AgX in Corona

[Bowcat]

It’s great. Like the guy in the video said, it gives you something to work with. Definitely needs contrast and saturation, but as a starting point is very good.

Excellent video this one:

@burnin

^^Yes… more on & in-depth.

https://www.youtube.com/watch?v=YsTQEzcmD5w

[muoto_1]

actually, the trick of the two luts, one for the color matrix (especially for controling the “above 1” color values), one for the curve is pretty interesting.

i made a few of my own for the matrix and for the 1dlut curve, maybe less scientifically correct as the one of piotrus, but the results are nice !

thanks for the tip !

[piotrus3333]

@muoto

actually, the trick of the two luts, one for the color matrix (especially for controling the “above 1” color values), one for the curve is pretty interesting.

i made a few of my own for the matrix and for the 1dlut curve, maybe less scientifically correct as the one of piotrus, but the results are nice !

thanks for the tip !

unfortunately it’s impossible to be really precise with luts in Corona:
[https://forum.corona-renderer.com/ CIE - option to apply LUT without hidden gamma transforms. ](https://forum.corona-renderer.com/ CIE - option to apply LUT without hidden gamma transforms. )

• you can (probably, I have not tried) improve my matrix lut by creating one that will cover 0 - 16.something float range
• 1dlut as the second lut is the right way to go (in that case look lut can be the third one, again - probably - would be still precise enough)

edit: in general, considering ACES OT not being updated with important aces fixes from 2021, and post being done in CIE, AgX is great option for Corona users.

[liang_zhao]

Hello, do you need to add OCIO configuration environment variables in the corona renderer?

[maru]

@zhao liang

Hello, do you need to add OCIO configuration environment variables in the corona renderer?

Hi, sorry, but I am not sure what exactly you mean, and also there is no need to report your own posts to moderators.
Can you please explain what kind of help or answer you are seeking?

[liang_zhao]

Hello, I need the moderator’s answer because in addition to adding lut, do I need to load the ocio environment variable of AGX when setting up AGX?

[maru]

Please note that you should only report posts if you need some help from forum moderators - for example if you posted your forum thread in a wrong forum section or if you would like to report spam.

Regarding the environment variable option - it is currently not supported. If you set Corona as your renderer and select the “OCIO - Environment Variable” you will see an error message from Corona.
See: https://support.chaos.com/hc/en-us/articles/20283060170257

[piotrus3333]

@zhao liang

Hello, do you need to add OCIO configuration environment variables in the corona renderer?

no, just luts.
created with legacy gamma setup in 3dsMax 2024 in mind.

[liang_zhao]

Thank you for your answers! Is it useful to add ocio Vray renderer to environment variables?

[piotrus3333]

@zhao liang

Thank you for your answers! Is it useful to add ocio Vray renderer to environment variables?

VRAY_VFB_OCIO - no.
OCIO - yes, if you are using only/mostly one ocio config.

[liang_zhao]

Thank you for your answers!

[piotrus3333]

More of AgX by Troy Sobotka - this time his Resolve version of it (quite different) married with a film look from Arri:
https://forum.corona-renderer.com/ Improved support of max colour management #msg223544

note: it does require a string option to turn off VFB’s sRGB view lut so might be a bit more cumbersome to use.

[muoto_1]

But when importing exr’s from corona to fusion, there is a extra gamma applied (1.2?) because the image in fusion is much darker than in VFB. And then you need to specify the float gamma thing to have the same result in vfb and fusion ?

[piotrus3333]

@muoto

But when importing exr’s from corona to fusion, there is a extra gamma applied (1.2?) because the image in fusion is much darker than in VFB. And then you need to specify the float gamma thing to have the same result in vfb and fusion ?

AgX luts for Corona from this thread are made for default Corona behaviour regarding gamma transforms in VFB. by default VFB has hidden 2.2 transform after the TONE MAPPING stack and effects. it also has hidden gamma transforms in every LUT operator.
if you are using my AgX luts there is no need for string option changing VFB’s gamma behaviour (“float gamma thing”).

[pokoy_1]

@piotrus3333

@muoto

But when importing exr’s from corona to fusion, there is a extra gamma applied (1.2?) because the image in fusion is much darker than in VFB. And then you need to specify the float gamma thing to have the same result in vfb and fusion ?

AgX luts for Corona from this thread are made for default Corona behaviour regarding gamma transforms in VFB. by default VFB has hidden 2.2 transform after the TONE MAPPING stack and effects. it also has hidden gamma transforms in every LUT operator.
if you are using my AgX luts there is no need for string option changing VFB’s gamma behaviour (“float gamma thing”).

Wait, so for any LUTs from outside Corona install we need either the string option or a gamma operator @0.45 before the LUT? I remember trying some LUTs from other sources but gave up thinking they were not the right type.

[piotrus3333]

@pokoy

Wait, so for any LUTs from outside Corona install we need either the string option or a gamma operator @0.45 before the LUT? I remember trying some LUTs from other sources but gave up thinking they were not the right type.

I do not know the story behind luts from Corona installer but, in general - yes - to have a lut do what it is supposed to do in Corona VFB you need gamma transform operator (1/2.2).
I guess the story why it all works like that is long forgotten as the support was unable to point me to the simple solution - the string option for adjusting VFB gamma. I dug it out from an old 2015 post.

[piotrus3333]

ok, so at least we know that it used to work as expected for a brief moment:

[muoto_1]

would anyone have a nuke layout that would work creating LUT’s that would look similar in Nuke as in Corona Vfb ?

[lilou]

Hello, I just saw this video on YouTube which deals with a so-called new tone mapping for Blender “he Khronos PBR Neutral Tone Mapper” (https://www.youtube.com/watch?v=iQ3m0CfuSmg) which seems to have the advantages of AGX without its disadvantages (lack of contrast and saturation depending on everyone’s tastes). I have the impression that the combo of AGX MATRIX + AGX PUNCHY (+ contrast if necessary) is close compared to the combination AGX BASE + AGX KRAKEN + AGX DEFAULT CONTRAST.
I’m really uneducated about these issues so I was wondering what you thought about it.

Thanks in advance

[piotrus3333]

AgX in the form of luts from this thread is not the same AgX you have in Blender. There are three different versions of AgX - the one I uploaded is based on the original idea from Sobotka. it does not shift hues like the Blender 4 version. it is also made with BT709 primaries (what you would colloquially call srgb primaries) in mind.

agx matrix + punchy is, well, more punchy than agx matrix + kraken + default contrast. default contrast is called base look in original AgX ocio configuration. you can replace default contrast lut with your own curve or add colour grading lut on top of Kraken. punchy look if I remember correctly is just gamma adjustment - just a simple sample look, nothing to stick with. so this AgX basically will require your personal input in regards to final contrast.

it is possible than some other, preset based, display transform would be better suited for use in Corona: for example RED display transform consists of 16 combinations of 4 levels of contrast and 4 different highlight roll off strengths.

Khronos PBR Neutral Tone Mapper - I think they are trying to solve issues with colour reproduction for some quite specific cases. does any image in the video look natural to you? instead of rendering in wider gamut space and using some tried and tested colour science (from camera manufacturers for example) they are fiddling with display transform alone. BT709 colour space is too tiny to describe all real life colours - look at professional cameras: at least BT2020.
EDIT: ok, so this is indeed designed specifically for e-commerce. very different beast, very different needs. not for us.