LDR Multi-Pass images with OCIO

[Meet]

Hello, is it possible to save render passes with OCIO look(as viewed in octane IPR) baked in as 8bit PNG/Jpeg images?
From reading the documentation I understand that when saving HDR images(EXR/TIFF 16/32bit) it's best to use Octane output and add the OCIO look in post, which is fine.
Now the manual also suggests to use C4D save/export(with proper octane render settings) if one wants to match the look of the octane IPR with OCIO enabled, which works perfectly for final images, but doesn't seem to work properly when one wants to render multiple render passes.
For example if one wants to render main + refraction passes as PNG image with OCIO look baked in to match the octane IPR, from my testing, only the main image renders as expected and the exported refraction pass doesn't match the octane IPR render pass. So, is this expected? cause when using blender or standalone there doesn't seem to be any problem when exporting LDR OCIO images via octane export.

Using Studio 2021.1 R3
C4D R25

[aoktar]

Why do you wish to use LDR else of HDR. There's not any reason to desperately trying to do use it. You have to use linear color spaces if you want to make re-compositing of passes and LDR is not for that.

[omardex]

Hello, set the frame buffer as 8bit and assign the output to ocio Output SRGB, be aware that this is baked into the files and further compositing is super limited.

try not to use the c4d save system use the one in the octane render settings instead.

check this video. https://www.youtube.com/watch?v=4t3qHtwyWcs

people of knowledge, there is no one absolute way, only alternatives and multiple paths to get to the result.

But I give that the proper way is to export HDR files in exr for better color management and compositing.

Note:one issue I'm having exporting LDR passes from c4d using ACES is that I have to assign manually srgb color space in affinity or photoshop, if I save directly from the IPR or from octane standalone I don't have to do this.

[Meet]

Why do you wish to use LDR else of HDR. There's not any reason to desperately trying to do use it. You have to use linear color spaces if you want to make re-compositing of passes and LDR is not for that.

I understand that it is best practice to store passes as HDR images and recomposite them later but saving baked-in OCIO look in LDR images is quite handy for quick renders. I am moving from blender octane to c4d and asked this as this was pretty easy to set up in blender with the octane output or blender output, so was wondering if this was a bug with c4d octane, but from reading the manual I understand that saving LDR images with OCIO as octane output is not an option for some reason.

Hello, set the frame buffer as 8bit and assign the output to ocio Output SRGB, be aware that this is baked into the files and further compositing is super limited.

try not to use the c4d save system use the one in the octane render settings instead.

check this video. https://www.youtube.com/watch?v=4t3qHtwyWcs

people of knowledge, there is no one absolute way, only alternatives and multiple paths to get to the result.

But I give that the proper way is to export HDR files in exr for better color management and compositing.

Note:one issue I'm having exporting LDR passes from c4d using ACES is that I have to assign manually srgb color space in affinity or photoshop, if I save directly from the IPR or from octane standalone I don't have to do this.

Thank you but I as you can see from the in the settings I attached, I have the settings set up just as you mentioned

[jayroth2020]

Actually, your screen shot has you saving using the Cinema 4D saver, not the Octane file saver in the Render AOV groups tab... Disable the Save option in the the list to the left, turn on the Enable toggle in the Render AOV group tab, and choose the file location and name. In the Main tab, set the Buffer type to HDR and the Color Space to OICO:/Output(Output - sRGB). Make sure you also have the view in the Camera Imager of Octane settings set to ACES:sRGB. DO NOT USE FORCE TONE MAPPING

[omardex]

I believe he already said that he has done that.

Have you tried assigning to the incorrect resulting images from c4d the srgb color space (assigning not converting) this resolves the incorrect colors and matching for me when saving from c4d LDR, the other versions of the renderer work good.

[Meet]

Actually, your screen shot has you saving using the Cinema 4D saver, not the Octane file saver in the Render AOV groups tab... Disable the Save option in the the list to the left, turn on the Enable toggle in the Render AOV group tab, and choose the file location and name. In the Main tab, set the Buffer type to HDR and the Color Space to OICO:/Output(Output - sRGB). Make sure you also have the view in the Camera Imager of Octane settings set to ACES:sRGB. DO NOT USE FORCE TONE MAPPING

Yes, the documentation says to use C4D save instead of octane save when wanting to export in PNG with OCIO look baked in. I have already tried what you suggested and didn't get the proper results, I tried it again now and same, IPR not matching final output. It looks like the sRGB profile is getting applied twice to the exported image.
I would like to clarify again to avoid any confusion that I would like the result to be exported along with different passes/AOVs in PNG format with OCIO look baked in, something which can easily be achieved in Standalone or Blender Octane

Octane IPR on the right not matching PNG image output via octane export using the settings on the left

[aoktar]

Png is marked as sRGB for saving if you are using it with default sRGB. But any OCIO profile is assumed linear. Set it as linear on saving.

[omardex]

yes the srgb curve is applied twice if the compositing software automatically converts the files to the color profile of the software used,

In affinity this is solved in the preferences turning off convert opened files to working space (I know you probably are not using this software but this is the settings that keeps the original color space in the file to apply the srgb, and the one I use to work on static images.)

and Im insisting in this because I had the same situation as you when learning about aces and ocio, one of the test I did was keeping the look and forgetting about the ocio part in the compositing software using LDR images, from c4d. I believe this is a solution, an incorrect one in a pipeline

and you are right at least standalone doesn't do it, the LDR images are output correctly

[aoktar]

Standalone has the full control over all process but in picture viewer we don't for every parts. So you have to use correct combination by hand and with my advices.