Post processing (contrast, gamma, luts) OCIO configs in LV

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Post processing (contrast, gamma, luts) OCIO configs in LV

Postby mohari.mate » Fri Jul 02, 2021 4:08 am

mohari.mate Fri Jul 02, 2021 4:08 am
Hi guys, when i load aces ocio 1.2 config and switch to ocio in LV, is there any chance to increase the contrast of the image ? LUTS, gamma, etc doesnt work, only exposure and saturation. Is there any way to postprocess the image ? It would be fantastic. Cuz sometimes it looks flat and dull.

Thanks, Lev
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby elsksa » Tue Jul 27, 2021 4:55 pm

elsksa Tue Jul 27, 2021 4:55 pm
Hi Lev, it is not possible due to the simple fact that when using OCIO, any non-OCIO color-operations/image manipulation would not be part of the OCIO based pipeline. OCIO is, in short, a color management framework, meant to be cross-application and to maintain consistency in a project. You can find some information in the following link: https://www.elsksa.me/scientia/cgi-offline-rendering/octane-render-color-management

It will work if you enable "Force Tone-mapping" but you will break the entire imagery doing so, it should never been applied/enabled.

Last but not least, It is possible that ACES is not appropriate for you, ACES has not been designed for everything nor everyone. If you want to play with "contrast-looks" on your imagery, I recommend Filmic OCIO By Troy.S - you can find more information here: https://www.elsksa.me/scientia/cgi-offl ... rvival-kit with direct-download-link in it.


PS: The default ACES "look" should not look flat. In Digital Imagery, Flat is usually referring to a logarithmic encoding, which looks "flat" on purpose. The display-referred result from ACES is rather "saturated and contrasted"
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby sdimaging » Fri Sep 10, 2021 2:55 am

sdimaging Fri Sep 10, 2021 2:55 am
ELSKSA:

I understand what you're saying, BUT I can still go into a custom AOV group, and tweak to my hearts desire because it's a POST addition - so in short, an ADDITIONAL LUT channel inside the POST EFFECTS tab would yield additional POST control that is external to all of the OCIO response - correct? That's where I would suggest an additional LUT channel be where custom LUTs can easily be generated from photoshop and applied as a post effect. The same way you would from opening to composite after the fact, just inside octane. Inside the imager would infact be a more non destructive approach - but simply put, you want to open up all shadows, adjust color, anything you'd also see from the magic bullet options, you should still be able to do regardless of the OCIO config with ACES and it just saves with an ACES-sRGB output jpeg/png?
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby elsksa » Fri Sep 10, 2021 6:37 am

elsksa Fri Sep 10, 2021 6:37 am
sdimaging wrote:ELSKSA:

I understand what you're saying, BUT I can still go into a custom AOV group, and tweak to my hearts desire because it's a POST addition - so in short, an ADDITIONAL LUT channel inside the POST EFFECTS tab would yield additional POST control that is external to all of the OCIO response - correct? That's where I would suggest an additional LUT channel be where custom LUTs can easily be generated from photoshop and applied as a post effect. The same way you would from opening to composite after the fact, just inside octane. Inside the imager would infact be a more non destructive approach - but simply put, you want to open up all shadows, adjust color, anything you'd also see from the magic bullet options, you should still be able to do regardless of the OCIO config with ACES and it just saves with an ACES-sRGB output jpeg/png?


Hi sdimaging,

I am strongly believing that you did not understood my previous message. I will do my best at simply explaining why your request is not viable:

Octane:
• Octane (at the moment) does not have "color corrections" tools as available in e.g V-Ray or Corona (the renderer) VFB https://docs.chaosgroup.com/display/VMAX/Color+Corrections. It might come to Octane in the future and must have been probably requested already.
• Using OCIO Filmic (from Troy Sobotka) provides various "contrast-looks" - I have attached a .gif (I do not know if it will preview on the forum).
octane_ocio_look_filmic_elsksa.gif


OCIO:
• OpenColorIO (OCIO) was initially developed (since 2003), open-sourced by Sony Pictures Imageworks and ❝ is an Academy Scientific and Technical Award winning color management solution for creating and displaying consistent images across multiple content creation applications during visual effects and animation production ❞ https://www.elsksa.me/scientia/cgi-offline-rendering/ocio.
• To simplify the understanding, one could think of OCIO as a "plug-in" that "takes over the native built-in color management options" of a given software (including renderers). Again, the wording is technically not appropriate but for the sake of simple explanations...
• What you are describing is already possible but requires the know-how when using OCIO.
• It is possible to use LUTs with OCIO, but it has to be set-up within the OCIO "environment/ecosystem". In order to do so, an understanding of the fundamentals will be necessary https://www.elsksa.me/scientia/cgi-offline-rendering/cgi-color-management-survival-kit - then, the OCIO documentation would contain information for using custom look-up-tables within an OCIO based color managed pipeline: https://opencolorio.readthedocs.io/en/latest/index.html however, understanding 1D and 3D look up tables is upmost important.

Unfortunately, Photoshop being far from a professional digital imaging software, the options are limited with it. In such case, and without relying on unofficially supported third-party plug-ins, the solution in your case would likely be to avoid using OCIO packages.

