AgX in Corona

[zhao liang]

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/index.php?topic=41947.msg223544#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]

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]

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]

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]

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]

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

[mienda]

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" (

)  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.

[mienda]

 
Thank you very much for your answer Piotrus. This clarifies these tone mapping things that are still confusing for me

[piotrus3333]

Another example of using AgX:
Resolve AgX version (DCTL) married to look from famous ARRI K1S1 lut.