Color spaces support (aka OpenColorIO v2.0)

Discussion related to the LuxCore functionality, implementations and API.
bartek_zgo
Posts: 103
Joined: Mon Oct 26, 2020 11:42 am

Re: Color spaces support (aka OpenColorIO v2.0)

Post by bartek_zgo »

Yes you are right. In the code it was correct, but in text I misspelled. I have corrected it.
Sharlybg wrote: Sat Jul 02, 2022 12:32 pm Thank you very much Bartek for this really detail explanation
of ACES in Luxcore. This is going to help a lot. By The way I Think
you want to say ACEScg instead of " ACESng"
bartek_zgo
Posts: 103
Joined: Mon Oct 26, 2020 11:42 am

Re: Color spaces support (aka OpenColorIO v2.0)

Post by bartek_zgo »

Sharlybg wrote: Sun Jul 03, 2022 7:12 pm Diffuse color input space seem to be right with ""Utility Raw"" instead of ""Utility Srgb Texture""
I think this is because Blender internally use Linear Color Space. If you take HTML color #808080 that is 128,128,128, it should be 0.5, 0.5, 0.5, but in blender you will se 0.21, 0.21, 0.21. So if you want to pass sRGB color to ACES you have to use "Utility Srgb Texture". But if you have color converted to Linear Color Space (like in blender) you can not apply the same transformation again.

There is still one thing that I do not understand. Linear Color Space used in Blender is not the same as ACEScg (as long as you do not chage ocio config file for Blender). ACEScg is linear but a little bit different. So I'm not in 100% sure if "Utility RAW" is the correct option. For sure it is much better than "Utility Srgb Texture".

You have done test with one color. It is not enough. In that case it may look correct for you but it may be not the same for other colors.
Could you be so kind and import HDRI OpenExr background and check if it looks identical in render or not.
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Sharlybg
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Re: Color spaces support (aka OpenColorIO v2.0)

Post by Sharlybg »

With the blender implementation of ACES for Lux i have got HDRi didn't have input colorspace but the dev told me that it was Raw input.
And in my test it was looking very correct and simillar to Cycles hdri + input utility linear srgb
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