Add "smart" OCIO settings for different image / movie inputs

[SteffenDuenner]

Right now, when viewing 8bit PNGs or JPGs with sRGB content I have to either manually switch off OCIO or set the input and display color space to sRGB. When afterwards viewing a 16bit half-float EXR I have to make sure that OCIO is active and set it to linear input / sRGB display. Depending on the stuff I need to view I have to change OCIO settings all the time.

Somehow it would be nice if DJV offered some way to set defaults for different bit depth inputs, so that e.g. 8 or 16bit integer inputs would be treated as sRGB while 16 or 32bit float inputs as being linear.
Additionally it would help if the same also goes for the View and Look settings so that DJV automagically shows integer (LDR) inputs with a standard sRGB (or Rec.709 or P3 or whatever the user prefers) while showing linear float inputs (HDR) with a different View and Look setting to allow tone-mapping, gamut-compression and the likes.

And while we're at it: OpenEXR 3.4.0 now has a "colorInteropID attribute" ( https://openexr.com/en/latest/news.html#id1:~:text=%E2%9C%A8%20New%20%60colorInteropID,of%20OpenEXR%20Files ) that gives a clue about the used color space (linear AP0, AP1, Rec.709, ...) and can be used to set DJV's input color space accordingly, so that e.g. linear ACEScg AP1 or linear Rec.709 inputs are automatically treated as such.

[darbyjohnston]

Thanks for the suggestions, I agree that changing settings all the time is a pain. As a compromise to having the OCIO's changed automatically, would having keyboard shortcuts to select different profiles be reasonable?

Also do you use any integer files that are not sRGB, like Cineon or DPX?

[SteffenDuenner]

Having keyboard shortcuts to switch between profiles sounds intriguing. In the end it's just very few profiles in my daily work:

• sRGB in - sRGB out (basically switch off OCIO and just display the pixel values of the source file)
• linear Rec.709 in - tonemapped AgX sRGB out
• linear Rec.709 in - tonemapped ACES 2.0 sRGB out
• linear ACEScg in - tonemapped AgX sRGB out
• linear ACEScg in - tonemapped ACES 2.0 sRGB out
  the last 4 in combination with a "Look" like "High Contrast" or "Reference Gamut Compression"... and sometimes linear -> False Color for debugging stuff.

So putting these on shortcuts or preset buttons in the toolbar would be awesome I guess.

And while thinking about it, I noticed that it must be many years already that I last had to deal with dpx or even cin files.

[darbyjohnston]

Thanks, that list of profiles is helpful. Is the file type enough to determine which of those to use?

That's interesting about the DPX and Cineon files, they are handy formats but I have wondered how much use they get these days.

[SteffenDuenner]

In the end Cineon files are hard-coded to 10bit IIRC and dpx can be anything between 8- and 16bit. Additionally while both formats usually contain log-colors it's not saved anywhere in a header. So it can basically be any log-format imaginable and will need manual tweaking anyways.

[darbyjohnston]

I've been looking into this some more and will try and add per-file OCIO settings in an upcoming release.

@SteffenDuenner Have you heard of the "file_rules" feature in OCIO config files?
https://opencolorio.readthedocs.io/en/latest/guides/authoring/rules.html#config-rules

[SteffenDuenner]

Hmm, actually I never heard of it before. Sounds intriguing but in the end I'm more of an OCIO end user ;)
I just use existing OCIO config and I don't know any that uses this feature AFAIK.