ACES way to control how much the highlights gets compressed? Tweet

[MantasKava]

Hello,

The topic name sums it up pretty well I think. But just to be sure:
In Redshift there's this option called "Allowed overexposure"

That lets me control how much the highlights get suppressed.
Now the question is, how do I control this in Octane?

P.S. We're talking ACES workflow here

[elsksa]

Hi,
It goes against how ACES has been designed.

There are incorrect "post-process stack" implementations in Corona and possibly in RS too.
If the non-OCIO stack tools are affecting the output, when OCIO is enabled, then it is incorrect.
It will be prone to produce broken results.

I don't think that option in RS is related to ACES (or any OCIO package) at all.

Over-exposing is already possible and always has been. From the Camera Imager.
https://www.elsksa.me/scientia/cgi-offline-rendering/octane-render-color-management

Worth mentioning: Over-exposition ≠ clipping.

[MantasKava]

Wow, lots of valuable info on your website. Though I must admit it's a bit much for me to digest it all in one sitting.
I'm afraid we can quickly fall into this rabbit hole of color science, but I have many questions for a long time now, and you look like someone who could answer some of those to me. So let me ask:

1. Main reason (for me) for using/trying ACES is to get rid of constant clipping/overexposed/burned highlights, or not nice looking highlights in general (it's a problem when working with interiors, especially). There's an over-saturated highlights problem also. And ACES helps tremendously in this regard, no burned-out/clipped highlights anymore, I'd even say highlights get compressed too much. Which is another problem and that is the reason why I started this topic to begin with). Question- am I choosing the wrong solution for my problem?

2. If ACES is so "bad" for 99.9% of the users, why is such a major developer as Maxon/Redshift implementing it into their software as default? Hard to believe they are too stupid to know this stuff.

3. What file format/bit depth/color space should I use when exporting for PP in an external app (Fusion in this case) when using Filmic AgX or Filmic Blender?

4. Which one do I select here? If I want to export for PP in Fusion.


5. Is this the right OCIO View option when using Blender Filmic? Every other option looks really wrong I found.


6. What is this button for?

[MantasKava]

Just for clarification:


This is when NOT using ACES. How do I achieve this look without it? Pay attention to the highlights.

[elsksa]

(...) I must admit it's a bit much for me to digest it all in one sitting.

Indeed, it's quite overwhelming at first and "won't happen over night". Take your time. The reward is worth it.

1. Main reason (for me) for using/trying ACES is to get rid of constant clipping/overexposed/burned highlights, or not nice looking highlights in general (it's a problem when working with interiors, especially).

Filmic AgX does the same, in a much simpler way, with minimized visual flaws, as opposed to ACES.

There's an over-saturated highlights problem also. And ACES helps tremendously in this regard, no burned-out/clipped highlights anymore.

Aside from the highlight roll-off, ACES has hideous color-skewing (e.g. red will skew to orange, blue to cyan, etc), always visible on intense light sources and any surface reflections, including highlights.

I'd even say highlights get compressed too much. Which is another problem and that is the reason why I started this topic to begin with).

That's by design (Reference Rendering Transform aka RRT, which outputs is called "OCES") from where the "filmic aesthetic" comes from (in reference to the celluloid film medium) and has been a topic of discussion reported to them (a long debate). The end-user can't do anything about that. The subjective ACES look is also not appreciated by everyone.

Question- am I choosing the wrong solution for my problem?

This answer has been spoiled.

2. If ACES is so "bad" for 99.9% of the users, why is such a major developer as Maxon/Redshift implementing it into their software as default? Hard to believe they are too stupid to know this stuff.

❝Just because everyone is doing it, doesn't mean it's right. And just because no one is doing it, doesn't mean it's wrong.❞

Digital Imaging is an entirely different domain with its own research & development fields, scientists, etc.
It's not what developers specialize on, nor majority of end-users. Awareness is highly important.
Octane just output light data. It can then be managed in various ways, with OCIO or without, which would imply a higher level of knowledge and skills from a digital imaging technician/colorist. Filmic AgX is the only reliable solution out here, for those that do not specialize in advanced post-production.

3. What file format/bit depth/color space should I use when exporting for PP in an external app (Fusion in this case) when using Filmic AgX or Filmic Blender?

The gold standard and primary choice is always:
OpenEXR, 16-bit (for beauty, and 32-bit for data AOVs).
The "compression type" depends on various factors, the choice is yours. Otherwise, TIFF.
Some more information.

4. Which one do I select here? If I want to export for PP in Fusion.

If you plan to replace ACES with Filmic OCIO AgX, any ACES option is completely irrelevant (as there are some native ACES options in Octane).
Looks like it's AgX loaded, it would be: Linear BT.709 (the exact same as Linear-sRGB).
I'm not familiar with Cinema 4D GUI, it's not 1:1 matching Standalone since it's part of a 3D DCC.
On Standalone, default settings are correct. I don't know how is this handled in Octane Cinema 4D.
I will update my Octane pages with that AgX setup information.

5. Is this the right OCIO View option when using Blender Filmic? Every other option looks really wrong I found.

Looks like this one is the original ("legacy") Filmic OCIO.
I would recommend to stick with AgX as it is a drastically improved version.
To answer:
• The first one is the Log-Encoding, similarly to the log encoding from digital cinema cameras.
• The second one is the conforming from Log-encoded (OETF) to display (EOTF).
The original Filmic OCIO package offers various "contrast intensities", which go from "base contrast" up to "high contrast", and everything in between (in addition to two bonus options: black-and-white & false color).

6. What is this button for?

It's to apply the "ACES Look" using the official ACES implementation, without the need of OCIO.
It's explained here, and also why it's a limited option (no post possible when using it).

[MantasKava]

Looks like this one is the original ("legacy") Filmic OCIO.
I would recommend to stick with AgX as it is a drastically improved version.

Do I understand correctly, that by "legacy" you mean Blender-Filmic one? that you mentioned in your blog as well.
And so AgX is newer/updated version of Blender-Filmic, correct?

[MantasKava]

And just to confirm- I load up AgX OCIO, set the Camera Imager Ocio view to "sRGB:Appearance Punchy" and that's it, I am good to go? If I want to ditch ACES and try out this AgX thing that is

[elsksa]

Do I understand correctly, that by "legacy" you mean Blender-Filmic one? that you mentioned in your blog as well. And so AgX is newer/updated version of Blender-Filmic, correct?

Correct. It was originally called Filmic Blender, I prefer to refer to it as Filmic OCIO and mention if it's the legacy (original "Blender" one) or newer AgX.

And just to confirm- I load up AgX OCIO, set the Camera Imager Ocio view to "sRGB:Appearance Punchy" and that's it, I am good to go? If I want to ditch ACES and try out this AgX thing that is

Correct. As mentioned, it's a simpler and straight-forward solution.
For Fusion, the version 18 is needed as AgX is OCIO 2 compliant.
The steps are as follow: an EXR 16-bit beauty (linear) export, plugged to an OCIO node in Fusion with AgX loaded and set to Input source: Linea BT.709 and Output source to sRGB:Appearance Punchy.

[SSmolak]

In my opinion ACES can completely ruin most of the exterior scenes with strong sunlight. Shadows and shadow areas are too dark. Reflection in windows are too much saturated and they have color hue issues. These issues can't be repaired even in post.

[elsksa]

These issues can't be repaired even in post.

They absolutely can. They just shouldn't be here in the first place.

To clarify: the issues are at the core, any "fix" is considered a workaround, the core issues will remain.