Messages

1

[Max] Bug Reporting / Is this behaviour expected in colour managed 3dsMax versions?

« on: 2025-05-02, 10:55:45 »

max 2024 default ocio config, Corona 12 hf2:

after changing colour management settings to Rendering Color Space: scene-linear rec 709-sRGB Corona locks Internal color space in Development/experimental stuff to sRGB (linear rec 709).
is this behaviour expected and as designed or should it be considered a bug?
as from the very beginning internal rendering math in Corona was always performed in at least Adobe wide RGB space this might lead to some users switching from 3dsMax default ACEScg to scene-linear rec 709-sRGB, expecting legacy-like (gamma 2.2) setup but in fact limiting Corona to pre-Corona, 2011 VRay's colour math with all its lighting bugs and limitations.

2

[Max] I need help! / Re: sRGB image in Direct visiblility overide

« on: 2025-05-01, 12:36:42 »

@piotrus3333 what am I doing wrong? :)
1 - set custom config in 3ds Max and load your OCIO
2 - set global default view transform to ACES 1.0 SDR-video - this way we get identical result to the default 3ds Max OCIO color management setting
3 - load a .jpg bitmap and pick "ACES 1.0 SDR-video sRGB" as its color space
4 - render

Unfortunately, the bitmap I am using is still "tonemapped". For example sampling a pure white color gives RGB207.

bug in CoronaBitmap node?
works as expected with OSL UberBitmap (texture is 0.0 for black and 1.0 or white):

3

[Max] I need help! / Re: OCIO / ACEScg

« on: 2025-04-30, 14:03:48 »

RGB primaries set to "auto" should give you the correct results.

first time loading a bitmap into CoronaBitmap follows ocio rules (sRGB by default) but then selecting Auto gives incorrect result (Linear sRGB in this case).

and why there is no "gamma 2.2 sRGB" in the drop down options? this would be the natural option to pick for users coming from old 3dsMax versions.

4

[Max] I need help! / Re: sRGB image in Direct visiblility overide

« on: 2025-04-29, 17:38:14 »

You need to tag all input textures with correct colour space so Corona can transform the data into your rendering colour space. In user contribution section there is “alternative ocio for 3dsMax” containing “aces sdr video” colour spaces. use one of those.

5

[Max] Corona Goodies - User Contributions / Re: RED display transforms

« on: 2025-04-07, 08:51:36 »

not supported in 3ds Max.
Try Natron or Resolve.

6

[Max] Corona Goodies - User Contributions / Re: RED display transforms

« on: 2025-04-04, 08:46:21 »

OCIO config based on RED display transforms and RED Creative LUT Kit:
https://piotrus3333.gumroad.com/l/ydlfxm

7

[Max] Corona Goodies - User Contributions / Re: AgX in Corona

« on: 2025-04-01, 13:53:23 »

Ok awesome... ! Thank you. A lot to digest and figure out here so I might fire you some DMs when I get time to implement and test.
Cheers,

sure, no worries.

8

[Max] Corona Goodies - User Contributions / Re: AgX in Corona

« on: 2025-04-01, 13:12:34 »

you can actually also try these luts. made for Vantage so you will always end up with transfer function difference srgb vs 2.2.
I also never tested Corona's linear option in lut layer so no guaranties.
instead of log - use Reinhard curve (h compression 999 in Corona) - should be more precise compared to old double lut setup.

9

[Max] Corona Goodies - User Contributions / Re: AgX in Corona

« on: 2025-04-01, 12:53:05 »

@alexyork

skip the Corona Tonemap Control and just transform the backplate into your rendering space, linear rec709 in this case.
for this you need to reverse the AgX Punchy display transform. lin rec709 backplate will get back to AgX Punchy via frame buffer corrections. if you need to colour correct the backplate in Max do it in lin rec709 so its nice and tidy.

you need the original AgX ocio config from Troy Sobotka: https://github.com/sobotka/AgX

attached screenshot shows conversion done with VRayOCIO node, you can do this with Affinity/Photoshop/whatever else. 3dsMax 2024 setup with this AgX OCIO file should be able to convert it too.
there will be slight differences as luts I made ale limited in precision by Corona's cineon log conversion in lut layer.

10

[Max] Corona Goodies - User Contributions / Re: Alternative OCIO config for 3dsMax. ACES 2.0 and a few other view transforms.

« on: 2025-03-19, 07:35:24 »

Hi Piotrus, im looking at those profiles, one simple question, if I want to save a render in Jpg format, wich display and view transformation should i use to be able to see it as in the corona viewport ?
I have tried a lot but cant get an image that looks like VFB, if i export an exr i can view them in davinci using the correct transformations.

hard to say without seeing your settings. Corona frame buffer and c. management from Max.

11

[Max] Corona Goodies - User Contributions / Re: Alternative OCIO config for 3dsMax. ACES 2.0 and a few other view transforms.

« on: 2025-03-15, 09:12:02 »

point 3ds max to this ocio config, set it up according to your needs.

that is all I am able to offer as a tutorial.

12

[Max] I need help! / Re: Color accuracy

« on: 2025-03-14, 18:52:06 »

start with some theory: Pointer's gamut - real surface colours, measured.
https://tftcentral.co.uk/articles/pointers_gamut

Corona can process only the ones in the triangle (attached):

Could you please explain what exactly you mean here, and where you got that information from? Corona can, and does, "process" in wider gamut. In newest versions it's ACEScg (when using the 3ds Max OCIO mode). In older versions and when using the gamma 2.2 workflow, it used to be Adobe Wide RGB (for many, many, years). You can find the setting for this in "development/experimental stuff".
Max - https://support.chaos.com/hc/en-us/articles/4528523195537

C4D - https://support.chaos.com/hc/en-us/articles/4528469959953

I was rather referring to ability to input and output acescg colour information to and from Corona. Not long ago it was still restricted to lin rec709. Everything seems to be working as expected now.

my mistake. apologies. well done Corona.

I might be wrong again but this passed quite unnoticed, right? considering the amount of "Corona needs aces" whining back in a day.

13

[Max] I need help! / Re: Color accuracy

« on: 2025-03-14, 11:19:44 »

start with some theory: Pointer's gamut - real surface colours, measured.
https://tftcentral.co.uk/articles/pointers_gamut

Corona can process only the ones in the triangle (attached):

edit: no longer true. Corona is now capable of acescg inputs and outputs.

14

[Max] General Discussion / Re: Cryptomatte + Nuke, what's the ideal workflow?

« on: 2025-03-07, 17:51:27 »

so rendering twice is easier for you than a precomp in Nuke?

15

[Max] General Discussion / Re: Cryptomatte + Nuke, what's the ideal workflow?

« on: 2025-03-07, 17:09:55 »

no clue about Corona with Renderstacks/Deadline but CXR is multi layer by default and never multi part.
Nuke can do all the tonemapping available in Corona and more. it can also do everything you need with exr files - most likely convert multi layered to multi part - better performance in Nuke.