Artifacts in ODT shadows mapping

[meleshkevich (Anton Meleshkevich)]

@jedsmith

Just coming back to say that this particular example is being caused by the cyan on the helicopter being out of the BT.709 gamut.

Thank you!
But seems like even if I soft clip that, ODT introduces it again.

1. AP1 ACEScct converted to Rec709 primaries and Rec709 OETF. W Point nodes are for converting white point, because Resolve doesn’t do it automatically. And in the end I added gamma operation to make everything brighter. Grayed out darker nodes are bypassed.
   We can see the out-of-gamut clipping. Triangle on the analyzer is for rec709 gamut.
   

   

2. I soft clip out-of-gamut colors back to Rec709 gamut. Artifacts are disappeared.
   

   

3. Rec709 primaries and Rec709 OETF image goes back to AP1 ACEScct. And then to ACES Rec709 ODT. The artifacts are here again.
   

   
   
   (Also you can notice clipped higlights. This is because of how soft clip in Resolve works. So the highlights are clipped at 100 nit in rec709 OETF)

I used CAT02 for white point conversion. Not sure if this is correct. But with Bradford artifacts are also there. So this probably isn’t the reason.