Disable Max Gamma Correction and use VRay's LWF button?

[Deflaminis]

It is true that there are several possible ways to do a linear workflow. They can all be correct.

Nope, they are all correct.

How do you know that? I don't know of a render engine that can guess 100% what you want to do. Maxwell tries to do its best, but there are cases where it will guess wrong.

Best regards,
Vlado

Well, then I guess that's just the perception. I apologize for the comment then. However, you have to admit things are a bit confusing right now between different setups. I love Vray, never gonna stop using it, but a standard setting would be nice simply in terms of working with outsourced development.

It would be pretty great if Vray had a tool that managed gamma locally for an entire scene. For example normals are always in gamma 1, at least in my travels. I can't think of a scenario where you'd want anything different.

Most of my problems would be solved if we could get a list view of all the map types, with a global gamma override per map type. I have no idea how hard this is to make. I could tell normals, reflection maps, and opacity maps to be gamma 1.0, diffuse and etc to 2.2 all within 1 rollout instead of the hundreds of maps in a big scene. Heck even a script that goes through and does it, because it seems like an always necessary step in using it correctly. I left HDRI out because the current implementation turned out to be better than anything I could have imagined. I'm just the end user. This would also get around having to enter weird gammas in the max override like 4.4, .454, or 3.4 to get a gamma to the 2.2 you wanted... it's just a headache. (And I know it's a max problem not a vray problem but it's confusing regardless.)

I don't know what goes on under the hood, and I don't know the theory behind the math. I just know things don't always seem to sync up perfectly in various workflows. Probably I am doing something wrong, but I've been trying to sort all this out for 8 years it seems. I appreciate the total control that vray gives me, but finding the 'reference' point which is the correct setup so you know how to deviate from it is the meat for my potatoes. I've tried all of them in this thread and for example fog color seems to be immune to gamma changes, or it's just odd to use for me.

I am certain most of the problems are with max itself, and I can see Autodesk not wanting to fix a lot of them. I thank you for your time and patience with us as we try to understand how it all fits together.

[jacksc02]

Just a little side note on max 2014.
The output gamma setting is not an adjustable value through the max preferences which is very annoying.

[raid]

I tried the implementation by Vlado now and i seem not to get it....
VrayRt is no applying the right gamma.. so forget it.
Then trying to apply color correction on every material??
Imagine this scenario i got atm: create an interior till tomorrow 4pm with some modelling involved and specific furniture that has to be bought...all with stacked materials etc with of course no color correction, its jsut impossible. Cant there be a button in the render rollout that applies gamma correction to every material that has no color correction with gamma seto to 0.45?
I just keep rendering a wrong color output, am pretty much confused by the time now and frustrated...

[Mokiki]

please delete me.

[ruud3dv]

I've got a problem still with all incoming bitmaps (jpg textures from photographs / as I understand these usually have gamma 2.2). They all are assumed to have gamma 1.0 when set to Automatic. So i have to manually set them to override gamma 2.2.

I'm using the following settings (as Vlado recommended) in Max 2014 x64, SP1, with Vray 2.40.04:

Max gamma 2.2 enabled
V-Ray VFB sRGB button ON
V-Ray color mapping Gamma 2.2
V-Ray color mapping "Color mapping only (no gamma)"
V-Ray Linear workflow OFF

Furthermore I have:
Affect color picker = on
Affect material editor = on

Here's what I did:
- create a new scene
- add a Vray material with a bitmap, select a jpg, gamma set to Automatic
- in the material editor the material is clearly washed out, same when using the 'View Image' button on the Bitmap rollout
- click the bitmap file in rollout, set override to 2.2
- now the material editor looks fine, and also clicking the 'View Image' button shows the image correctly.

If 'Automatic' would have used 2.2 then the image should have looked the same as when I set it to override on 2.2 right?
So to me it seems that 'Max 2014 is (or at least should be) smart enough to identify format and open/save with correct gamma setting..' doesn't work for me, or I'm making a workflow mistake somewhere. As I understood with the new Max 2014 automatic gamma, jpg textures should be assumed to have 2.2 gamma when gamma correction was enabled. Am I wrong?

Edit: found the maxscript setting fileInGamma, it was set to 1.0 for some reason. After setting it to 2.2 and closing and restarting Max it seems to work ok now for new scenes! Can this have happened when using existing scenes from 3ds Max 2013 in which i used LWF?

