Do we need to change ACEScct

[tjdcs (Tucker Downs)]

@SeanCooper

While the conversation has focused on the ALEXA 35, it need not be, this ACEScct update (or lack thereof) will last for a long time so should be viewed on the ~10 year timescale if I base it on the current lifespan of ACEScct. I just view it as an opportunity for change and to anticipate needs over the next decade or so ( not that this is the last opportunity, but certainly a natural break ).

I definitely agree the principle problem area is on-set: with quantization, CDL behavior, exposure evaluation, and exposure latitude working against each other.

Yes, and my point earlier about quantization in on set grading is that there has been some neighing about 10-bit quantization fundamentally limiting how aggressive this update can be. If we desire a more aggressive curve with a much larger DR between 0 and 1 (or we define a separate quantization scheme for display-routed signals) then we should not focus on the limitations of 10 bit. They will be gone long before our idealized 10 year timeline.

However, (and I can’t remember who made this point in meetings but also @daniele here) there is some concern that a more aggressive, higher DR curve might start to lose functionality with CDL and legacy tools.

I think at this time we have a reasonable proposal from @jzp ACESlog Strawman Proposal

We should evaluate a more aggressive proposal without considering the limitations of 10-bit signals and then see a few tests of CDL and other tools to see how well they behave.

Lastly… There is a future issue that camera DR will continue to improve and improve and improve. So with that in mind… at some point limiting the log encoding for the purposes of preserving legacy tool “feel” sounds like it will become impossible. What will happen at that point?