Thanks for the details Jim.
I understand your point on the ADX to ACES vs. ACES to ADX transforms, would it be correct to say that the former is close to an IDT an the latter would be a special case of ODT (not involving the RRT) ?
Trying to get a high level understanding of the ADX to ACES transform, several points are not obvious to me :
- What are exactly Channel Dependent vs. Channel Independent densities and how the matrix was derived ?
- Why is an 1D LUT necessary to model the conversion from density to log-exposure for the low end part of the density range ?
- Finally, was the EXP_TO_ACES matrix derived in a way similar to what is described in the procedure for IDT design (P-2013-001) ?
Other uses of ADX might be possible, but it important to remember that the film side chain has a lot of particulars that make back and forth between ACES and ADX and then ACES have some color conversion issues.
I have seen it used as a grading colorspace pretty often, if you have any comment or more details on the possible color conversions issues involved I would be interested.
I hope these are not inappropriate or wrong questions.