Vray Luts look wrong

[Donfarese]

I'm sure this is something I'm doing wrong, but when I add Luts to other renderers I get what I expect and similar results. But when I add the same Luts to Vray I get very odd results. I attached an image showing the issue with just one Lut and with Corona since Chaos owns both. See what the Lut does to the Vray render compared to what it does to the Corona render. This Lut happens to use log space, if that matters.

[Donfarese]

This was supposed to go in vray 3dsmax general. Devs can you please move?

[yavor.rubenov]

Hello,

From the screenshot I see you selected 'Work in Log' for the LUT - maybe the LUT is actually for sRGB ?

Best regards,
Yavor

[Muhammed_Hamed]

Hey Donfarese

I moved the thread as requested

Like what Yavor said, this looks like a Gamma issue. You can upload the LUT and EXR for us if possible, it will be helpful

Best,
Muhammed

[Donfarese]

Hi Muhammed, thanks for moving the thread to the right place. So the LUT uses a Log Space. I created a new simplified version of the test using a LUT that doesn't need LOG space and everyone has so you can try yourself. Attached is the image of the results, and LUT. Below is the name of the LUT I used.

LC3DL_Kodak2383_log2hd_ConstLmap.cube

[sirio76]

I’ve experienced the same issue in the past but I think the LUT works in a weird way in Corona, I mean I can get consistent results using the same LUT in both Vray, Nuke and PS but in Corona they works differently.

[Donfarese]

I’ve experienced the same issue in the past but I think the LUT works in a weird way in Corona, I mean I can get consistent results using the same LUT in both Vray, Nuke and PS but in Corona they works differently.

Are you sure you don't have that backwards? Attached is an example of the same LUT applied in Photoshop and the V-Ray with LUT now matches Corona with LUT from VFB exactly. I have always gotten correct results in Corona.

[Donfarese]

Anyone have any thoughts on this?

[Dart_Design]

Anyone have any thoughts on this?

Hello. Adan Martin (3DCollective) has his luts always in 2 versions: for vray in linear and for corona in srgb. It can be your case.

[hermit.crab]

I just tested this and it seems that results in Nuke are similar to those of V-Ray (linear color in); while the Corona results are similar to PS. What Dart_Design said could be it, since neither PS nor Corona color input options for LUTs. Otherwise, I've asked the Corona team if they can clarify the case.

[Donfarese]

Thanks for looking into this guys! V-Ray seems to have quite a few input options for LUTs, I'm surprised it doesn't have an input option that matches Corona. I would think since you guys own both and many people use both for even the same projects and need to match the look this would be a must have feature. Can this be added if there is no way now to do it?

[Donfarese]

Hey guys, any answer to my last question?

[hermit.crab]

We found what's the cause of the issue - the order in which color corrections are applied. In V-Ray, you need to set your Display Correction as "None" and the lookup table to "Work in sRGB". This way the results between V-Ray and Corona are identical.

[Donfarese]

We found what's the cause of the issue - the order in which color corrections are applied. In V-Ray, you need to set your Display Correction as "None" and the lookup table to "Work in sRGB". This way the results between V-Ray and Corona are identical.

Yes, that was it! Thank you for looking into this, this is really helpful for people that want to work with both renderers.

[kosso_olli]

We found what's the cause of the issue - the order in which color corrections are applied. In V-Ray, you need to set your Display Correction as "None" and the lookup table to "Work in sRGB". This way the results between V-Ray and Corona are identical.

This only works as long as you do not save the image. The written output is totally messed up with LUT baked into the image.