Compositing doesn`t add up to RGB result

[MANUEL_MOUSIOL]

Hello everyboy,

I am sorry to start another thread about compositing - I went through a few already and thought I would be able to replicate the straight RGB render by compositing the elements in Photoshop - but it just does not add up to the acutal render, no matter what I do.

Two phenomens here:

• Either some detail lighting is missing (sharp,detailed highlights) or
• the overall brightness is totally different

I am talking about very simple product shots here - studio lighting.
What I am trying to do in the end, is to have a claymodel onto which I compose the actual texture (which I rendered as a separate ExtraTex element) in Photoshop. I would compose this texture onto everything at the end via Multiplay or Overlay, I guess, but I am not even coming the same RGB result with my claymodel.

Right now I am comping like this:
Reflection (Linear Dodge - Add)
RAW Total Lighting (Multiply)
Diffuse (Normal)

RAW Reflection does look like it could maybe give me that missing highlight and detail, but I wouldnt know how to comp it in..


What am I doing wrong?

BTW, in the beginning I was thinking of just creating a claymodel (i.e. my product with all the material settings it should have just without the diffuse slot being active) and then layering the ExtraTex (the texture the product has) on top of that RGB rendering via Overlay, but again - these bright and detailed highlights are missing.
Any ideas for that kind of workflow?

I attached my results and the scene as well as the renderoutput.

Sorry for bothering everybody and thank you very much for any help!

Manuel

[Dave_Wortley]

Jpeg's won't give you the right result, you need EXR in 16bit for lighting, there is also an option in the colour options to blend RGB color images using gamma 1.0.

[MANUEL_MOUSIOL]

Ah, ok. I see. When using 16bit files it worked - but now I am having a problem with the Gamma. Seems like its always applying 2.2 gamma - too washed out.
How would I go about the blending using 1.0? Are you talking about Photoshop or Vray?

Thanks a lot for the help!

[grantwarwick]

Change your 3dsmax gamma output if you aren't using 32bit EXR's (Which I strongly reccomend as we aren't living in the stone age anymore :P )

[MANUEL_MOUSIOL]

I am sorry, I thought I shouldnt change 3DS Gamma settings and leave it to Vray, but in the end keep it at 1.0, linear workflow.
I tried the EXRs and it works fine if I merge everything before converting it to 16bit (since I cannot work in 32bit the whole time as some functions are not available and it is too heavy), but if I do not want to merge all the layers but still want to composite AND keep the look of my VFB (i.e. not washed out), how would I go about that?

I guess that I am not understanding some basic concepts here. Instead of bugging you with questions, maybe a good read-up would help. Any articles that will basically solve my problems that I could read?
Sorry for being such a newbie ;(

[Morne]

max gamma and also file in/out set to 2.2
vray color mapping linear, gamma 2.2 - mode: none
vfb tick srgb button
save to exr
don't use the "lwf button"
that gives you a linear workflow 1.0

thats it

[MANUEL_MOUSIOL]

Sorry for the very late reply. I was not able to get online for a while.

Thank you so much for the advise! I am getting good results with your workflow now.

Thank you again!

[TheLooopCGI]

Sorry to bring up an old thread but I have a question following up this topic so replying here seems like a more clever idea than starting a whole new thread.

Anyway, I've been dealing with the same issue as Manuel and I solved it just like Dave Wortley suggested by using 16bit EXR files. It's not really ideal though since EXR files are always opened as 32bit in PS and assigned an sRGB color profile which degrade the quality a bit. I tried to use 16bit Tiff files instead saved with gamma 1.0, composed in PS and applied levels adjustment on top with the middle slider set to 2.2. Unfortunately the result is quite different than the beauty pass. I also tried to save the tiffs with 2.2 gamma baked in but then it's really different.

Why the 16bit EXRs work but 16bit TIFFs wouldn't?

I'm testing with a simple scene. A black environment, a grey plane with a red sphere with fresnel reflections sitting on it and a VRay rectangle light shining down on the objects. No textures or anything else.

My color mapping settings are:
Linear multiply
Gamma 2.2
Mode: None
LWF checked

Thanks for any pointers.

[TheLooopCGI]

To be precise - when I use 16bit TIFFs, the composition of render elements does equal the beauty pass, but it's wrong.

The same beauty pass of the render saved in 16bit TIFF and applied 2.2 gamma in PS looks different than 16bit EXR opened as 32bit in PS. How come?

[Dariusz Makowski (Dadal)]

max gamma and also file in/out set to 2.2
vray color mapping linear, gamma 2.2 - mode: none
vfb tick srgb button
save to exr
don't use the "lwf button"
that gives you a linear workflow 1.0

thats it

So you are telling vray to apply Gamma correction in Color mapping and then for display purposes u are teling vray to apply SRGB = 2.2 gamma again on ur existing 2.2 gamma render. In which result u have 2x gamma applies + ur exr is NOT linear but already has a 2.2 gamma applied from Color Mapping.

This is wrong. vray color mapping should ALWAYS remain at 1.

- At least in maya when I test it that's what I get not sure about max.

You can get 99% Match using 32 bit files EXR. U can NOT get 99% match using 16/8bit files! Its not yet possible. Photoshop blending mode screen is inaccurate.

[TheLooopCGI]

Dadal, what you're reacting to is 3 months old.

However I think you're wrong there. When you set the color mapping mode to None, Vray only calculates the image sampling in 2.2 gamma (and some other internal calculations I presume) but you still get a 1.0 gamma picture in the VFB. That's why you have to tick the sRGB button in the VFB to actually see a gamma 2.2 picture.

Could we please resolve the issue of how come a 16bit TIFF beauty pass is not the same as 16bit EXR file? No blending mode present.

[Dariusz Makowski (Dadal)]

Humh yea Im bit of sick and tired of all the eternal gamma discussion topics :/ I admire chaos staff for surviving it.

In any case here is the video explanation. Sound got out of sync so ehh shit happens?

Hope its the same way in max...
http://youtu.be/J6RzYQ2ObQk

Just retried the Dont affect colors button with gamma 2.2. It looks like it moves the noise levels to different values... I guess gamma 2.2. Which is interesting. I guess in max its on by default?

[TheLooopCGI]

The "Don't affect colors" button equals to "mode: none" that Morne and me were talking about. It display's the image in VFB in gamma 1.0 even if you set the linear mapping gamma to 2.2 but the noise levels are different so you don't lose quality when you adjust the gamma later in PS. In any case you -have- to set the gamma to 2.2 so you would get the correct render result. The affect colors checkbox only changes the way you compose the render in PS later.

In any case, thanks for the video, but the question is not -how- to render in LWF but how to save the files so you would not have to work in 32bit in PSD, which I see you do.

[Dariusz Makowski (Dadal)]

I don't work in 32 bit. You take that 32 bit file down to 16/8 bit. Then use Screen instead of Add. It will not match 100% to ur render. It never will... The Screen mode in photoshop does not work properly and it just fakes the proper add mode... its bit complicated.

The dont affect colors yea its like you said. You shift ur noise levels and thresholds from linear to gamma corrected which is uhh I suppose a good thing?