So, we are doing some movies and need to render to .exr for post. When rendering stills we usually burn in the gamma correction, not using Don’t affect colors. The problem now is that we don’t get the same results with the two methods.
I have gamma/LUT on in the preferences with Input gamma 2.2 and Output 1.0. I tried using Linear multiply with gamma 2.2 first, and then campared it with a render where I use the same settings but switch on “Don’t affect colors” and sRGB in the framebuffer. The result is not the same. What am I doing wrong here?
If you usually “burn” in the gamma, all you need to change is the linear color mapping gamma settings back to 1.0.
Use the sRGB button on the VFB to view the image correctly.
baking the gamma with the save from max is not the same as baking the gamma with save from photoshop. The one mathematically works out things as it should, while the other works out mathematically different. Saving linear exr (with “don’t effect colours” ticked) is the way to go. (ie not baking the gamma at render time save)
AE or Photoshop or Nuke or whatever will interperet your linear (no baked gamma) correctly and display it correctly. From here you can then save your final result. (ie work linear all the way untill you’re ready to output the final product)
If I render an image with gamma 2.2 and Don’t affect colors off, and then take a print screen of the framebuffer, and then compare it to a print screen when rendered with 2.2, don’t affect colors on and sRGB on, they don’t match. Shouldn’t they match?
I am not sure what you are comparing to be honest. But in general “rendered linear with gamma 2.2 burned in, sRGB OFF in the VFB” should match “rendered linear with don’t affect colors ON, sRGB ON in the vfb”
If you are rendering non-linear this will never match a linear rendering as the renderer produces different output (light/shadow propagation, color bleeds etc)
faEke, this problem is normally only if you have some color management problem on your os or software settings, and/or bad calibrated screens, to my knowledge. normally is very much the same. maybe check these things?
stefan
@lllab
Hmm.. we have tried on several pcs at work and at home, the same on everyone, so I don’t think that is the problem.
@dlparisi
I would say slightly different. The sRGB, when compared in after effects, has more contrast than the gamma 2.2 image. And as far as I know, it should be the other way around?
One more problem we have is that we are getting some really strange results with elements when using sRGB. Rawshadow among others is just… totally screwed up.
If you could post some screen grabs of your settings and corresponding renders.
ie. gamma settings in the preferences of max, color mapping settings and VFB.
@glorybound: You are right in sRGB and gamma 2.2 not beeing the same, a manually adjusted curve will definitely be even more off tho. The difference is only very close to 0. sRGB has a linear segment close to 0 (between 0 and 0.055). The rest is gamma 2.2 This is to avoid the curve to be constant 0 for values below 0.
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?
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.
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.
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.
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