I hope it did clarify some of the questions or confusions you may have had. Please, do not hesitate to let me know if part of it was unclear.
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby sdimaging » Fri Dec 17, 2021 2:48 pm

sdimaging Fri Dec 17, 2021 2:48 pm
Just getting back to this, I completely get what you're saying I'm not talking about adjusting anything in OCIO or to the raw render data, as a POST step and process just like using a custom light AOV and setting it to soft light with a red hue... that effects the color and values post ACES OCIO, my point is a LUT or Gamma tab at the top of the hierarchy for the AOVGs does that not make sense. I can add a custom render layer mask with a value to adjust the black or white output, color, etc all in AOVGs with some layering. You're suggesting adding a few additional post elements isn't an option it's already rendered and these are post processes that effect pixels with already assigned output color transform from the OCIO. The AOV groups do not in anyway effect the render or image itself but are passes composited together the same way you'd utilize them elsewhere. Having a Curve or Levels histogram or LUT input atop of the stack is all im suggesting for additional flexibility.
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby elsksa » Sat Dec 18, 2021 12:23 pm

elsksa Sat Dec 18, 2021 12:23 pm
Hello sdimaging,
sdimaging wrote:You're suggesting adding a few additional post elements isn't an option it's already rendered and these are post processes that effect pixels with already assigned output color transform from the OCIO.

Being an option or not is up to the developers. It is technically possible but not currently available.
sdimaging wrote:The AOV groups do not in anyway effect the render or image itself but are passes composited together the same way you'd utilize them elsewhere. Having a Curve or Levels histogram or LUT input atop of the stack is all im suggesting for additional flexibility.

You are misunderstanding how the OCIO color management framework works and why it can not be randomly paired with "external" color operation/processing.

I would suggest to consult the some OCIO content and the official OCIO documentation:
https://www.elsksa.me/scientia/cgi-offline-rendering/ocio for an overall introduction (incomplete, work in progress)
https://opencolorio.readthedocs.io/en/latest/concepts/overview/overview.html for an overview
More pages are available, for further reading, at opencolorio.readthedocs.io.

Briefly, OCIO allows for "show look", referred as LMT in an ACES specific color pipeline. It requires the knowledge to properly generate the LUT(s) in question and to "implement it" in the OCIO configuration file, which can be easily edited.
https://opencolorio.readthedocs.io/en/latest/configurations/_index.html#configurations

To implement user-configurable control, the Camera Imager would have to be reworked to fit an OCIO based color pipeline within Octane itself. Similarly to how it is done in a post-application, but simplified in Octane since Octane is primarly a renderer and will likely not offer all the numerous color operators/processors options and features of a compositing or digital intermediate/color-grading-mastering software.
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby SSmolak » Sat Dec 18, 2021 7:38 pm

SSmolak Sat Dec 18, 2021 7:38 pm
elsksa wrote:
sdimaging wrote:ELSKSA:

• Using OCIO Filmic (from Troy Sobotka) provides various "contrast-looks" - I have attached a .gif (I do not know if it will preview on the forum).
octane_ocio_look_filmic_elsksa.gif



As I said before, at the moment using any of custom OCIO profiles like this generate only 8-bit output so this completly ruin any further software montage or post processing. Just like using standard Octane camera post processing.
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby elsksa » Sat Dec 18, 2021 9:02 pm

elsksa Sat Dec 18, 2021 9:02 pm
SSmolak wrote:As I said before, at the moment using any of custom OCIO profiles like this generate only 8-bit output so this completly ruin any further software montage or post processing. Just like using standard Octane camera post processing.

Not necessarily. This is entirely export-settings dependent.

Briefly, here is an overview:
• OpenEXR
1. Will be exported as "scene-referred" Linear-sRGB in 16-bit floating point (for beauty, 32-bit is overkill).
2. Therefore, OCIO will not have an impact to it, that is, for "Filmic OCIO" that some call "Filmic Blender". When using ACES based color pipeline, the exported OpenEXR file will encode to Linear-ACEScg (or Linear-ACES 2065-1, AP0).
3. The point of OCIO is to preview through an appropriate display rendering transform and re-apply the same process in post to have a match. This helps in lighting and shading, since without it, the standard sRGB encoding will result in many digital unwanted and mathematically wrong artifacts (clipping, skewing, volume errors, posterization and more).

• TIFF would be either 16-bit or 32-bit integer. If using Filmic OCIO, it is recommended to bake the Filmic Log Base Encoding to it, and apply the "contrast looks" from the OCIO package, in the software used for post.
This is the recommended workflow for software that are poorly "color managed" with a lack of 32-bit floating point engine and OpenEXR native support.

• PNG is not recommended for both rendering-output or web-ready-export. JPG would only be recommended for web-ready-export.
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby SSmolak » Sat Dec 18, 2021 11:49 pm

SSmolak Sat Dec 18, 2021 11:49 pm
Unfortunaterly whetever export settings and file type are used it has always only 8 bit depth if custom OCIO settings are used like Filmic Blender or even ACES Rec ones. I will try Octane Standalone maybe this is Cinema 4D issue.
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Re: Post processing (contrast, gamma, luts) OCIO configs in LV

Postby mohari.mate » Thu Jan 27, 2022 6:50 am

mohari.mate Thu Jan 27, 2022 6:50 am
Hi guys, is there anything happening with this thing ? At a curve adjustment lay or at least a lut support would be great for ocio LV look, finetuning the image before rendering is a huge plus, which is available in linear colorspace but not with ocio.

thanks, Lev
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