But when saving EXR with explicitly set output conversion, from Corona VFB, will take the conversion settings into consideration and result in a different output.

Just checked - yep, working. Same image in vfb and exr.

So only the low dynamic range problem is left.
To confirm that we talking about the same thing I'm attaching images - settings and outputs. The left side is 3dsmax output/copy from VFB and the right side is saved from the VFB save button.