Wrong color rendering

[marty030]

I have stumbled across a weird behaviour in Vray 3.007 to what someone might have a solution or hint what I might do wrong.

When rendering an object in a scene I had to change the color to a specific yellow-orange tone. When doing previews
nothing changed, which was quite strange. Even more so that the colors in the colorpicker/MatSphere/viewport
didn´t match. So I tried several ways. Using a VRayColor in the Diffuse slot made it look coherent in
the MatEditor but the rendering still wasn´t correct. Even by using a texture with the same color it
didn´t produce the same result in rendering (BitmapInput is set to Automatic / 2.2).

My Gamma Setup looks like this:

[Gamma]
DisplayGamma=2.200000
Enable=1
DisplayCorrectionMode=1
CorrectColorPickerState=0
CorrectMtlEditorState=1
InputGamma=2.200000
OutputGamma=2.200000
LUTFileName=
DisplayCorrectionPrefMode=1

(It´s just for the record, it doesn´t matter if I switch to another setting, the result is the same and was fine before.)

You can examine the issue in the attached examples, where you can compare the colors inside the MatEditor to final rendering.
For the first one I chose just the color in the diffuse slot, then I put the color inside a VRayColor and lastly
I used a texture.

It seems to me in the rendering the color gets treated with a gamma of 4.4, so somewhere on the way it doubles, because
when I uncheck sRGB in the VFB the scene is too dark, but the objects color look fine. Weird!

I also attached the scene to help reproduce this behaviour.

Thanks in advance
martin

[vlado]

You have set up the color picker to show you non-corrected colors. Is this on purpose? It means that you are seeing the wrong color in the picker.

Best regards,
Vlado

[marty030]

Forgot to mention: Max2014 with SP5

Yes, it is set on purpose. I want to match the colors from inside Photoshop to VRay. Take for instance with RGB 40/60/10 and when ´AffectColorPicker´ is checked it shows the colors too bright in my view when compared closely. Unchecking looks better to me and when VRayColor in the diffuse it is consistent to me.
I know everybody checks it to ON, but so far it didn´t make sense me. Am I so wrong?

[marty030]

Found my main problem, the brightness of the scene light was set too high. stupid! Now it looks as it´s supposed to be.

[marty030]

Vlado, it´s still unclear to me why I have to check the "Affect Color Picker" for correct color view when they are clearly too bright compared to PS. If one tries it with for instance with RGB 40/60/10 it doesn´t look right in the MatEditor and the rendering is too bright. It´s like there´s a double gamma in play. When I fill a layer in PS with that color and I put an exposure layer with Gamma2.2 on top it looks like after having checked "AffectColorPicker".
With the help of VRayColor und unchecking the ColorPicker it all looks and renders consistent: I choose a color in PS, transfer it to Max/Vray, see it correct in the MatEditor/Viewport/Rendering.

Overall it doesn´t feel like to me the gamma input for colors is treated the same way as with textures, whatever the reason..

[Morne]

If you're using just the RGB values you have to stick those into a VRayColor and then set the VRayColor gamma to 0.4545
That will match your RGB color picker in photoshop then

It has to do with a gamma corrected workflow. Photoshop and any Windows app is setup to already display the 2.2 gamma applied (Unless you're opening a 32bit linear image in photoshop)
The whole idea between the gazzillion gamma settings in MAX is to counter the 2.2 gamma that most things already have applied, so that you can work in a linear space (gamma 1.0)
So in fact when you're setting the VRayColor to 0.4545 that is the inverse of gamma 2.2 so it displays the curve as linear 1

What we do is afterwards copy the corrected color from the VRayColor and just stick that in the diffuse and then remove the VRayColor

[marty030]

And I thought I´m the only one giving weird thoughts on gamma..
Very interesting method of yours! And it works. So then this is confirmation enough for me that there´s a
grain of justification in my doubts of the all known gamma setting. Thanks for your insight!