[DCP-o-matic] P3 Color Space

Hi Carl, I noticed there have been some recent changes/improvements to the color conversion, assisted by Dennis Couzin. I would like to pick up one issue that seems to have remained unsolved in some previous discussions, and where I have a hard time to understand the issue completely myself. That is, source footage in P3 color space. More and more people use Adobe products and especially DaVinci Resolve for editing/grading, and quite a few of them are encouraged to use P3 for their editing, because they are told this would be the recommended color space for DCI work. Hence I would like to assume that when creating a final master within that color space, that this is already in XYZ. But that doesn't seem to be the case? As more and more people are using RAW cameras with a wider gammut than plain sRGB or rec709, I think we should address this issue. There have been a few questions regarding proper P3 conversion on this list before, and I think they have been left unanswered. When I google for this, there seems to be quite a bit of confusion. I'm not even sure wether P3 in DaVinci Resolve could be only a preview colourspace that is used when suitable display devices are connected. Maybe Dennis can help in solving that puzzle as well? - Carsten