Yes, your first paragraph is good.
-on channel dependence,
in the film system, layers of the color response are coupled to each other. As you change green exposure, the red also changes. These are generally coupled together in descriptions of the “interlayer effect” which includes both different channels responding to a single color and the inhibitors present in film to reduce this effect.
Independent channels can change just Red and only the Red changes. The matrix was supplied by Kodak and Fuji as an average that would work across all films. If you know how a film was constructed, you can make a better matrix, but that is not for mere mortals.
– In general, 1D Luts are needed to change the behavior and conversion of the toe in converting into linear. (or vice versa) It can also be though of as ‘unbuilding’ the tone.
- on the EXP_TO_ACES matrix, no this was a different process for the film system, and we had a lot of help
from Kodak and Fuji color scientists.
Yes, it can be used as a grading space. But it works better when you have a film emulation LUT as the viewing LUT. In essence, ADX becomes the ‘negative’. You can always grade direct to a final output, but you may feel that the controls do not get you to where you want to go. The color conversion issues happen because you are trying to represent what was on a film that was scanned, and that does not easily go back to scene referred. Our conversion is a best effort at an average, but coming from film, certain colors are limited, we can’t reproduce the subtractive colors on film, and there is coupling between the colors that remains in a film scan that we have not removed. There can all be overridden by a colorist, but sometimes it is a chore.
There is never an inappropriate question