ACES feature requests

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@Willian_Aleman. So the 709 LUts are meant to be applied to a normalize 709 signal coming for any camera?

Nick, thanks a lot for your generosity. I won’t mind to pay or contribute for the labor of this type of work.

I haven’t experimented with the LUTs yet. I would prefer if Nick response to the question.

The LUTs I have posted are not to be applied to 709 signals. They create 709 signals with RRT/ODT applied from ACESproxy, ACEScc, ACEScct and LogC.

There are actually a number of LUTs available as part of the OCIO config:

I’m not sure I follow… What are these luts expecting as source color space?

The first part of each LUT’s name indicates the input colour space in expects. e.g. ACEScct_Rec709ODT_EE.cube expects the source to be ACEScct.

They all transform the input to ACES linear, then apply the RRT followed by the Rec.709 ODT.

The EE or LL part of the file name follows the ARRI LUT generator convention for input and output range.


I have a couple of suggestions or requests, but first a bit of context.

I was reading some code from aces-dev since i got a cheap deal on a Eizo monitor with HDR upgrade, but it peaks at 350nits, with the hardware modification being provided for PQ1000, PQ300, and HLG. The white level is well below the 1000nits specified in ST2048 and ARIB STD-D67/HLG (in ITU-R BT.2100 )

I was then trying to extend the ACES 1.0.3 configuration by adding an ODT for ST2084 with a white level of 300 nits, and noticed the ODT white levels are defined in ACESlib.Tonescales.ctl.
I’m not sure how to proceed from here since i cannot find information on how to arrive at the coefficients specified for the SegmentSplineParameters c9 ODT_1000nits, 2000nits, 4000nits, so that i could try to create one for what would be an ODT_300nits.

Also, presently there is no HLG ODT available. Is there a general preference in the industry for ST2084 over HLG?

I know some of these issues are planned for a future ACES release though, but it would be great to have the ability to have a somewhat user friendly way to edit the tonescales curves in order to allow one to create ODTs for ST2084, HLG with white levels other than the minimum set of 1000nits.
Perhaps alternatively, some kind of parametric ODT that would allow one to specify the white level in the respective CTL file, instead of having a family of ODTs for 1000nits, 2000nits, 4000nits for instance?

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