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Wrong Colorspace ?

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Shahed Naderi
Wrong Colorspace ?
on Aug 3, 2018 at 10:41:39 am

hello, I just rendered a scene in cinema4d with different passes stored in a PSD file sequence, when I open the files in photoshop it looks identical to my renders inside C4D , but when I import them in after effect they look more saturated and darker , all passes , I couldn't figure out whats wrong , and idea
also, do you know how I can import OpenEXR sequence in after effects?

here are two screenshots of photoshop and after effects
https://imageshack.com/a/img924/3978/wwgaYb.jpg
https://imageshack.com/a/img924/8440/9JCDAV.jpg

-Shahed Naderi


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Andrew Somers
Re: Wrong Colorspace ?
on Aug 3, 2018 at 12:22:35 pm
Last Edited By Andrew Somers on Aug 3, 2018 at 1:38:39 pm

Hi Shahed,

The first thing I'll tell you is that the first of the two above (wwgaYb.jpg) is tagged with an icc profile called "linear color space", implying a gamma of 1.0. The second file is NOT tagged at all, and untagged images are generally interpreted as sRGB which has a gamma curve close to 2.22

Photoshop is by default working in a color managed workflow, interpreting color profiles embedded in the image to convert them to the working space (unless you turn this off).

After Effects however requires you to turn on color management by setting the working space to a profile.

Based on these images, I'm going to guess the settings that would be best for you:

In After Effects, set the project to 32 bit, sRGB, and Linearize Colorspace. Also select "adjust for scene referred profiles". Under "View" set "Display Color Management" and finally, set the interpretation for the image sequence you are importing to linear (if it is linear or convert it to linear if it is gamma encoded) in the clip's color management tab (o using the convert profiles utility effect on the layer).

It's common to render in a scene-linear light (gamma 1.0) in C4D, as scene linear is the way light works in the real world. And it's best to remain in a linearized working colorspace all through the compositing process until your final output.

NOW,

Having said all that, you do not want your C4D linear renders to be saved as linear 8 bit !!! That would be bad and have bad banding types of artifacts as 8 bit cannot hold the HDR nature of a scene-linear image. Ideally you want to save them to a file format that is natively linear and at least 16 bit. And PSD is not the ideal way.

But EXR is.

C4D outputs to EXR, and AE supports EXR files with the OpenEXR plugin and the ProEXR plugins. I believe these Fnord plugins are all included for free in AE. But you can also download them free from Fnord, along with documentation on using them.

The ProEXR plugins include one called EXtractor which allows After Effects to access the UNLIMITED number of channels that EXR files support (much like PS Layers).

I recommend 16 bit float EXR as the preferred interchange format for VFX and CGI. Working with C4D it's ideal when you render in a linear light space (gamma 1.0 — I believe it's the default for C4D), so you can export in linear light which is the native transfer curve for EXR. Also EXR supports channels of different bit depths in the same file — 16 bit float is enough for images, but you might want a 32 bit channel for Z-Depth for instance.

As the native/preferred gamma of EXR is 1.0, you can import direct into AE 32 bit linear mode with no transfer curve issues — nevertheless it IS still important to know the color primaries that were used rendering in C4D. Since it sounds like you might be doing things at default values, the primaries are probably Rec709/sRGB (these two profiles use the same primaries).

As for your current workflow, In AE you can change the way the imported footage is interpreted and assign it any profile you want. Right click the footage and select "interpret footage", then set the color management settings with the appropriate profile. Or you can add the utility plugin "Convert Color Profile:" which allows you to set input/output profiles and control linearization.

*** If your AE working space is scene linear with Rec709 primaries, and your footage is scene linear EXR with Rec709 primaries (essentially the EXR default), then you can set the imported footage to "Preserve RGB" which turns off color management for that clip as it's not needed, improving performance by avoiding color transforms.

A further tool for color, LUTs, and profiles is the free OpenColorIO, downloadable here.

And finally, I wrote this article discussing working vs output color spaces and linear workflows that you might find helpful.


Best of luck

Andrew Somers
VFX & Title Supervisor
http://GeneralTitles.com


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Steve Bentley
Re: Wrong Colorspace ?
on Aug 3, 2018 at 8:42:05 pm

Double check the color space in C4D's render settings when using EXR's. In R19 it defaults, for some baffling reason, to sRGB instead of none or linear or 709. This is like buying a ferrari with a rev limiter on it set to 1000 RPM. Once set your project will be fine for all of its iterations, but I've noticed when starting a fresh project, there is the pesky sRGB again.



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