Author Topic: Corona 11 ACES Workflow  (Read 1470 times)

2023-11-30, 22:42:29

Serj-3DVision

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Hello, after seeing that Color Management were added to corona 11 i'm trying to understand how i can stat to use it.

I'm trying to understand why in Corona Framebuffer there are no conversion from ACEScg to sRGB.
Im using default max2024 OCIO config in Color Management tab, newer config gives me error that it is not supported/compatible.

Image 1 - screenshot how it looks in Frame Buffer.
Image 2 - file saved in EXR
Image 3 - standard conversion from ACEScg to sRGB

From my experience with Octane for example, what i see in Frame Buffer (image 1) should be exactly the same as Image 3.

Thanks in advance.
Sergei Scennikov | Israel | Tel-Aviv
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3DVision | Corona Materials Library

2023-12-08, 16:00:45
Reply #1

maru

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Hi, sorry, I don't have an explanation yet. I will try to get it for you, but first I have a more general question: can you please explain what exactly you would like to do and why? Are you trying to display your image in a wider color space, for example because you have a monitor operating in a wider color space? Or is it something completely different? Or maybe you are just testing the new features and looking for information?

Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2023-12-13, 15:16:07
Reply #2

maru

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Here is what is happening:

When using a custom color space (the "OCIO/ACES workflow"), the the VFB content is in linear sRGB instead of the expected gamma-corrected sRGB  - this is why it looks "wrong". The reason for this is that with the current color management implementation, Corona does not respect the 3ds Max Display and Views > Frame Buffer Default option.

We are working on improving the color management support and also trying to come up with a workaround that would allow users to see the image in the VFB as expected.
Also, we are planning new VFB features for Corona 12 (and a reskin), with the intention of making working with OCIO/ACES easier.

What works correctly right now is:
- Loading textures created in specific color spaces (there is a new drop-down for this in Corona Bitmap (and Corona Color))
- Rendering in a specific color space (all internal calculations are done in that color space)
- Outputting files with the selected color space and conversion (3ds Max 2024 "color management" section in the "Save image" dialog).

What we suggest:
If you do not need to load textures created in specific color spaces or are not planning to render in specific color spaces to bring your images into 2D editors or compositing software, leave the 3ds Max color management settings at the legacy gamma workflow.
Otherwise, you can use the available options (loading textures, customizing 3ds Max color management, outputting in specific color space), but bear in mind that the result visible in the VFB will be displayed in linear sRGB.

We are also working on a color management guide that we will share with everyone.

Sorry for not fully supporting everything. We are doing our best to improve this. Meanwhile, we are still interested in hearing what color management options you are interested in and why.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2023-12-13, 16:07:42
Reply #3

CARL

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Hi, I think we should have in Corona the same color management as in V-Ray, same possibilities, not less.

And then make a: ''one and only guide'' or Corona Academy lesson about this topic: ''COLOR MANAGEMENT'' We as designers or 3D artists need the best color accuracy, and potential of our tool.


Thank you for your interest in users opinion, and great work.

2023-12-14, 12:36:06
Reply #4

Getoray

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I also think Corona renderer should be the same as Vray's color management method

2023-12-14, 12:52:35
Reply #5

sebastian___

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Also, we are planning new VFB features for Corona 12 (and a reskin),


For the reskin don't forget to make the VFB be able to be resized smaller (if posible) because the old version had a hard limit, which was bigger than if you would use the VFB in a viewport.

2023-12-14, 16:53:00
Reply #6

maru

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In the newest Corona 12 daily build we now have a new Gamma Correction operator which you can add in the VFB to bring back the sRGB gamma to the image you are viewing.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2023-12-15, 09:06:56
Reply #7

piotrus3333

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In the newest Corona 12 daily build we now have a new Gamma Correction operator which you can add in the VFB to bring back the sRGB gamma to the image you are viewing.

most welcome addition, thank you.
is adding “inverse” option planned? to linearize piecewise srgb?
Marcin Piotrowski
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2023-12-15, 10:32:06
Reply #8

maru

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is adding “inverse” option planned? to linearize piecewise srgb?

This is now reported as a feature request, but can you additionally explain why exactly you need this option? In what cases would you be using it?

(Internal ID=1268084774)
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2023-12-15, 10:41:08
Reply #9

piotrus3333

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is adding “inverse” option planned? to linearize piecewise srgb?

This is now reported as a feature request, but can you additionally explain why exactly you need this option? In what cases would you be using it?

(Internal ID=1268084774)

to somewhat fix Corona's lut handling.
https://forum.corona-renderer.com/index.php?topic=40988.0

thank you.
Marcin Piotrowski
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2023-12-15, 10:42:38
Reply #10

maru

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So you would "linearize" the image, then apply LUT, and then gamma-correct it again?
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2023-12-15, 10:46:22
Reply #11

piotrus3333

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So you would "linearize" the image, then apply LUT, and then gamma-correct it again?

yes,
to remove under-the-hood gamma transform before lut and get rid of the viewing transform of frame buffer.
Marcin Piotrowski
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2023-12-15, 10:47:51
Reply #12

maru

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Ok, thanks for the explanation!
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2023-12-15, 15:51:45
Reply #13

piotrus3333

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Hello, after seeing that Color Management were added to corona 11 i'm trying to understand how i can stat to use it.

I'm trying to understand why in Corona Framebuffer there are no conversion from ACEScg to sRGB.
Im using default max2024 OCIO config in Color Management tab, newer config gives me error that it is not supported/compatible.

Image 1 - screenshot how it looks in Frame Buffer.
Image 2 - file saved in EXR
Image 3 - standard conversion from ACEScg to sRGB

From my experience with Octane for example, what i see in Frame Buffer (image 1) should be exactly the same as Image 3.

Thanks in advance.

and regarding the ACES workflow in Corona/max - one thing to be aware of - 3dsmax (and even VRay) seriously lags behind in ocio implementation: for example you can not see properly aces 1.3 output with ocio configs available from aces githubs. you are stuck with 1.2. you need to make a custom config file that works around some newer ocio features (display - view - look structure: this is now only supported by VRayOCIO map weirdly)

you might be better off using just luts in CIE for the sake of simplicity.
Marcin Piotrowski
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2023-12-17, 14:25:35
Reply #14

Salvatore CDA

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I don't get all these ACES settings; ACES Settings are in the 3D Software, and ACES Settings are in the renderer and don't communicate. I still use the standard Gamma correction Colorspace in 3DSmax and render out all with Corona render and save as TIFF 16bit, as I did in the last few years; that works perfectly.