VFB saving out images with ICC-profile active

[sicknifikant]

Hi,

I reported a bug about VRay Next not saving out images correctly when an ICC profile is active in the VFB. That was three months ago.
They said is was added to the bug tracker.

Great to know. But when will this be addressed?

I bought NEXT to actually be able to use it. But ATM I'm constantly forced to some really silly workarounds especially when clients ask to change something on images I created earlier with VRay 3.6.
This really gives me headaches and I'm starting to feel pissed because NEXT could be a great release but actually for me it just sucks.
I'm just about to deinstall and go back to 3.6.

Being able to save out images correctly is like the most important thing a render engine should be capable of. Come on guys fix this!


Sorry for the rant.

[vladimir.nedev]

Sorry, I cannot find an issue related to a regression with ICC logged in the last few months.

Can you link the original forum thread or describe what's the regression compared to V-Ray 3.6 ?

Greetings,
Vladimir Nedev

[vladimir.nedev]

I will answer your private message here, so other users searching for ICC issues can see these answers.
(And also because the private message reply dialog is super inconvenient.)

1. As soon as you activate it once in VFB you can not go back anymore. The whole images is way darker (like image below) when you deactivate it again. This was already in 3.6

This is more of an UI issue. When you deactivate ICC, you no longer have the sRGB correction applied.
You have to click and hold on the ICC button in the bottom tool-bar and choose sRGB from the menu that appears.
Then click on it to activate it. See attached screen-shot.

2. As soon as ICC is active, trying to adjust things while preview is active is almost impossible. Modo becomes extremely laggy. Ticking off ICC helps for the moment but then you can't see the changes very good because image is way too dark without ICC.

We do have a performance issue there, which is currently logged.
Unlike most of the other color corrections, the ICC correction is not multi-threaded which is one of the reasons for the extra lag you experience.
The ICC correction is also applied by a third party open source library and I am not sure how well optimized that is.

I can't give a time-frame when we can enable multi-threading on the ICC correction.

3. In NEXT saving out images withh ICC profile active results in way too dark images. Only way I can save images ATM is EXR because it doesn't take ICC into account. All the other formats are useless.

This is the only regression compared to V-Ray 3.6.
Issue 1. and 2. are present there as well.

Honestly, looking at the code, I am not sure how this worked in 3.6.
The LUT/OCIO/ICC corrections are supposed to be applied only for display purposes.
Because of popular demand, we've added options to the LUT and OCIO roll-outs (in the latest nightly builds) to apply them when saving to a file as well.
However, we don't have this option for ICC.

For now, the only work around is to click on the VFB image, press Ctrl+C to copy it and then paste it in an image editor.
The copy will have every correction in the VFB applied, including ICC.

I will see if we can add an option for saving ICC to file as well.

Greetings,
Vladimir Nedev

[sicknifikant]

Hi Vladimir,

thank you very much for your thorough explanation.
The described work around is very helpful and should be ok for the time being...

Working in VFB in sRGB mode is a relief because finally I can develop my projects with preview running as I could with modo native renderer.

[vladimir.nedev]

2. As soon as ICC is active, trying to adjust things while preview is active is almost impossible. Modo becomes extremely laggy. Ticking off ICC helps for the moment but then you can't see the changes very good because image is way too dark without ICC.

Turns out enabling multi-threaded processing for the ICC correction is easy to implement.
So this change will be in the 4.12.02 and 4.20.90 nightly builds from 2019.10.24 (tomorrow).
On my 8 core (16 thread) Ryzen there is a significant reduction in the amount of lag with ICC enabled.

3. In NEXT saving out images withh ICC profile active results in way too dark images. Only way I can save images ATM is EXR because it doesn't take ICC into account. All the other formats are useless.

Turns out I was wrong. This is indeed a regression compared to 3.6.
So the nightly builds will have it fix, i.e. saving images to disk with ICC enabled should work the same as in V-Ray 3.6.

The V-Ray Next for Modo nightly builds are here : https://nightlies.chaosgroup.com/mai...y4modo/nightly
Please test with the 2019.10.24 build (which will be there tomorrow) to confirm the issues are fixed.
If you don't have access, you have to write an e-mail to support@chaosgroup.com to request it.

Greetings,
Vladimir Nedev

[sicknifikant]

Great news. Thank you very much for solving this.
I'll test it tomorrow.

[sicknifikant]

Hi Vladimir,

did some tests today and as far as I can see everything works perfectly fine.
Good performance, no need to temporarly switch off ICC and saving images works as well.

Great job. Thank you!!

[vladimir.nedev]

Great.
Thanks for testing.

Greetings,
Vladimir Nedev