Here is a comparison of J between ACES 1.2 SDR output and the standard output from a CAM transform from Average to Dark viewing conditions. White whitepoint adjusted to match 0.18 grey.
As should be expected the ACES 1.2 (and all ACES output transforms to date) the values match very closely the ideal tonal scale for a Dark surround condition, plus the required roll off to fit values above 1.0 onto SDR displays, and maybe a little slope in shadow region to offset viewing flare.
This is probably no news to anyone who is has been involved in the development of ACES at any point.
The next post may start to get more interesting….