Don't affect colors problem

[glorybound]

my question is why, are we fighting this? Is it because of legacy issues? I never had to worry about it in Accurender, or Lightscape, or even Revit. Would a good CRT monitor solve all these issues?

[instinct]

I am not fighting it tho many people seem to. The Problem is sRGB or any non linear colour space altogether. It was introduced to compensate for technical limitations. These limitations are long gone, the compensations sadly are not. If you are renderling linear, saving linear and working linear in post using a display lookup matching your output device (= Monitor) then there is no fighting in my eyes. It would be interesting to see images of issues and the corresponding settings to dissect the issue.

Regards,
Thorsten

[glorybound]

The first exterior I did using V-Ray (see below), about 3 years ago, turned out good. The more I read on gamma 2.2, the worse things got. About 6 months ago I dropped all the science and started rendering again, and things started to improve for me . My workflow is now: if it is to dark lighten it, and If it is to light darken it.



Above image: I am not sure why I am showing so much pavement and the entrance shouldn't probably be in the shadow - I would probably change that if I had to do it over again.

[fAEkE]

If you don't plan to do any editing, then it is that easy.

[instinct]

There is not much to read about gamma 2.2...actually you want to go linear and NOT gamma 2.2 (yes a tad picky i know )

We're doing massive amounts of editing and post. Doing a lot of post is one of the main reasons we went linear, because quite a bunch of things we do only works in linear colorspace. Anyways, if you feel you are producing better images without, then don't bother using it. The result is what counts in the end. Linear might be more correct (in different ways), but if it looks bad that won't help convincing the client. You have to work differently, light differently in linear. You need to get used to having "less blacks" as most artists put it for example.

[glorybound]

okay, not another gamma thread!

My understanding is linear is gamma independent. If I keep everything the same, in every application, I am working linear.

[instinct]

Not really. You can also work sRGB in all applications and keep that the same...but then you are working sRGB, not linear.

[bob-cat]

.....mmmm, is sRGB the new Linear
how about we start a new thread - "Linear vs sRGB"

[Deflaminis]

I had this problem just recently, hopefully my solution can help you. I usually put the max gamma at 2.2, input gamma at 2.2, output at 1.0, and the vray gamma at 2.2 with Don't affect colors checked. Works great for my purposes but this color change problem after rendering was a major problem for me and was really changing the entire gamut making the renders not even close to what I had in max.

Turns out it was unrelated to max or vray, but the problem was that for some reason my monitor had an incorrect color profile attached to it. (It was for the 2nd monitor but somehow applied to the first, which is a different brand.) It was working fine for months then all of a sudden... bam looks like crap. I never even manually installed a profile. So things would look right in max but when windows or photoshop was interpreting color it was hosed. Even when printscreening as you mentioned that you tried.

Drove me NUTS trying to fix it. In the end this is what I did:
Right click on the Desktop (Win 7)
Click "Screen Resolution"
Select the proper monitor if you have more than 1
Click "Advanced settings in the lower right side of the window
Click "Color Management" tab
Click "Color Management"
Check in devices to see if you have a color profile attached to that monitor. For me, removing the profile Cintiq24ux solved my problem. I then applied it to the 2nd monitor instead and everything works great on both now.

Took me forever to figure this out, but once I did the colors matched exactly out of windows and out of vray.

Also it would make sense if this is happening on multiple computers at work because they were most likely imaged or ghosted by IT and so they'd all have the same issue. (Potentially.) How that made it to home... not so sure. To be honest I never installed a profile at all yet I had one assigned to the wrong monitor. Happened about 2 weeks ago sort of randomly, so maybe a windows update or a driver update did something to move those values around. Otherwise I can't imagine what it would be, but it fixed my problem right up.

[fAEkE]

Thanks for the reply Deflaminis. This problem of years was that what you saw in the vray framebuffer did not look like the .exr that you opened in photoshop or after effects?

Thats not the problem we are having tho. What I refered to is that the result when using "Don't affect colors" and sRGB OFF is NOT the same as if these options or ON. They should be the same, yes?

[add101]

ok, disregard this post. i thought gamma 1.0 with 'don't affect colors' produced less noise, but it's actually gamma 2.2 with 'don't affect colors'.

Hi fAEkE, i think it would help if you posted the settings you're using, and the examples.
From your last post i read that you're changing don't affect colours and and srgb, but are you changing the gamma setting in vray as well?
I think the gamma in the color mapping rollout should be 1.0 and 'don't affect colours' on and srgb in frame buffer if you want to render out a linear exr. (along with gamma settings in the max preferences dialog).
rather than gamma 2.2 to burn gamma in to 8 bit images- with 'don't affect colours' off, and srgb in frambeuffer off.

LWF is confusing because there are so many options, and different ways to implement it.

Ok, I've just done a quick test, and no noticeable difference between the two on my side. Did you change the gamma in v-ray color mapping to 1.0 for linear/un-(inverse)gamma-corrected output?

If it was a slight difference between photoshop and vfb the monitor profile thing could be the cause, but if it's all in the vfb must be something else.

[fAEkE]

It's all in the VFB. And we have tried all kind of different settings regarding gamma. Gamma 1, 2.2, 5, 10, 500.. Gamma/LUT On, Off, different settings...

The two methods donät produce the same result for us, ever.

[add101]

Strange. Might help to post your gamma settings in max and v-ray and test images.

[add101]

Ok, I said gamma 1.0 in earlier post, but i see that in previous files I've used gamma 2.2 which produces less noise. With 'don't affect colours' it keeps image gamma of 1.0.

Can be a confusing topic! Cool when it works but sucks when it doesn't.

I do notice a slight difference when i overlay them in photoshop and adjust opacity, the linear image with srgb correction in vfb is a bit darker. Very minimal on this example though.

[fAEkE]

It will be more clear if you use one area light, no Skylight and only 8 subdivs on the light, try it out.