Render Light Passes colour space different from main render colour space
Posted: 14 May 2019 10:12 AM   [ Ignore ]  
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Joined  2016-10-25

Hello,

I’m doing a render in C4D r18 and trying to get the separate passes for all the lights in my scene to use the same color profile as the main render.

I have my main render set to use srgb image color profile, but the light passes seem to be rendering with a linear profile, is there any way to control this?

I am able to get them both to look correct if I use a linear workflow for my pipeline (AE and C4D) but I am curious why the passes don’t render with the main render color profile settings?

One way I found was to render the passes in 16 bit then do a gamma shift to 2.2 for the passes in AE to get them to match my main render appearance.

Thanks!
Nick

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Posted: 14 May 2019 10:45 AM   [ Ignore ]   [ # 1 ]  
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Hi Nick,

I’m not the one to ask for this fake retro work, it works against all my understanding of quality work. Sorry.

The sRGB space is the lowest color space (used for web stuff, like, etc.) and it is gamma based while using integer formats. I would not use a delivery space for any process. Since you mentioned After Effects, the delivery would be BT REC 709 for HD content, and again, this is a tiny color space as well, and to use it during (pipeline) work is certainly not the best idea at all. Some might even tell you sRGB, and REC 709 are similar, well, they are not.

To go into a gamma space with light-passes is a huge mess, I would not like to support this in any way. In After Effects to get anything to a certain quality, the process internally must be linear anyway. So, to use the Cinema 4D linear renderings (internally always) and turn it into gamma stuff, then load it into Ae and have it internally converting it to linear, while outputting it then back to gamma(?). Sounds pretty much like wasting process power and quality, right?

The main idea why the world changed to linear way over a decade ago was needed as the processing based on gamma material was just utterly wrong, and it showed hugely, e.g., in multi-pass shadows. If you adjust anything in gamma land, it might move up or down a curve (i.e. distorting values), then a second adjustment will have not really a decent chance to bring it back.

Alpha channels and Buffer are not gamma based either, and to mix and match all of those thingsā€¦ well, I really don’t know why. HDR and UHD are more and more used these days, and sRGB or Rec709 will look dull and aged already compared to even simple extended dynamic range.

If you want quality, use linear for any process, from a to z.

All the best

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Dr. Sassi V. Sassmannshausen Ph.D.

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Posted: 14 May 2019 01:04 PM   [ Ignore ]   [ # 2 ]  
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Joined  2016-10-25

Great, thank you! Yep I agree, and it makes sense that the passes are all going to render in linear, it would be strange to have it any other way..

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Posted: 14 May 2019 01:11 PM   [ Ignore ]   [ # 3 ]  
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Thanks a lot, Nick!

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Dr. Sassi V. Sassmannshausen Ph.D.

Photography For C4D Artists: 200 Free Tutorials: Texture, Panorama, HDRI, Camera Projection, etc.
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