Linear AdobeRGB profile for VFB

[Art48]

Hi,

I notice that the VFB uses sRGB but we are using AdobeRGB in our postproduction (Photoshop) pipeline.
So the images actually saved from the VFB sometimes have differences in saturations/brightnes. This is no big deal although I would prefer having the exact same output.

So I thought - if you theoretically load a linear AdobeRGB LUT instead of using the sRGB button that should work right? Thing is: Where do I get a linear AdobeRGB profile? Or am I thinking something wrong?

[Morne]

All the profiles on your PC is saved here: C:\Windows\System32\spool\drivers\color
Renaming a icm to icc seem to work fine for some monitor profiles.
You'll need to load your monitor profile into the ICC and then you'll need a way to convert the AdobeRGB to a cube file and then load that into the LUT.

If you have your monitor calibrated and you don't load it into the VFB, it is unlikely that you will ever get a match to what you see in PS (with and without the AdobeRGB in PS). This is because PS automatically reads the monitor profile from Windows, but the VFB has to be told to do so

[Art48]

Oh, okay then. Uhm... so I basically need 2 Profiles: My Monitor profile as ICC and AdobeRGB as LUT? I see the AdobeRGB1998 there, as ICC, but no linear one.

[DaveKW]

The whole topic of monitor profiles and where/how to apply them in PS/VRay is still a complete unknown to me. Is there any info out there that demystifies the whole process?

[Morne]

The whole topic of monitor profiles and where/how to apply them in PS/VRay is still a complete unknown to me. Is there any info out there that demystifies the whole process?

If you have a callibrated monitor, things are for the most part "automated" in PS and you don't have to change or assign anything. It just works. You can still apply AdobeRGB etc if you like.
The whole issue with this whole thing comes in because Max has not yet implemented any kind of color profiles, meaning it doesn't read it from Windows and just ignores whatever profiles are set in Windows. Max always just assume you have sRGB profle and that's it. The ChaosGroup guys had to overcome this shortcoming of Max and therefore added the ability to load LUTs and ICCs into the VFB.

@David on a slightly different note, have you guys found all the new people yet that you wanted for the Westby studio?

[DaveKW]

If you have a callibrated monitor, things are for the most part "automated" in PS and you don't have to change or assign anything. It just works. You can still apply AdobeRGB etc if you like.
The whole issue with this whole thing comes in because Max has not yet implemented any kind of color profiles, meaning it doesn't read it from Windows and just ignores whatever profiles are set in Windows. Max always just assume you have sRGB profle and that's it. The ChaosGroup guys had to overcome this shortcoming of Max and therefore added the ability to load LUTs and ICCs into the VFB.

@David on a slightly different note, have you guys found all the new people yet that you wanted for the Westby studio?

So if Windows uses the profile for things to appear 'correct', do I still need to assign that profile in PS? Because unless that profile is embedded in the image, it won't look the same for other people viewing it. But then if it's embedded am I then doubling up in PS when I assign that profile seeing as Windows is already changing the display? I really do need an ELI5 version

As far as the Westby positions go, I'm not sure what's happening as it's all dealt with by HR.

[Morne]

No monitor callibration is for that specific monitor(s) on that pc only and it is only a display thing. Basically the color profile created from the hardware callibration device tells Windows to map the colours a certain way because you monitor is capable of displaying such and such colors. Most apps nowdays can read this profile from Windows, and therefore displays the colors "correctly" like it was meant to be viewed. You never embed this monitor profile into any image because that monitor profile is only valid for your pc and your monitor(s). Some apps DON'T read the monitor profile from Windows and therefore will fall back to just using sRGB. Max is an example. Last time I checked, Skype is another culprit that DOESNT read the profile.

You don't need to set the monitor profile into PS as PS is smart enough to read it from Windows. Even though your PS working space may be set to sRGB, it 1st gets punched through the monitor profile to arrive at an sRGB appropriate for your monitor. If you don't have a monitor profile then Windows will be set to sRGB by default. PS will then pucnh it's color space of sRGB through the Windows sRGB colour space and because they're the same, no mapping or shifting will happen and therefore the color will be slightly off.

That's why you need to load the monitor profile into the VFB. Here's from the official help pages:
http://docs.chaosgroup.com/display/V...orrections-ICC

Normally you would specify the ICC file for your calibrated monitor here. Programs like PhotoShop display images using your (primary) monitor ICC profile automatically. However (at least for the moment), 3ds Max is not a color-managed application and you must manually load the monitor ICC profile into the V-Ray frame buffer in order to match the appearance of your images in PhotoShop.

It can get tricky when you have more than 1 monitor since then you need to callibrate both. They will never be exact same even if they came out the factory one after another. So you will end up with a profile for EACH monitor. Then depending on which monitor you use mostly to view your VFB, that's the one for which you need to load the profile. If you then move the VFB over to the other monitor, the colors will be "incorrect" and you need to load the profile for THAT monitor. Same thing in PS then. You need to view the VFB and PS on the SAME monitor to make a comparison.

Hopefully that makes sense?

Basically the whole callibration thing is because "full" red for example on one monitor will look like 255,0,0 but on another monitor full red may look like 250,5,0 (to your eyes, not actual RGB values). So then the hardware callibration device goes and reads the red from the monitor and goes, hmmm the red is slighlty off so probably the monitor can't display red correctly. To compensate, let's shift the profile for red up 5,-5,0 to compensate so we can arrive at 255,0,0. Take note this last bit I'm not talking actual RGB colours, I'm just trying to explain in a simple way how and why we need callibration... This compesnation and shift in colours is what happens when you view images with or without the profile in VFB vs PS for example

[Art48]

Good explanation, yet I am still a little confused.
When I calibrate my monitor, the screen as a whole gets calibrated, not specific windows only. So when the VFB appears it gets displayed the same (calibrated) as any other window, too. I'm sorry, I feel really dumb here, but then maybe this is not the right place to discuss it?

[Morne]

Good explanation, yet I am still a little confused.
When I calibrate my monitor, the screen as a whole gets calibrated, not specific windows only. So when the VFB appears it gets displayed the same (calibrated) as any other window, too. I'm sorry, I feel really dumb here, but then maybe this is not the right place to discuss it?

The whole of "Windows" get callibrated yes. But Windows then tells each app to read the profile. But not all apps understand that Windows is callibrated and therefore don't even bother checking or listening so they basically say to Windows, bugger you Windows I'm old fashioned and I don't even know what profiles are so I will just display things how ever I want, which ends up being default sRGB. Max is like that and thats why we need to "force" a profile into the VFB

[Art48]

Ah okay now I got it, thank you very much for that in-depth explanation!

[Lupaz]

which ends up being default sRGB. Max is like that and thats why we need to "force" a profile into the VFB

First of, thanks Morne.

Does this mean that it makes no sense to work in Adobe RGB in PS?
I mean, if the colors come out by default as sRGB from Max, that means that the gamut is already clamped when it gets to photoshop. Even if I convert to Adobe RGB in VFB or PS, the colors are all set.

Is this correct?

[Art48]

Nah, as I understood is the information is all there, it's just a matter of how to interpret that information. What you see in the VFB is the information interpreted/shown in sRGB.
When you nopen the saved EXR file in PS and set it to AdobeRGB, it gets treated/Shown as Adobe RGB. There is nothing lost/baked inside of 3ds max.