Feature request: increased LUT3D flexibility

[kmilos]

This is coming out of discussion in https://github.com/darktable-org/darktable/issues/10709 and https://github.com/darktable-org/darktable/pull/12260

The improved LUT3D module should:

• not assume input LUT profile = output LUT profile (i.e. separate the single LUT "application" profile to an input one and and output one); there are numerous LUTs that transfer from a wide gamut, log encoded space to a narrower/display one using some creative style...
• support input & output LUT profiles from ICC files (from user or system supplied color/in and/or color/out) and also use the existing built-in (working?) profile list, potentially deprecating the currently fixed and limited list (i.e. behave similar to working profiles list of the colorin module)
• optionally expose intent control for the working->lut_input and lut_output->working profile transforms

[aurelienpierre]

not assume input LUT profile = output LUT profile (i.e. separate the single LUT "application" profile to an input one and and output one); there are numerous LUTs that transfer from a wide gamut, log encoded space to a narrower/display one using some creative style...

That makes no sense. Or, by "profile", you actually mean "color space" ? In any case, having LUTs do the color space conversion removes any color traceability and voids the guaranty. Moreover, those log-encoded RGB belong only to cinema.

support input & output LUT profiles from ICC files (from user or system supplied color/in and/or color/out) and also use the existing built-in (working?) profile list, potentially deprecating the currently fixed and limited list (i.e. behave similar to working profiles list of the colorin module)

What problem is that supposed to solve ? Supporting stuff for the sake of supporting stuff is nonsensical, especially since ICC profiles are already supported where they should.

This FR sounds like someone woke up with grand ideas regarding features but no actual use case.

[phweyland]

LUT3D could be used for other use cases than color grading. There is some room between raw data and colorin which fits with the limit [0,1] domain and would require to have different input and output color spaces. For lack of LOG raw image I've never checked this case.

[github-actions[bot]]

This issue did not get any activity in the past 60 days and will be closed in 365 days if no update occurs. Please check if the master branch has fixed it and report again or close the issue.

[parafin]

I hit this limitation just now, specifically I want to use a LUT with ProPhoto linear RGB input and output colorspace and it is missing from the list. Could we at least extend the list with all built-in colorspaces we have? ProPhoto linear RGB is available in colorin iop as a working profile.

[kmilos]

@parafin I wasn't really planning on working more on https://github.com/darktable-org/darktable/pull/12265, so please feel free to take it over.

[parafin]

If there's noone working on this, I might add ProPhoto to the list, but I doubt I'll have enough motivation to tackle other points.

[github-actions[bot]]

This issue has been marked as stale due to inactivity for the last 60 days. It will be automatically closed in 300 days if no update occurs. Please check if the master branch has fixed it and report again or close the issue.