Edit2: found the offender: the awesome GhostTown plugin from kilad sets the fileInGamma to 1.0

[Svetlozar Draganov]

Thank you very much for the feedback.

[DPS]

Just a clarification, regarding gamma corrected gradients.

What I meant was that for our use in a 3d application, it seems strange that the gradient does not get the appearance of being evenly distributed when corrected, since we need this gradient to make (informed) decisions based on visual input on what colour/value is used for something. The result now is that we rely on past experience and/or rendered previews to chose our values, as opposed to "getting it right" at the first stage when looking at the colour swatch. This is of course a bit exaggerated, as we seldom actually get it right before seeing the rendered result and tweaking.
Should not the correct gamma for "perception" actually make the corrected gradient appear completely evenly distributed?

I recently starred using gradient mapping, and am interested in the best approach.

Example: I used a greyscale sRGB bitmap with 2.2 input gamma correction. This was used as the source map in gradient ramp, set to mapped. I sampled various colours from photoshop and manually converted these to linear values and i used these colours in my gradient ramp.

The result looked wrong so i put the gradient ramp through a colour correction node and applied a 1.6 gamma. I basically fudged it as I didnt know how to match my grsdient remap to the one I did in Photoshop. 1.6 because 2.2 was clearly not working.

I agree with trixian - the gradient needs to appear linear in order to be intuitive when remapping a procedural 3ds map.

Exactly where should i be applying gamma correction in the above circumstance?

[Svetlozar Draganov]

Can you send and show us a few examples of what work-flow are you using?
What are the results? Why these results are wrong ? How do the correct results should look like ?
I am trying to run some tests here but I am not sure if I am following the same work-flow.

[DPS]

Basically - take any greyscale image into photoshop, apply a gradient map to it - create whatever gradient you want. And then try to recreate this in 3DS Max.

I've created an example Photoshop and Max file.GradientGammaTest.zip

[tashko.zashev]

Hi,

Thanks for sharing your files.
I've also made a test with this and here is the result:


I think that there is no gamma issue for this workflow.
For the Max scene i have made few changes to the lighting setup. Only the default lights are ON and the Gamma input for the map is set to use the default one.
Made this to be sure that no additional adjustments has made to the shader.

Unfortunately i don't have Photoshop on my PC, so Gimp is used instead.

and the link to the Max file :
GradientTest_01.zip

I hope this is the result you are looking for.

[DPS]

How did you create your gradient?

Surely a 255 Red isn't a good test as a gamma correction won't affect this. Correct me if I'm wrong though.

Thanks for taking a look.

[DPS]

And I've setup the gradient again using the same colours and gradient flag positions as in photoshop using your setup.

The resulting render is too dark. I tried this on another project, sampling paint colours from a photographs and the result was much too dark compared to if I just used the gamma corrected value inside the vray material diffuse colour swatch

.

[tashko.zashev]

How did you create your gradient?

Surely a 255 Red isn't a good test as a gamma correction won't affect this. Correct me if I'm wrong though.

Thanks for taking a look.

My mistake here, you are correct. No gamma correction required for this setup.
I've prepared a new setup:
GradientTest_02.zip
and screenshot:


Red channel with value "128" and color correction node added to the Gradient ramp with gamma inverse.

[Rens]

Max gamma 2.2 enabled
V-Ray VFB sRGB button ON
V-Ray color mapping Gamma 2.2
V-Ray color mapping "Color mapping only (no gamma)"
V-Ray Linear workflow OFF

Furthermore I have:
Affect color picker = on
Affect material editor = on

The above works very well for me.

The rule for input bitmap gamma is:
- Linear formats (exr, hdr) always gamma 1.0.
- Other formats like JPEG where the map will be directly visible (for example diffuse): gamma 2.2
- And where it's not, i.e. technical maps like bump maps and masks: gamma 1.0

Basically there are two options for importing bitmaps correctly:
- Convert all of your files to EXRs and set the global bitmap input and output gamma to 1.0. Not the best obviously if you have tons of 8bit maps.
- Or set the gamma each time you import a new bitmap. Set the global bitmap input gamma to whichever value you use most so you can leave it at default for those maps.

There's no way for max to know where you're going to use that map, not beforehand anyway, so there's no way to auto-set the gamma for you. Maybe V-Ray during rendering can see that and make changes accordingly.