Adobe 1998 VFB icc workflow

[thebeals]

I looked through a variety of forums here, but couldn't find anything that answered my question.

I am trying to understand the best way to view/process exported renders from Vray in the Adobe 98 color space.


Here is my workflow:

I have loaded the icc profile: AdobeRGB1998.icc and also have tried the monitor profile: CG247X(22502106)_CN_Adobe RGB.icc in the Vray's framebuffer based on previous suggestions in others threads here. Both resulted in the same appearance as each other. I am on an Eizo ColorEdge monitor use the Adobe 98 profile which can achieve 99% Adobe 98.

I have rendered one EXR and one PNG from the VFB

Photoshop

When I save an EXR from the VFB, it appears more vibrant in Photoshop than it does in the VFB. I load the EXR with a linear adobe 1998 profile (I have also tried just adobe 1998, but they both appear the same) If I load the EXR back into the VFB, it appears the same as the original render even though it looks different in Photoshop

If I save a PNG from the VFB, it visually appears the same in Photoshop when comparing to what I see in the VFB. If I take a screengrab of the VFB and bring it in to measure against the PNG, it's the same. If I convert the PNG to a 32 bit exr and load back into the VFB, it appears different than the previous renders.

At this point I am guessing that the difference is due to how Vray is baking in the colorspace to the PNG and how Photoshop is applying the color space to the EXR.

I've made sure Photoshop is set to use Adobe 98 and the rendering intent is set to relative colorimetric with Black Point Compensation enabled in both applications.
See attached images for differences

Nuke
I set my viewerProcess to None (only to limit variables and I couldn't find an Adobe 98 profile quickly)
I set my PNG to linear
-I create a colorspace node and place it after the PNG with these parameters:
-in: linear d65 adobe 1998
-out: linear d65 adobe 1998


I set my EXR to linear
-I create a color space node and place it after the exr and set these parameters:
-in: linear d65 sRGB
-out: sRGB D65 Adobe 1998


If I do the above my EXR and PNG match. If I save the images, they also match in Photoshop (although with the wrong gamma due to testing workflow. I would just need to use another colorspace node to convert it back). They also match the PNG that was saved from the VFB.

Questions:

I would imagine that a saved EXR from the VFB would be the most accurate representation and seems to indicate so with the more vibrant colors. I also think this because in order to get it to match the PNG, I had to set the "out" color space to sRGB d65 Adobe 1998, which I think means the saved image is sRGB and not Adobe 98 (correct?)
However, it is odd that it doesn't match the VFB which makes me doubt my assumptions on its accuracy.

1. Does the VFB display the correct appearance of the render when using the adobe RGB.icc profile?
2. If it is accurate, why does the saved EXR not look the same as what is in Photoshop and what is saved out as a PNG?
3. Do I need to do anything to the PNG or EXR to get them to display correctly that I am not doing?

[thebeals]

I forgot to mention another aspect of the EXR workflow .When the EXR is saved from the VFB, there is nothing baked into it and it is a RAW linear file. My assumption is that when viewed in Photoshop using the adobe 98 color space or Nuke, it should be fully accurate, because the application is saying how it should be viewed instead of having the profile baked in. So in my understanding, as I think about it more, is that either that is true and it's the most accurate source of info and Vray's VFB and PNG export does something funny, or the viewing color profile is not being applied correctly in nuke/photoshop and the vray VFB is correct.

On a side not, if I export a 16bit tif, I get the same result as the PNG.

Thoughts on why there is a difference in appearance between the saved exr and the VFB and which is to be trusted?

[thebeals]

This thread was talking about loading the monitor profile in the framebuffer and having things work, but it doesn't seem to work for me
(https://forums.chaosgroup.com/forum/...adobe-rgb-1998)

It seems that most threads are saying the VFB isn't color managed correctly and it will never match photoshop (I could be misunderstanding). There was a suggestion of loading the monitor profile and an adobe 98 color space, but doesn't sound like that is possible. I've also read solutions where you take the EXR and instead of viewing it in adobe 98 in photoshop you view it in sRGB to get the same result which seems backwards and limiting the gamut.

I wonder if what is missing is having control over colorspace, illuminant, and primaries like what exists in Nuke?

I think I want to try and see if the saved PNG from the framebuffer has an adobe98 colorpsace embedded or an sRGB, if it's sRGB than that would confirm (I think) that the VFB is not displaying the render intent correctly.

I am using Vray 3.60.02 in Maya 2017 update 3

Sorry for the rambling, I'm still really confused with the different appearances.

[thebeals]

I have confirmed that the saved PNG is in the sRGB color space while the EXR is in RGB space. This leads me to believe that the VFB is not displaying wider gamut profiles accurately since the VFB matches the output of the PNG. Is this accurate? Can anyone confirm?

[KuDo]

Hello thebeals,

I see this post is already a couple of months old, but I also struggle to get a good colour workflow going.

I am am under the impression that when I want a rendered image to appear in Photoshop as it does in VFB, I have to do a couple of things.
Now I am not saying this is right, but it seems to come close to my desired goal.

As you have said, a PNG coming from the VFB seems to contain sRGB values.

I think the VFB does not translate de RGB values correct to the monitor. So it does output sRGB but does not respect the colour profile that is used by your display.

Therefor I load my display calibration ICC profile in the ICC slot in the VFB. When this is done, it seems to me that a render in the VFB is looking the same as when I open a saved PNG file in Photoshop. You do have to assign a sRGB profile to the opened PNG file. Photoshop then knows it must use the RGB values contained bij the PNG as values defined bij the sRGB colour space.

This matches kind of okay. The problems begins when you would like to preview a image in adobe RGB. This not possible because VFB seems to be sRGB hardcoded.

What I do to work around this is:
- Load the ICC for my display in the VFB.
- Load a LUT that translates from sRGB to Adobe RGB

Maybe this is all totally wrong, but it seems to come really close.

Have you had some progress in creating your workflow?

[thebeals]

Hey KuDo,

That is a really interesting work around. I haven't tried that yet. I don't have a work around currently, I've been waiting for a fix in the meantime. What LUT are you using to translate from sRGB to A98? I'd like to give your workflow a try.

[KuDo]

Hello thebeals,

I have just send you a PM.
Please check if the .cube file is of use to you.
I use that to preview adobe RGB in the VFB.

[matthew999]

KuDo sorry to bump an old tread, i am also having similar issues and desires toget closer in ps to vfb. Do can you also send me the .cube file to translate from srgb to adobe98

thanks in advance

[KuDo]

matthew999 No problem sir,

It seems that the cube file isn't the best solution.

Currently I have an other way of working.

I switch between a couple of different monitor calibration profiles on my Eizo.
for instance. If I need to work towards an adobe RGB colour space I calibrate my screen to that target.
When I need to do stuff for web I calibrate my monitor to sRGB.

Then I don't have to set anything in the Vray frame buffer. My frame buffer will then match my image I have in Photoshop. Provided that you give the image the right colour profile there.

This process differs from how I used to do it. In the old days I calibrated my monitor to the widest gamut I could get on the monitor, but that doesn't seem to be working for my needs. This now is.
Hope this helps!

[matthew999]

KuDo , thank you very much good sir